485BPOS

As filed with the Securities and Exchange Commission on November 7, 2012

Securities Act Registration No. 2-34223

Investment Company Act File No. 811-1829

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Post-Effective Amendment No. 95

and

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940

Amendment No. 70

COLUMBIA ACORN TRUST

227 West Monroe Street, Suite 3000

Chicago, Illinois 60606

Telephone number: 312.634.9200

Charles P. McQuaid Columbia Acorn Trust 227 West Monroe Street, Suite 3000 Chicago, Illinois 60606	Scott R. Plummer c/o Columbia Management Investment Advisers, LLC 225 Franklin Street Boston, MA 02110	Mary C. Moynihan Perkins Coie LLP 700 13th Street, N.W., Suite 600 Washington, D.C. 20005
(Agents for service)

It is proposed that this filing will become effective:

¨ immediately upon filing pursuant to rule 485(b)

x on November 8, 2012 pursuant to rule 485(b)

¨ 60 days after filing pursuant to rule 485(a)(1)

¨ on                      pursuant to rule 485(a)(l)

¨ 75 days after filing pursuant to rule 485(a)(2)

¨ on                      pursuant to rule 485(a)(2).

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn Emerging Markets Fund^SM

Ticker Symbols

Class R4 Shares CAERX

Class R5 Shares CANRX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn Emerging Markets Fund	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	6
Performance Information	9
Investment Manager and Portfolio Manager(s)	10
Purchase and Sale of Fund Shares	10
Tax Information	10
Payments to Broker-Dealers and Other Financial Intermediaries	10
Additional Investment Strategies and Policies	11
Management of the Fund	14
Board of Trustees	14
Primary Service Providers	14
Other Roles and Relationships of Ameriprise Financial and its Affiliates – Certain Conflicts of Interest	17
Certain Legal Matters	18
Choosing a Share Class	19
The Funds	19
Summary of Share Class Features	19
Sales Charges and Commissions	22
Reductions/Waivers of Sales Charges	27
Distribution and Service Fees	29
Selling Agent Compensation	30
Buying, Selling and Exchanging Shares	32
Share Price Determination	32
Transaction Rules and Policies	33
Buying Shares	38
Selling Shares	43
Exchanging Shares	44
Distributions and Taxes	47

Columbia^SM, Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

	Investment Objective
	Fees and Expenses of the Fund
	Principal Investment Strategies
	Principal Risks
	Performance Information
	Other Roles and Relationships of Ameriprise Financial and its Affiliates – Certain Conflicts of Interest

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Columbia Acorn Emerging Markets Fund

 Investment Objective

The Fund seeks long-term capital appreciation.

 Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class R5 Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class R5 Shares
Management fees		1.25	%		1.25	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%
Other expenses(a)		12.18	%		12.10	%
Total annual Fund operating expenses		13.43	%		13.35	%
Fee waivers and/or reimbursements(b)		-11.83	%		-11.89	%
Total annual Fund operating expenses after fee waivers and/or reimbursements		1.60	%		1.46	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

^(b)  Columbia Wanger Asset Management, LLC (the Investment Manager) has contractually agreed to waive fees and reimburse certain expenses of the Fund so that the ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rates of 1.60% and 1.46% of the Fund’s average daily net assets attributable to Class R4 and Class R5 shares, respectively, through November 8, 2013. The Investment Manager may recoup any fees waived and/or expenses reimbursed with respect to any share class of the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in this prospectus, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This expense arrangement may only be modified or amended with approval from all parties to such arrangements, including the Fund and the Investment Manager.

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Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4 or Class R5 shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire on November 8, 2013, they are only reflected in the 1 year example and the first year of the 3 year example.

Based on the assumptions listed above, your costs would be:

	1 year		3 years
Class R4 Shares	$	163	$	2,711
Class R5 Shares	$	149	$	2,687

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 9% of the average value of its portfolio.

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 Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowing for investment purposes) in companies located in emerging market countries, including frontier market countries. Emerging market countries are those countries whose economies are developing or emerging from underdevelopment (for example, China, India, Poland and Turkey). Frontier market countries generally have smaller economies and even less developed capital markets than traditional emerging market countries (for example, Vietnam, Colombia, Nigeria and Kazakhstan). For purposes of the Fund’s policies, the Fund may invest in a company if (i) it is domiciled in, or the principal trading market for its securities is in, an emerging market country, (ii) it derives 50% or more of its economic value from goods produced, sales made or services performed or has at least 50% of its assets in an emerging market country or countries or (iii) it is a holding company that predominantly holds shares in such companies. The Fund may invest in a variety of countries, industries and sectors and does not attempt to invest a specific percentage of its assets in any given country, industry or sector.

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of small- and mid-sized companies with market capitalizations under $5 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $5 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $5 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $5 billion. Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $5 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies.

The Fund takes advantage of the Investment Manager’s research and stock-picking capabilities to initially invest in a limited number of companies (generally under 100), offering the potential to provide above-average growth over time.

Generally, the Investment Manager will determine which countries are emerging market countries by reference to the countries included in the S&P Emerging Markets Broad Market Index (BMI), and will determine which countries are frontier market countries by reference to the countries included in the S&P Frontier BMI. In addition, the Fund may invest in certain developing market countries that are not included in either the S&P Emerging Markets BMI or the S&P Frontier BMI (for example, Serbia and Senegal), but which are included on another independent third-party listing of emerging market and/or frontier market countries. The Investment Manager will make all determinations as to whether a company is an emerging market company at the time of investment. The countries that comprise emerging market countries, including frontier market countries, may change from time to time.

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

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 Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

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• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

• Frontier Market Risk – Frontier market countries generally have smaller economies and even less developed capital markets than traditional emerging market countries and, as a result, the risks of investing in emerging market countries are magnified in frontier market countries. The magnification of risks are the result of: potential for extreme price volatility and illiquidity in frontier market countries; government ownership or control of parts of private sector and of certain companies; trade barriers, exchange controls, managed adjustments in relative currency values and other protectionist measures imposed or negotiated by the countries with which frontier market countries trade; and the relatively new and unsettled securities laws in many frontier market countries.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established

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companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

• Currency Risk – Securities denominated in non-U.S. dollar currencies are subject to the risk that, for example, if the value of a foreign currency were to decline against the U.S. dollar, such decline would reduce the U.S. dollar value of any securities held by the Fund denominated in that currency.

• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Special Situations Risk – Securities of companies that are involved in an initial public offering or a major corporate event, such as a business consolidation or restructuring, may present special risk because of the high degree of uncertainty that can be associated with such events. Securities issued in initial public offerings often are issued by companies that are in the early stages of development, have a history of little or no revenues and may operate at a loss following the offering. It is possible that there will be no active trading market for the securities after the offering, and that the market price of the securities may be subject to significant and unpredictable fluctuations. Investing in special situations may have a magnified effect on the performance of funds with small amounts of assets.

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 Performance Information

Because the Fund commenced investment operations on August 19, 2011, no year-by-year total return bar chart or average annual total return table is being presented. The year-by year-total return bar chart and the average annual total return table will be provided after the Fund has annual returns for at least one calendar year.

Recent performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

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Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Managers

Fritz Kaegi

Lead manager since inception in August 2011.

Stephen Kusmierczak, CFA

Lead manager since inception in August 2011.

P. Zachary Egan, CFA

Co-manager since inception in August 2011.

Louis J. Mendes, CFA

Co-manager since inception in August 2011.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

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Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once

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posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Transactions in Derivatives

Although the Fund may execute transactions in derivative instruments, such as hedging transactions in specific foreign currencies, it generally does not do so. The Fund may, however, engage in limited currency forward transactions designed broadly to align the currency exposure of the Fund with the country weightings reflected in the Fund’s primary benchmark.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact

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that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

The Fund may hold up to 20% of its assets in cash under normal circumstances. Because the Fund commenced operations on August 19, 2011 and has only been in operation for a short time, its portfolio is relatively small and significant cash inflows may temporarily cause the Fund to have an increased cash position as the Investment Manager works to invest cash holdings pursuant to the Fund’s principal investment strategies.

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Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 1.25% of average daily net assets of the Fund.

14

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual report to shareholders for the fiscal period ended June 30, 2012.

Portfolio Managers

Information about the Investment Manager’s portfolio managers who are primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about each portfolio manager’s compensation, other accounts managed by each portfolio manager and each portfolio manager’s ownership of securities in the Fund.

Fritz Kaegi

Lead manager since inception in August 2011.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 2004. Vice President of the Trust since 2011. Mr. Kaegi began his investment career in 1998 and earned a B.A. from Haverford College and an M.B.A. from the Stanford Graduate School of Business.

Stephen Kusmierczak, CFA

Lead manager since inception in August 2011.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 2001. Vice President of the Trust since 2011. Mr. Kusmierczak began his investment career in 1999 and earned a B.A. from Bowdoin College and an M.P.A. from Princeton University, Woodrow Wilson School of Public and International Affairs.

P. Zachary Egan, CFA

Co-manager since inception in August 2011.

Portfolio Manager and Director of International Research of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1999. Vice President of the Trust since 2003. Mr. Egan began his investment career in 1999 and earned a B.A. from Middlebury College and an M.A. from the University of Chicago.

Louis J. Mendes, CFA

Co-manager since inception in August 2011.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 2001. Vice President of the Trust since 2003. Mr. Mendes began his investment career in 1986 and earned a B.A. from Columbia University and an M.I.M. from the American Graduate School of International Management.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

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The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

Expense Reimbursement Arrangements

The Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that the ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rates of 1.60% and 1.46% of the Fund’s average daily net assets attributable to Class R4 and Class R5 shares, respectively, through November 8, 2013. The Investment Manager may recoup any fees waived and/or expenses reimbursed with respect to any share class of the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in this prospectus, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This expense arrangement may only be modified or amended with approval from all parties to such arrangements, including the Fund and the Investment Manager.

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 Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the  icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,^* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4 and Class R5 shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares- Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

22

qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a %  of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per  share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per  share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

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investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) — (Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

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Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

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For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

48

• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• If at the end of the taxable year more than 50% of the value of the Fund’s assets consists of securities of foreign corporations, and the Fund makes a special election, you will generally be required to include in income your share of the foreign taxes paid by the Fund. You may be able to either deduct this amount from your income or claim it as a foreign tax credit. There is no assurance that the Fund will make a special election for a taxable year, even if it is eligible to do so.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis,

49

holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund.

It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

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Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^© 2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1822-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn European Fund^SM

Ticker Symbol

Class R5 Shares CAEEX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn European Fund	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	5
Performance Information	8
Investment Manager and Portfolio Manager(s)	9
Purchase and Sale of Fund Shares	9
Tax Information	9
Payments to Broker-Dealers and Other Financial Intermediaries	9
Additional Investment Strategies and Policies	10
Management of the Fund	13
Board of Trustees	13
Primary Service Providers	13
Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest	16
Certain Legal Matters	17
Related Performance Information	18
Choosing a Share Class	19
The Funds	19
Summary of Share Class Features	19
Sales Charges and Commissions	22
Reductions/Waivers of Sales Charges	27
Distribution and Service Fees	29
Selling Agent Compensation	30
Buying, Selling and Exchanging Shares	32
Share Price Determination	32
Transaction Rules and Policies	33
Buying Shares	38
Selling Shares	43
Exchanging Shares	44
Distributions and Taxes	47

Columbia^SM, Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

	Investment Objective
	Fees and Expenses of the Fund
	Principal Investment Strategies
	Principal Risks
	Performance Information
	Other Roles and Relationships of Ameriprise Financial and its Affiliates - Certain Conflicts of Interest

2

Columbia Acorn European Fund

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R5 Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R5 Shares
Management fees		1.19	%
Distribution and/or service (Rule 12b-1) fees		0.00	%
Other expenses(a)		17.83	%
Total annual Fund operating expenses		19.02	%
Fee waivers and/or reimbursements(b)		-17.66	%
Total annual Fund operating expenses after fee waivers and/or reimbursements		1.36	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

^(b)  Columbia Wanger Asset Management, LLC (the Investment Manager) has contractually agreed to waive fees and reimburse certain expenses of the Fund so that the ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rate of 1.36% of the Fund’s average daily net assets attributable to Class R5 shares, through November 8, 2013. The Investment Manager may recoup any fees waived and/or expenses reimbursed with respect to any share class of the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in this prospectus, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This expense arrangement may only be modified or amended with approval from all parties to such arrangements, including the Fund and the Investment Manager.

3

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R5 shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire on November 8, 2013, they are only reflected in the 1 year example and the first year of the 3 year example.

Based on the assumptions listed above, your costs would be:

	1 year		3 years
Class R5 Shares	$	138	$	3,548

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 17% of the average value of its portfolio.

4

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowing for investment purposes) in European companies. Under normal circumstances, the Fund invests at least 70% of its total assets in companies in Western European countries (for example, the United Kingdom, Germany, France and Italy), but also may invest up to 30% of its total assets in companies in emerging Central and Eastern European countries (for example, Poland, the Czech Republic, Turkey and Cyprus), including up to 10% of its total assets in companies in Russia and the Ukraine. For purposes of the Fund’s policies, the Fund may invest in a company if (i) it is domiciled in, or the principal trading market for its securities is in, a European country, (ii) it derives 50% or more of its economic value from goods produced, sales made or services performed or has at least 50% of its assets in a European country or (iii) it is a holding company that predominantly holds shares in such companies. The Fund may invest in a variety of countries, industries and sectors and does not attempt to invest a specific percentage of its assets in any given country, industry or sector.

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of small- and mid-sized companies with market capitalizations under $5 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $5 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $5 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $5 billion.

Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $5 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies.

The Fund takes advantage of the Investment Manager’s research and stock-picking capabilities to initially invest in a limited number of companies (generally under 100), offering the potential to provide above-average growth over time.

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may

5

be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

6

• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

• Currency Risk – Securities denominated in non-U.S. dollar currencies are subject to the risk that, for example, if the value of a foreign currency were to decline against the U.S. dollar, such decline would reduce the U.S. dollar value of any securities held by the Fund denominated in that currency.

• Special Situations Risk – Securities of companies that are involved in an initial public offering or a major corporate event, such as a business consolidation or restructuring, may present special risk because of the high degree of uncertainty that can be associated with such events. Securities issued in initial public offerings often are issued by companies that are in the early stages of development, have a history of little or no revenues and may operate at a loss following the offering. It is possible that there will be no active trading market for the securities after the offering, and that the market price of the securities may be subject to significant and unpredictable fluctuations. Investing in special situations may have a magnified effect on the performance of funds with small amounts of assets.

7

Performance Information

Because the Fund commenced investment operations on August 19, 2011, no year-by-year total return bar chart or average annual total return table is being presented. The year-by year-total return bar chart and the average annual total return table will be provided after the Fund has annual returns for at least one calendar year.

Recent performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

8

Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Managers

Andreas Waldburg-Wolfegg

Lead manager since inception in August 2011.

Stephen Kusmierczak, CFA

Co-manager since inception in August 2011.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

9

Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once

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posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Transactions in Derivatives

Although the Fund may execute transactions in derivative instruments, such as hedging transactions in specific foreign currencies, it generally does not do so. The Fund may, however, engage in limited currency forward transactions designed broadly to align the currency exposure of the Fund with the country weightings reflected in the Fund’s primary benchmark.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact

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that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

The Fund may hold up to 20% of its assets in cash under normal circumstances. Because the Fund commenced operations on August 19, 2011 and has only been in operation for a short time, its portfolio is relatively small and significant cash inflows may temporarily cause the Fund to have an increased cash position as the Investment Manager works to invest cash holdings pursuant to the Fund’s principal investment strategies.

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Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 1.19% of average daily net assets of the Fund.

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual report to shareholders for the fiscal period ended June 30, 2012.

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Portfolio Managers

Information about the Investment Manager’s portfolio managers who are primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about each portfolio manager’s compensation, other accounts managed by each portfolio manager and each portfolio manager’s ownership of securities in the Fund.

Andreas Waldburg-Wolfegg

Lead manager since inception in August 2011.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 2002. Vice President of the Trust since 2011. Mr. Waldburg-Wolfegg began his investment career in 1993 and earned an M.A. from the University of St. Andrews, Scotland.

Stephen Kusmierczak, CFA

Co-manager since inception in August 2011.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 2001. Vice President of the Trust since 2011. Mr. Kusmierczak began his investment career in 1999 and earned a B.A. from Bowdoin College and an M.P.A. from Princeton University, Woodrow Wilson School of Public and International Affairs.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In

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addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

Expense Reimbursement Arrangements

The Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that the ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rate of 1.36% of the Fund’s average daily net assets attributable to Class R5 shares, through November 8, 2013. The Investment Manager may recoup any fees waived and/or expenses reimbursed with respect to any share class of the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in this prospectus, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This expense arrangement may only be modified or amended with approval from all parties to such arrangements, including the Fund and the Investment Manager.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Related Performance Information

The Fund commenced investment operations on August 19, 2011 and thus has less than one full calendar year of performance information. The table below sets forth historical performance information for Wanger European Smaller Companies Fund (WESC), an open-end fund organized under the laws of Ireland that is managed by the Fund’s portfolio managers on behalf of the Adviser. WESC has substantially similar investment objectives, principal investment strategies and investment policies as the Fund. Andreas Waldburg-Wolfegg has been lead portfolio manager of WESC since 2005 and was a co-portfolio manager of WESC from 2003 until becoming lead portfolio manager in 2005. Stephen Kusmierczak has been co-portfolio manager of WESC since 2005. WESC is the only fund or account managed by the Investment Manager with objectives, strategies and restrictions that are substantially similar to those of the Fund.

WESC was established on June 9, 1997 and is not registered under the 1940 Act, and thus is not subject to the diversification requirements, investment restrictions, investment limitations, distribution requirements and other mandates that the Fund is subject to under the 1940 Act and Subchapter M of the Internal Revenue Code. WESC’s returns may have been lower had it been regulated as a mutual fund under the federal securities and tax laws. In addition, the net expenses of WESC are lower than the net expenses of Class C shares of the Fund (which do not pay a front-end sales charge but may pay a contingent deferred sales charge), and WESC’s net expenses at times may have been lower than the net expenses of the Fund’s other share classes. If WESC’s net expenses were the same expenses as the net expenses of the Fund’s various share classes, WESC’s performance may have been lower than the performance shown below. As of December 31, 2011, the net asset value of WESC was approximately $22.8 million. The Fund is significantly smaller than WESC, which may affect the Fund’s performance.

The table below compares the performance of WESC with that of the HSBC Smaller European Companies Index (the HSBC Small Europe Index), which is representative of the performance of smaller European companies. The HSBC Small Europe Index is a weighted combination of the HSBC Smaller Europe (ex-United Kingdom) Index and the HSBC Smaller United Kingdom Index.

The performance information for WESC is provided to illustrate the past performance of the Investment Manager in managing a portfolio that is substantially similar to the Fund. The returns shown below were calculated in accordance with Global Investment Performance Standards (GIPS^®); they have not been audited. The WESC performance information shown below does not represent the performance of Columbia Acorn European Fund, and it should not be interpreted as an indication or guarantee of how Columbia Acorn European Fund will perform in the future. Past performance is no indication of future results.

Average Annual Total Return as of December 31, 2011

	1 year			5 years			10 years*
WESC annualized returns before taxes		-14.94	%		-4.83	%		6.51	%
The HSBC Smaller European Companies Index (reflects no deductions for fess, expenses or taxes)		-18.43	%		-5.61	%		5.77	%

* Messrs. Waldburg-Wolfegg and Kusmierczak have served as lead manager and co-manager, respectively since 2005. Prior to 2005, Leah Zell, an investment professional previously employed by the Investment Manager, served as lead portfolio manager of WESC.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R5 shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

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qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

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investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) — (Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

44

Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

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For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

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• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• If at the end of the taxable year more than 50% of the value of the Fund’s assets consists of securities of foreign corporations, and the Fund makes a special election, you will generally be required to include in income your share of the foreign taxes paid by the Fund. You may be able to either deduct this amount from your income or claim it as a foreign tax credit. There is no assurance that the Fund will make a special election for a taxable year, even if it is eligible to do so.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis,

49

holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

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Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1832-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn^® Fund

Ticker Symbols

Class R4 Shares CEARX

Class R5 Shares CRBRX

Class Y Shares CRBYX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn Fund	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	5
Performance Information	8
Investment Manager and Portfolio Manager(s)	10
Purchase and Sale of Fund Shares	10
Tax Information	10
Payments to Broker-Dealers and Other Financial Intermediaries	10
Additional Investment Strategies and Policies	11
Management of the Fund	14
Board of Trustees	14
Primary Service Providers	14
Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest	16
Certain Legal Matters	17
Choosing a Share Class	18
The Funds	18
Summary of Share Class Features	18
Sales Charges and Commissions	21
Reductions/Waivers of Sales Charges	26
Distribution and Service Fees	28
Selling Agent Compensation	29
Buying, Selling and Exchanging Shares	31
Share Price Determination	31
Transaction Rules and Policies	32
Buying Shares	37
Selling Shares	42
Exchanging Shares	43
Distributions and Taxes	46

Acorn^® is a service mark owned and registered by Columbia Acorn Trust. Columbia^SM, Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

    Investment Objective

    Fees and Expenses of the Fund

    Principal Investment Strategies

    Principal Risks

    Performance Information

    Other Roles and Relationships of Ameriprise Financial and its Affiliates - Certain Conflicts of Interest

2

Columbia Acorn Fund

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class R5 Shares		Class Y Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class R5 Shares			Class Y Shares
Management fees		0.64	%		0.64	%		0.64	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%		0.00	%
Other expenses(a)		0.20	%		0.12	%		0.07	%
Total annual Fund operating expenses		0.84	%		0.76	%		0.71	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

3

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4, Class R5 or Class Y shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Based on the assumptions listed above, your costs would be:

	1 year		3 years		5 years		10 years
Class R4 Shares	$	86	$	268	$	466	$	1,037
Class R5 Shares	$	78	$	243	$	422	$	942
Class Y Shares	$	73	$	227	$	395	$	883

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 18% of the average value of its portfolio.

4

Principal Investment Strategies

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of small- and mid-sized companies with market capitalizations under $5 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $5 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $5 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $5 billion. Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $5 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies.

The Fund invests the majority of its assets in U.S. companies, but also may invest up to 33% of its total assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom) and in emerging markets (for example, China, India and Brazil).

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

5

• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

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Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

7

Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class R4, Class R5 and Class Y shares of the Fund had not commenced operations prior to the date of this prospectus; therefore, performance information for these classes is not yet available. The performance of the Fund’s Class Z shares, which have been outstanding longer than any other share class of the Fund, is shown in the bar chart and average annual total return table. Except for differences in annual returns resulting from differences in expenses, Class R4, Class R5 and Class Y shares would have annual returns substantially similar to those of Class Z shares, which are not offered in this prospectus, because all classes of the Fund’s shares invest in the same portfolio of securities.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

Year by Year Total Return (%) as of December 31 Each Year*

The bar chart below shows you how the performance of the Fund’s Class Z shares has varied from year to year.

* Year-to-date return as of September 30, 2012: 14.49%

Best and Worst Quarterly Returns During this Period

Best:	2nd quarter 2009:	20.90	%
Worst:	4th quarter 2008:	-25.11	%

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Average Annual Total Return as of December 31, 2011

The table compares the Fund’s returns for each period with those of the Russell 2500 Index, the Fund’s primary benchmark, the Standard & Poor’s (S&P) 500^® Index and the Russell 2000 Index. The Russell 2500 Index measures the performance of the 2,500 smallest companies in the Russell 3000 Index, which represents approximately 17% of the total market capitalization of the Russell 3000 Index. The S&P 500^® Index tracks the performance of 500 widely held, large-capitalization U.S. stocks. Although the Fund typically invests in small and mid-sized companies, the comparison to the S&P 500^® Index is presented to show performance against a widely recognized market index. The Russell 2000 Index measures the performance of the 2,000 smallest companies in the Russell 3000 Index, which represents approximately 10% of the total market capitalization of the Russell 3000 Index. The Russell 2000 Index shows how the Fund’s performance compares to a widely recognized broad based index of companies with somewhat lower capitalization than the Fund’s primary benchmark.

	1 year			5 years			10 years
Class Z shares returns before taxes		-4.61	%		2.12	%		8.24	%
Class Z shares returns after taxes on distributions		-5.23	%		1.58	%		7.66	%
Class Z shares returns after taxes on distributions and sale of Fund shares		-2.13	%		1.81	%		7.25	%
Russell 2500 Index (reflects no deductions for fees, expenses or taxes)		-2.51	%		1.24	%		6.57	%
S&P 500® Index (reflects no deductions for fees, expenses or taxes)		2.11	%		-0.25	%		2.92	%
Russell 2000 Index (reflects no deductions for fees, expenses or taxes)		-4.18	%		0.15	%		5.62	%

The after-tax returns shown in the table above are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or individual retirement accounts (IRAs).

Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

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Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Managers

Charles P. McQuaid, CFA

Lead manager or co-manager since 1995. Service with the Fund since 1978.

Robert A. Mohn, CFA

Co-manager since 2003. Service with the Fund since 1992.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. The Class Y minimum initial investment amount is $500,000 for omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account; there is no Class Y minimum initial investment amount for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the account. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

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Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once

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posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

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Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

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Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 0.64% of average daily net assets of the Fund.

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual report to shareholders for the fiscal period ended June 30, 2012.

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Portfolio Managers

Information about the Investment Manager’s portfolio managers who are primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about each portfolio manager’s compensation, other accounts managed by each portfolio manager and each portfolio manager’s ownership of securities in the Fund.

Charles P. McQuaid, CFA

Lead manager or co-manager since 1995. Service with the Fund since 1978.

President of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1978; President of the Trust since 2003 and Trustee since 1992. Mr. McQuaid began his investment career in 1976 and earned a B.B.A. from the University of Massachusetts and an M.B.A. from the University of Chicago.

Robert A. Mohn, CFA

Co-manager since 2003. Service with the Fund since 1992.

Portfolio Manager and Director of Domestic Research of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1992. Vice President of the Trust since 1997. Mr. Mohn began his investment career in 1983 and earned a B.S. from Stanford University and an M.B.A. from the University of Chicago.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4, Class R5 and Class Y shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1)Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1)Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1)Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

21

qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a  % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a  % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

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investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) —(Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

43

Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

46

For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

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• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• If at the end of the taxable year more than 50% of the value of the Fund’s assets consists of securities of foreign corporations, and the Fund makes a special election, you will generally be required to include in income your share of the foreign taxes paid by the Fund. You may be able to either deduct this amount from your income or claim it as a foreign tax credit. There is no assurance that the Fund will make a special election for a taxable year, even if it is eligible to do so.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis,

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holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

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Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1448-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn International^®

Ticker Symbols

Class R4 Shares CCIRX

Class Y Shares CCYIX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn International	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	4
Principal Risks	4
Performance Information	7
Investment Manager and Portfolio Manager(s)	9
Purchase and Sale of Fund Shares	9
Tax Information	9
Payments to Broker-Dealers and Other Financial Intermediaries	9
Additional Investment Strategies and Policies	10
Management of the Fund	13
Board of Trustees	13
Primary Service Providers	13
Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest	15
Certain Legal Matters	16
Choosing a Share Class	17
The Funds	17
Summary of Share Class Features	17
Sales Charges and Commissions	20
Reductions/Waivers of Sales Charges	25
Distribution and Service Fees	27
Selling Agent Compensation	28
Buying, Selling and Exchanging Shares	30
Share Price Determination	30
Transaction Rules and Policies	31
Buying Shares	36
Selling Shares	41
Exchanging Shares	42
Distributions and Taxes	45

Acorn International^® is a service mark owned and registered by Columbia Acorn Trust. Columbia^SM , Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

	Investment Objective
	Fees and Expenses of the Fund
	Principal Investment Strategies
	Principal Risks
	Performance Information
	Other Roles and Relationships of Ameriprise Financial and its Affiliates - Certain Conflicts of Interest

2

Columbia Acorn International

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class Y Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class Y Shares
Management fees		0.76	%		0.76	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%
Other expenses(a)		0.23	%		0.10	%
Total annual Fund operating expenses		0.99	%		0.86	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4 or Class Y shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Based on the assumptions listed above, your costs would be:

	1 year		3 years		5 years		10 years
Class R4 Shares	$	101	$	315	$	547	$	1,213
Class Y Shares	$	88	$	274	$	477	$	1,061

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 32% of the average value of its portfolio.

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Principal Investment Strategies

Under normal circumstances, the Fund invests at least 75% of its total assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom) and in emerging markets (for example, China, India and Brazil).

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of small- and mid-sized companies with market capitalizations under $5 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $5 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $5 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $5 billion.

Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $5 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies.

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

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• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

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Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

6

Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class R4 and Class Y shares of the Fund had not commenced operations prior to the date of this prospectus; therefore, performance information for these classes is not yet available. The performance of the Fund’s Class Z shares, which have been outstanding longer than any other share class of the Fund, is shown in the bar chart and average annual total return table. Except for differences in annual returns resulting from differences in expenses, Class R4 and Class Y shares would have annual returns substantially similar to those of Class Z shares, which are not offered in this prospectus, because all classes of the Fund’s shares invest in the same portfolio of securities.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

Year by Year Total Return (%)as of December 31 Each Year*

The bar chart below shows you how the performance of the Fund’s Class Z shares has varied from year to year.

* Year-to-date return as of September 30, 2012: 16.66%

Best and Worst Quarterly Returns During this Period

Best:	2nd quarter 2009:	33.30	%
Worst:	3rd quarter 2008:	-23.68	%

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Average Annual Total Return as of December 31, 2011

The table compares the Fund’s returns, for each period, with those of the Standard & Poor’s (S&P) Global Ex-U.S. Between $500 Million and $5 Billion^® Index, the Fund’s primary benchmark, the S&P Global Ex-U.S. SmallCap^® Index and the MSCI Europe, Australasia and Far East (EAFE) Index (Net). The S&P Global Ex-U.S. Between $500 Million and $5 Billion^® Index is a subset of the broad market selected by the index sponsor that represents the mid- and small-cap developed and emerging markets, excluding the United States. The S&P Global Ex-U.S. SmallCap^® Index is an unmanaged index consisting of the bottom 20% of institutionally investable capital of developed and emerging countries, excluding the United States. The performance of the S&P Global Ex-U.S. Small Cap^® Index is provided to show how the Fund’s performance compares to foreign market performance with a similar geographic distribution and wider market cap range than the Fund’s primary benchmark. The MSCI EAFE Index (Net) is a capitalization-weighted index that tracks the total return of common stocks in 22 developed-market countries within Europe, Australasia and the Far East. The performance of the MSCI EAFE Index (Net) is provided to show how the Fund’s performance compares to a widely recognized broad based index of foreign market performance.

	1 year			5 years			10 years
Class Z shares returns before taxes		-14.06	%		0.20	%		10.27	%
Class Z shares returns after taxes on distributions		-14.63	%		-0.32	%		9.71	%
Class Z shares returns after taxes on distributions and sale of Fund shares		-8.88	%		0.20	%		9.18	%
S&P Global Ex-U.S. Between $500 Million and $5 Billion® Index (reflects no deductions for fees, expenses or taxes)		-16.94	%		-0.58	%		11.10	%
S&P Global Ex-U.S. SmallCap® Index (reflects no deductions for fees, expenses or taxes)		-17.40	%		-2.14	%		10.33	%
MSCI EAFE Index (Net) (reflects reinvested dividends net of withholding taxes but reflects no deductions for fees, expenses or other taxes)		-12.14	%		-4.72	%		4.67	%

The after-tax returns shown in the table above are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or individual retirement accounts (IRAs).

Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

8

Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Managers

P. Zachary Egan, CFA

Co-manager since 2003. Service with the Fund since 1999.

Louis J. Mendes, CFA

Co-manager since 2003. Service with the Fund since 2001.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class Y minimum initial investment amount is $500,000 for omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account; there is no Class Y minimum initial investment amount for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the account. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

9

Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once

10

posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Transactions in Derivatives

Although the Fund may execute transactions in derivative instruments, such as hedging transactions in specific foreign currencies, it generally does not do so. The Fund may, however, engage in limited currency forward transactions designed broadly to align the currency exposure of the Fund with the country weightings reflected in the Fund’s primary benchmark.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact

11

that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

12

Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 0.76% of average daily net assets of the Fund.

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual report to shareholders for the fiscal period ended June 30, 2012.

13

Portfolio Managers

Information about the Investment Manager’s portfolio managers who are primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about each portfolio manager’s compensation, other accounts managed by each portfolio manager and each portfolio manager’s ownership of securities in the Fund.

P. Zachary Egan, CFA

Co-manager since 2003. Service with the Fund since 1999.

Portfolio Manager and Director of International Research of the Adviser; associated with the Adviser or its predecessors as an investment professional since 1999. Vice President of the Trust since 2003. Mr. Egan began his investment career in 1999 and earned a B.A. from Middlebury College and an M.A. from the University of Chicago.

Louis J. Mendes, CFA

Co-manager since 2003. Service with the Fund since 2001.

Portfolio Manager and Analyst of the Adviser; associated with the Adviser or its predecessors as an investment professional since 2001. Vice President of the Trust since 2003. Mr. Mendes began his investment career in 1986 and earned a B.A. from Columbia University and an M.I.M. from the American Graduate School of International Management.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4 and Class Y shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

20

qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a  % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

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investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) —(Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

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Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

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For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

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• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• If at the end of the taxable year more than 50% of the value of the Fund’s assets consists of securities of foreign corporations, and the Fund makes a special election, you will generally be required to include in income your share of the foreign taxes paid by the Fund. You may be able to either deduct this amount from your income or claim it as a foreign tax credit. There is no assurance that the Fund will make a special election for a taxable year, even if it is eligible to do so.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis,

47

holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

48

Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1568-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn International Select^SM

Ticker Symbols

Class R4 Shares CILRX

Class R5 Shares CRIRX

Class Y Shares CSIRX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn International Select	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	5
Performance Information	8
Investment Manager and Portfolio Manager(s)	10
Purchase and Sale of Fund Shares	10
Tax Information	10
Payments to Broker-Dealers and Other Financial Intermediaries	10
Additional Investment Strategies and Policies	11
Management of the Fund	14
Board of Trustees	14
Primary Service Providers	14
Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest	16
Certain Legal Matters	17
Choosing a Share Class	18
The Funds	18
Summary of Share Class Features	18
Sales Charges and Commissions	21
Reductions/Waivers of Sales Charges	26
Distribution and Service Fees	28
Selling Agent Compensation	29
Buying, Selling and Exchanging Shares	31
Share Price Determination	31
Transaction Rules and Policies	32
Buying Shares	37
Selling Shares	42
Exchanging Shares	43
Distributions and Taxes	46

Columbia^SM, Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

	Investment Objective
	Fees and Expenses of the Fund
	Principal Investment Strategies
	Principal Risks
	Performance Information
	Other Roles and Relationships of Ameriprise Financial and its Affiliates - Certain Conflicts of Interest

2

Columbia Acorn International Select

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class R5 Shares		Class Y Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class R5 Shares			Class Y Shares
Management fees		0.94	%		0.94	%		0.94	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%		0.00	%
Other expenses(a)		0.27	%		0.19	%		0.14	%
Total annual Fund operating expenses		1.21	%		1.13	%		1.08	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

3

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4, Class R5 or Class Y shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Based on the assumptions listed above, your costs would be:

	1 year		3 years		5 years		10 years
Class R4 Shares	$	123	$	384	$	665	$	1,466
Class R5 Shares	$	115	$	359	$	622	$	1,375
Class Y Shares	$	110	$	343	$	595	$	1,317

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 44% of the average value of its portfolio.

4

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 65% of its net assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom). The Fund also may invest up to 35% of its total assets in companies in emerging markets (for example, China, India and Brazil). The Fund generally invests in at least three countries other than the United States but may invest up to 25% of its total assets in securities of U.S. issuers.

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of small- and mid-sized companies with market capitalizations under $25 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $25 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $25 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $25 billion.

Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $25 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies. The Fund also may invest in larger-sized companies.

The Fund takes advantage of the Investment Manager’s research and stock-picking capabilities to invest in a limited number of foreign companies (generally between 40-60), offering the potential to provide above-average growth over time.

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller

5

companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity

6

than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

7

Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class R4, Class R5 and Class Y shares of the Fund had not commenced operations prior to the date of this prospectus; therefore, performance information for these classes is not yet available. The performance of the Fund’s Class Z shares, which have been outstanding longer than any other share class of the Fund, is shown in the bar chart and average annual total return table. Except for differences in annual returns resulting from differences in expenses, Class R4, Class R5 and Class Y shares would have annual returns substantially similar to those of Class Z shares, which are not offered in this prospectus, because all classes of the Fund’s shares invest in the same portfolio of securities.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

Year by Year Total Return (%) as of December 31 Each Year*

The bar chart below shows you how the performance of the Fund’s Class Z shares has varied from year to year.

* Year-to-date return as of September 30, 2012: 24.28%

Best and Worst Quarterly Returns During this Period

Best:	2nd quarter 2009:	23.44	%
Worst:	3rd quarter 2008:	-24.76	%

8

Average Annual Total Return as of December 31, 2011

The table compares the Fund’s returns, for each period, with those of the Standard & Poor’s (S&P) Developed Ex-U.S. Between $2 Billion and $10 Billion^® Index, the Fund’s primary benchmark, and the MSCI Europe, Australasia and Far East (EAFE) Index (Net). The S&P Developed Ex-U.S. Between $2 Billion and $10 Billion^® Index is a subset of the broad market selected by the index sponsor that represents the mid-cap developed market excluding the United States. The MSCI EAFE Index (Net) is a capitalization-weighted index that tracks the total return of common stocks in 22 developed-market countries within Europe, Australasia and the Far East. The performance of the MSCI EAFE Index (Net) is provided to show how the Fund’s performance compares to a widely recognized broad based index of foreign market performance.

	1 year			5 years			10 years
Class Z shares returns before taxes		-9.76	%		0.41	%		9.22	%
Class Z shares returns after taxes on distributions		-10.24	%		0.01	%		9.02	%
Class Z shares returns after taxes on distributions and sale of Fund shares		-5.37	%		0.45	%		8.31	%
S&P Developed Ex-U.S. Between $2 Billion and $10 Billion® Index (reflects no deductions for fees, expenses or taxes)		-14.01	%		-3.06	%		8.41	%
MSCI EAFE Index (Net) (reflects reinvested dividends net of withholding taxes but reflects no deductions for fees, expenses or other taxes)		-12.14	%		-4.72	%		4.67	%

The after-tax returns shown in the table above are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or individual retirement accounts (IRAs).

Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

9

Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Manager

Christopher J. Olson, CFA

Lead manager or co-manager since 2001.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. The Class Y minimum initial investment amount is $500,000 for omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account; there is no Class Y minimum initial investment amount for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the account. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

10

Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once

11

posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Transactions in Derivatives

Although the Fund may execute transactions in derivative instruments, such as hedging transactions in specific foreign currencies, it generally does not do so. The Fund may, however, engage in limited currency forward transactions designed broadly to align the currency exposure of the Fund with the country weightings reflected in the Fund’s primary benchmark.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact

12

that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

13

Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 0.94% of average daily net assets of the Fund.

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual report to shareholders for the fiscal period ended June 30, 2012.

Portfolio Manager

Information about the Investment Manager’s portfolio manager who is primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about the portfolio manager’s compensation, other accounts managed by the portfolio manager and the portfolio manager’s ownership of securities in the Fund.

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Christopher J. Olson, CFA

Lead manager or co-manager since 2001.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 2001. Vice President of the Trust since 2001. Mr. Olson began his investment career in 1988 and earned a B.A. from Middlebury College, an M.B.A. from the Wharton School, University of Pennsylvania, and an M.A. from the School of Arts and Sciences, University of Pennsylvania.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

Expense Reimbursement Arrangements

The Investment Manager has voluntarily agreed to reimburse expenses so that the Fund’s ordinary operating expenses (excluding certain expenses described below), after giving effect to any balance credits or overdraft charges from the Fund’s custodian, do not exceed the annual rates of 1.45%, 1.33% and 1.28% of the Fund’s average daily net assets attributable to Class R4, Class R5 and Class Y shares, respectively. The following expenses are excluded from the Fund’s ordinary operating expenses when calculating the cap, and therefore will be paid by the Fund: taxes, brokerage commissions, interest and extraordinary expenses. The Investment Manager or the Fund may modify or discontinue this arrangement on 30 days notice.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4, Class R5 and Class Y shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

21

qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

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investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) —(Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

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Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

46

For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

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• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• If at the end of the taxable year more than 50% of the value of the Fund’s assets consists of securities of foreign corporations, and the Fund makes a special election, you will generally be required to include in income your share of the foreign taxes paid by the Fund. You may be able to either deduct this amount from your income or claim it as a foreign tax credit. There is no assurance that the Fund will make a special election for a taxable year, even if it is eligible to do so.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis,

48

holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

49

Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1578-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn Select^SM

Ticker Symbols

Class R4 Shares CSSRX

Class R5 Shares CSLRX

Class Y Shares CSLYX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn Select	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	5
Performance Information	8
Investment Manager and Portfolio Manager(s)	10
Purchase and Sale of Fund Shares	10
Tax Information	10
Payments to Broker-Dealers and Other Financial Intermediaries	10
Additional Investment Strategies and Policies	11
Management of the Fund	14
Board of Trustees	14
Primary Service Providers	14
Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest	17
Certain Legal Matters	18
Choosing a Share Class	19
The Funds	19
Summary of Share Class Features	19
Sales Charges and Commissions	22
Reductions/Waivers of Sales Charges	27
Distribution and Service Fees	29
Selling Agent Compensation	30
Buying, Selling and Exchanging Shares	32
Share Price Determination	32
Transaction Rules and Policies	33
Buying Shares	38
Selling Shares	43
Exchanging Shares	44
Distributions and Taxes	47

Columbia^SM, Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

    Investment Objective

    Fees and Expenses of the Fund

    Principal Investment Strategies

    Principal Risks

    Performance Information

    Other Roles and Relationships of Ameriprise Financial and its Affiliates - Certain Conflicts of Interest

2

Columbia Acorn Select

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class R5 Shares		Class Y Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class R5 Shares			Class Y Shares
Management fees		0.82	%		0.82	%		0.82	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%		0.00	%
Other expenses(a)		0.22	%		0.14	%		0.09	%
Total annual Fund operating expenses		1.04	%		0.96	%		0.91	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

3

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4, Class R5 or Class Y shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Based on the assumptions listed above, your costs would be:

	1 year		3 years		5 years		10 years
Class R4 Shares	$	106	$	331	$	574	$	1,271
Class R5 Shares	$	98	$	306	$	531	$	1,178
Class Y Shares	$	93	$	290	$	504	$	1,120

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 21% of the average value of its portfolio.

4

Principal Investment Strategies

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of companies with market capitalizations under $20 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $20 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $20 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $20 billion.

Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $20 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies.

The Fund invests the majority of its assets in U.S. companies, but also may invest up to 33% of its total assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom) and in emerging markets (for example, China, India and Colombia).

The Fund takes advantage of the Investment Manager’s research and stock-picking capabilities to invest in a limited number of companies (generally between 30-60), offering the potential to provide above-average growth over time.

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Fund may also invest in companies that the Investment Manager believes have good operational fundamentals but that the Investment Manager believes are undervalued due to negative investor sentiment related to company-specific or market-related conditions. Investments in turnaround and development stage companies may also be made when the Investment Manager believes potential returns outweigh risks of losses.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management

5

teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to

6

experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

• Opportunistic Investing Risk – Undervalued securities involve the risk that they may never reach their expected full market value, either because the market fails to recognize the security’s intrinsic worth or the expected value was misgauged. Undervalued securities also may decline in price even though the Investment Manager believes they are already undervalued. Turnaround companies may never improve their fundamentals, may take much longer than expected to improve, or may improve much less than expected. Development stage companies could fail to develop and deplete their assets, resulting in large percentage losses.

7

Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class R4, Class R5 and Class Y shares of the Fund had not commenced operations prior to the date of this prospectus; therefore, performance information for these classes is not yet available. The performance of the Fund’s Class Z shares, which have been outstanding longer than any other share class of the Fund, is shown in the bar chart and average annual total return table. Except for differences in annual returns resulting from differences in expenses, Class R4, Class R5 and Class Y shares would have annual returns substantially similar to those of Class Z shares, which are not offered in this prospectus, because all classes of the Fund’s shares invest in the same portfolio of securities.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

Year by Year Total Return (%) as of December 31 Each Year*

The bar chart below shows you how the performance of the Fund’s Class Z shares has varied from year to year.

* Year-to-date return as of September 30, 2012: 14.81%

Best and Worst Quarterly Returns During this Period

Best:	2nd quarter 2009:	28.11	%
Worst:	4th quarter 2008:	-30.14	%

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Average Annual Total Return as of December 31, 2011

The table compares the Fund’s returns for each period with those of the Standard & Poor’s (S&P) MidCap 400^® Index, the Fund’s primary benchmark, and the S&P 500^® Index. The S&P MidCap 400^® Index is a market value-weighted index that tracks the performance of 400 mid-cap U.S. companies. The S&P 500^® Index tracks the performance of 500 widely held, large-capitalization U.S. stocks. Although the Fund typically invests in companies with market capitalizations under $20 billion at the time of investment, the comparison to the S&P 500^® Index is presented to show performance against a widely recognized market index.

	1 year			5 years			10 years
Class Z shares returns before taxes		-16.37	%		-1.07	%		6.05	%
Class Z shares returns after taxes on distributions		-16.87	%		-1.33	%		5.77	%
Class Z shares returns after taxes on distributions and sale of Fund shares		-10.60	%		-0.95	%		5.27	%
S&P MidCap 400® Index (reflects no deductions for fees, expenses or taxes)		-1.73	%		3.32	%		7.04	%
S&P 500® Index (reflects no deductions for fees, expenses or taxes)		2.11	%		-0.25	%		2.92	%

The after-tax returns shown in the table above are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or individual retirement accounts (IRAs).

Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

9

Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Managers

Ben Andrews

Lead manager since 2004. Service with the Fund since inception in 1998.

Robert A. Chalupnik, CFA

Co-manager since 2011. Service with the Fund since 2000.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. The Class Y minimum initial investment amount is $500,000 for omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account; there is no Class Y minimum initial investment amount for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the account. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

10

Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers

and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Status as Diversified Investment Company

The Fund was previously registered as a non-diversified investment company. Effective January 31, 2012, the Fund changed its classification from non-diversified to diversified. The Fund will not be able to become non-diversified unless it seeks and obtains the approval of shareholders.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

11

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact

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that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

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Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 0.82% of average daily net assets of the Fund.

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual

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report to shareholders for the fiscal period ended June 30, 2011.

Portfolio Managers

Information about the Investment Manager’s portfolio managers who are primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about each portfolio manager’s compensation, other accounts managed by each portfolio manager and each portfolio manager’s ownership of securities in the Fund.

Ben Andrews

Lead manager since 2004. Service with the Fund since inception in 1998.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1998. Vice President of the Trust since 2004. Mr. Andrews began his investment career in 1993 and earned a B.S.E.E. from the University of Florida and an M.B.A. from Loyola University of Chicago.

Robert A. Chalupnik, CFA

Co-manager since 2011. Service with the Fund since 2000.

Portfolio Manager and Analyst of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1998. Vice President of the Trust since May 2011. Mr. Chalupnik began his investment career in 1994 and earned a B.S. and an M.B.A. from the University of Illinois.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

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The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

Expense Reimbursement Arrangements

The Investment Manager has voluntarily agreed to reimburse expenses so that the Fund’s ordinary operating expenses (excluding certain expenses described below), after giving effect to any balance credits or overdraft charges from the Fund’s custodian, do not exceed the annual rate of 1.35%, 1.30% and 1.25% of the Fund’s average daily net assets attributable to Class R4, Class R5 and Class Y shares. The following expenses are excluded from the Fund’s ordinary operating expenses when calculating the cap, and therefore will be paid by the Fund: taxes, brokerage commissions, interest and extraordinary expenses. The Investment Manager or the Fund may modify or discontinue this arrangement on 30 days notice.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

17

Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4, Class R5 and Class Y shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion  Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion  Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

21

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion  Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares- Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

22

qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

28

investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) —(Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

44

Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

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For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

48

• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis, holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment

49

income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

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Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1588-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Acorn USA^®

Ticker Symbols

Class R4 Shares CUSAX

Class R5 Shares CYSRX

Class Y Shares CUSYX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Acorn USA	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	5
Performance Information	7
Investment Manager and Portfolio Manager(s)	9
Purchase and Sale of Fund Shares	9
Tax Information	9
Payments to Broker-Dealers and Other Financial Intermediaries	9
Additional Investment Strategies and Policies	10
Management of the Fund	13
Board of Trustees	13
Primary Service Providers	13
Other Roles and Relationships of Ameriprise Financial and its Affiliates – Certain Conflicts of Interest	16
Certain Legal Matters	17
Choosing a Share Class	18
The Funds	18
Summary of Share Class Features	18
Sales Charges and Commissions	21
Reductions/Waivers of Sales Charges	26
Distribution and Service Fees	28
Selling Agent Compensation	29
Buying, Selling and Exchanging Shares	31
Share Price Determination	31
Transaction Rules and Policies	32
Buying Shares	37
Selling Shares	42
Exchanging Shares	43
Distributions and Taxes	46

Acorn USA^® is a service mark owned and registered by Columbia Acorn Trust. Columbia^SM , Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

    Investment Objective

    Fees and Expenses of the Fund

    Principal Investment Strategies

    Principal Risks

    Performance Information

    Other Roles and Relationships of Ameriprise Financial and its Affiliates – Certain Conflicts of Interest

2

Columbia Acorn USA

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class R5 Shares		Class Y Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class R5 Shares			Class Y Shares
Management fees		0.86	%		0.86	%		0.86	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%		0.00	%
Other expenses(a)		0.22	%		0.14	%		0.09	%
Total annual Fund operating expenses		1.08	%		1.00	%		0.95	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

3

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4, Class R5 or Class Y shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Based on the assumptions listed above, your costs would be:

	1 year		3 years		5 years		10 years
Class R4 Shares	$	110	$	343	$	595	$	1,317
Class R5 Shares	$	102	$	318	$	552	$	1,225
Class Y Shares	$	97	$	303	$	526	$	1,166

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 20% of the average value of its portfolio.

4

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in U.S. companies.

Under normal circumstances, the Fund invests a majority of its net assets in the common stock of small- and mid-sized companies with market capitalizations under $5 billion at the time of investment. However, if the Fund’s investments in such companies represent less than a majority of its net assets, the Fund may continue to hold and to make additional investments in an existing company in its portfolio even if that company’s capitalization has grown to exceed $5 billion. Except as noted above, under normal circumstances, the Fund may invest in other companies with market capitalizations above $5 billion, provided that immediately after that investment a majority of its net assets would be invested in companies with market capitalizations under $5 billion.

Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), believes that stocks of companies with market capitalizations under $5 billion, which generally are not as well known by financial analysts as larger companies, may offer higher return potential than stocks of larger companies.

The Investment Manager typically seeks companies with:

• A strong business franchise that offers growth potential.

• Products and services that give the company a competitive advantage.

• A stock price the Investment Manager believes is reasonable relative to the assets and earning power of the company.

The Investment Manager may sell a portfolio holding if the security reaches the Investment Manager’s price target, if the company has a deterioration of fundamentals, such as failing to meet key operating benchmarks, or if the Investment Manager believes other securities are more attractive. The Investment Manager also may sell a portfolio holding to fund redemptions.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Market Risk – Market risk refers to the possibility that the market values of securities that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

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• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

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Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class R4, Class R5 and Class Y shares of the Fund had not commenced operations prior to the date of this prospectus; therefore, performance information for these classes is not yet available. The performance of the Fund’s Class Z shares, which have been outstanding longer than any other share class of the Fund, is shown in the bar chart and average annual total return table. Except for differences in annual returns resulting from differences in expenses, Class R4, Class R5 and Class Y shares would have annual returns substantially similar to those of Class Z shares, which are not offered in this prospectus, because all classes of the Fund’s shares invest in the same portfolio of securities.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

Year by Year Total Return (%) as of December 31 Each Year*

The bar chart below shows you how the performance of the Fund’s Class Z shares has varied from year to year.

* Year-to-date return as of September 30, 2012: 15.33%

Best and Worst Quarterly Returns During this Period

Best:	3rd quarter 2009:	23.55	%
Worst:	4th quarter 2008:	-27.96	%

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Average Annual Total Return as of December 31, 2011

The table compares the Fund’s returns for each period with those of the Russell 2000 Index. This index measures the performance of the 2,000 smallest companies in the Russell 3000 Index, which represents approximately 10% of the total market capitalization of the Russell 3000 Index.

	1 year			5 years			10 years
Class Z shares returns before taxes		-4.95	%		0.82	%		6.30	%
Class Z shares returns after taxes on distributions		-5.04	%		0.52	%		6.02	%
Class Z shares returns after taxes on distributions and sale of Fund shares		-3.10	%		0.69	%		5.54	%
Russell 2000 Index (reflects no deductions for fees, expenses or taxes)		-4.18	%		0.15	%		5.62	%

The after-tax returns shown in the table above are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or individual retirement accounts (IRAs).

Returns after taxes on distributions and sale of Fund shares are higher than before-tax returns for certain periods shown because they reflect the tax benefit of capital losses realized on the redemption of Fund shares.

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Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Manager

Robert A. Mohn, CFA

Lead manager since inception in 1996.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. The Class Y minimum initial investment amount is $500,000 for omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account; there is no Class Y minimum initial investment amount for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the account. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

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Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Fund may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website, www.columbiamanagement.com, as described below. Once

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posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. The top 15 holdings are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

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Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

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Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 0.86% of average daily net assets of the Fund.

A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual

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report to shareholders for the fiscal period ended June 30, 2011.

Portfolio Manager

Information about the Investment Manager’s portfolio manager who is primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about the portfolio manager’s compensation, other accounts managed by the portfolio manager and the portfolio manager’s ownership of securities in the Fund.

Robert A. Mohn, CFA

Lead manager since inception in 1996.

Portfolio Manager and Director of Domestic Research of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1992. Vice President of the Trust since 1997.

Mr. Mohn began his investment career in 1983 and earned a B.S. from Stanford University and an M.B.A. from the University of Chicago.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

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The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4, Class R5 and Class Y shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •        1.00% CDSC if redeemed within 12 months of purchase, and •        0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

21

qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

27

investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) —(Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund’s NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund’s assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

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rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

43

Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

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For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

47

• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis, holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment

48

income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

49

Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1608-99 A (11/12)

Prospectus

November 8, 2012

Columbia Acorn Family of Funds

Managed By Columbia Wanger Asset Management, LLC

Columbia Thermostat Fund^SM

Ticker Symbols

Class R4 Shares CTORX

Class R5 Shares CQTRX

Class Y Shares CYYYX

As with all mutual funds, the Securities and Exchange Commission has not approved or disapproved these securities or passed upon the adequacy of this prospectus. Any representation to the contrary is a criminal offense.

Table of Contents

Columbia Thermostat Fund	3
Investment Objective	3
Fees and Expenses of the Fund	3
Principal Investment Strategies	5
Principal Risks	7
Performance Information	13
Investment Manager and Portfolio Manager(s)	15
Purchase and Sale of Fund Shares	15
Tax Information	15
Payments to Broker-Dealers and Other Financial Intermediaries	15
Additional Investment Strategies and Policies	16
Portfolio Funds Summary	19
Management of the Fund	24
Board of Trustees	24
Primary Service Providers	24
Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest	27
Certain Legal Matters	28
Choosing a Share Class	29
The Funds	29
Summary of Share Class Features	29
Sales Charges and Commissions	32
Reductions/Waivers of Sales Charges	37
Distribution and Service Fees	39
Selling Agent Compensation	40
Buying, Selling and Exchanging Shares	42
Share Price Determination	42
Transaction Rules and Policies	43
Buying Shares	48
Selling Shares	53
Exchanging Shares	54
Distributions and Taxes	57

Columbia^SM, Columbia Management^®, and the Columbia Management Logo^® are service marks owned and/or registered by Ameriprise Financial, Inc.

Icons Guide

	Investment Objective
	Fees and Expenses of the Fund
	Principal Investment Strategies
	Principal Risks
	Performance Information
	Other Roles and Relationships of Ameriprise Financial and its Affiliates – Certain Conflicts of Interest

2

Columbia Thermostat Fund

Investment Objective

The Fund seeks long-term capital appreciation.

Fees and Expenses of the Fund

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

Shareholder Fees (fees paid directly from your investment)

	Class R4 Shares		Class R5 Shares		Class Y Shares
Maximum sales charge (load) imposed on purchases, as a % of offering price		None		None		None
Maximum deferred sales charge (load) imposed on redemptions, as a % of the lower of the original purchase price or net asset value		None		None		None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

	Class R4 Shares			Class R5 Shares			Class Y Shares
Management fees		0.10	%		0.10	%		0.10	%
Distribution and/or service (Rule 12b-1) fees		0.00	%		0.00	%		0.00	%
Other expenses(a)		0.32	%		0.24	%		0.19	%
Acquired fund fees and expenses		0.65	%		0.65	%		0.65	%
Total annual Fund operating expenses		1.07	%		0.99	%		0.94	%
Fee waivers and/or reimbursements		-0.17	%		-0.07	%		-0.07	%
Total annual Fund operating expenses after fee waivers and/or reimbursements		0.90	%		0.92	%		0.87	%

^(a)  Other expenses are based on estimated amounts for the current fiscal year.

^(b)  Columbia Wanger Asset Management, LLC (the Investment Manager) has contractually agreed to waive fees and reimburse certain expenses of the Fund so that ordinary operating expenses (excluding distribution and service fees, interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies) do not exceed the annual rates of 0.25% of the Fund’s average daily net assets for Class R4, 0.27% for Class R5 and 0.22% for Class Y, through November 8, 2013. The figure shown here is the amount of expected waivers and/or reimbursements. This fee and expense arrangement may only be modified or amended with approval from all parties to such arrangement, including the Fund and the Investment Manager.

3

Example

The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.

The example illustrates the hypothetical expenses that you would incur over the time periods indicated, and assumes that:

• you invest $10,000 in Class R4, Class R5 or Class Y shares of the Fund for the periods indicated,

• your investment has a 5% return each year, and

• the Fund’s total annual operating expenses remain the same as shown in the table above.

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire on November 8, 2013, they are only reflected in the 1 year example and the first year of the 3, 5 and 10 year examples.

Based on the assumptions listed above, your costs would be:

	1 year		3 years		5 years		10 years
Class R4 Shares	$	92	$	323	$	574	$	1,290
Class R5 Shares	$	94	$	308	$	540	$	1,207
Class Y Shares	$	89	$	293	$	513	$	1,148

Remember this is an example only. Your actual costs may be higher or lower.

Portfolio Turnover

The Fund will indirectly bear the expenses associated with portfolio turnover of the underlying Portfolio Funds in which the Fund invests. Each Portfolio Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A Portfolio Fund’s higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when its shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 130% of the average value of its portfolio.

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Principal Investment Strategies

The Fund pursues its investment objective by investing in other mutual funds. As a “fund of funds,” under normal circumstances, the Fund allocates at least 95% of its net assets (stock/bond assets) among a selected group of stock and bond mutual funds (Portfolio Funds) according to the current level of Standard & Poor’s (S&P) 500^® Index. Generally, when the S&P 500^® Index goes up in relation to predetermined ranges set by Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager), the Fund sells a portion of its stock funds and invests more in the bond funds and when the S&P 500^® Index goes down in relation to the ranges, the Fund increases its investment in the stock funds. Under normal circumstances, the Fund may invest up to 5% of net assets plus any cash received that day in cash, high quality short-term paper and government securities.

Many asset allocation funds typically move assets from stocks to bonds when the market goes up, and from bonds to stocks when the market goes down. Most asset allocation funds are run by sophisticated investment professionals, who make subjective decisions based on economic and financial data and complex graphs of market behavior. By contrast, the day-to-day investment decisions for the Fund are made according to a single predetermined rule. The temperature in your house is run by a single rule: your thermostat turns on the furnace if your house is too cold or turns on the air conditioner if your house is too warm. This Fund works the same way, so it is named Columbia Thermostat Fund.

Because the Fund invests according to a pre-set program, there is no need for subjective day-to-day management. Although another successful asset allocation strategy might do better than the Fund, the Fund is designed for those who doubt the wisdom of trying to “time” the market and are unsure of the long-term trend of the stock market. The Fund takes psychology out of investing; it avoids the temptation to buy more stocks because the stock market is currently going up or to sell stocks because the market is declining. The Fund operates continuously and substantially automatically, subject to periodic review of the pre-set program by the Investment Manager and the Fund’s Board of Trustees. As described more fully below, the Investment Manager has the authority to review the structure and allocation ranges of the stock/bond allocation table and to make any changes considered appropriate.

The Investment Manager chooses the Portfolio Funds to provide participation in the major sectors of the stock and bond markets. If you believe that the stock market will tend to go up most of the time, then you should probably own a fully invested stock fund and use a buy-and-hold strategy. Buy-and-hold was an excellent strategy in the 1982-1999 bull market. However, there have been long periods in the past when buy-and-hold was not the best strategy, such as 1930-1954 and 1969-1981, when the market fluctuated but did not make significant new highs. The Fund may be a good investment choice for you if you believe that the market may fluctuate in a trading range for many years, that a remarkable bull market ended early in 2000 and that the market may not reach significant new highs for many years.

The Fund invests its stock/bond assets among the Portfolio Funds according to an asset allocation table. The current allocation table is set forth below.

Stock/Bond Allocation Table

	How the Fund will Invest the Stock/Bond Assets
Level of the S&P 500® Index	Stock Percentage			Bond Percentage
over 1750		10	%		90	%
over 1700-1750		15	%		85	%
over 1650-1700		20	%		80	%
over 1600-1650		25	%		75	%
over 1550-1600		30	%		70	%
over 1500-1550		35	%		65	%
over 1450-1500		40	%		60	%
over 1400-1450		45	%		55	%
over 1350-1400		50	%		50	%
over 1300-1350		55	%		45	%
over 1250-1300		60	%		40	%
over 1200-1250		65	%		35	%
over 1150-1200		70	%		30	%
over 1100-1150		75	%		25	%
over 1050-1100		80	%		20	%
over 1000-1050		85	%		15	%
1000 and under		90	%		10	%

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When the S&P 500^® Index moves into a new band on the table, the Fund promptly will rebalance the stock/bond mix to reflect the new S&P 500^® Index price level by redeeming shares of some Portfolio Funds and purchasing shares of other Portfolio Funds. The only exception will be a “31-day Rule”; in order to reduce taxable events, after the Fund has increased its percentage allocation to either stock funds or bond funds, it will not decrease that allocation for at least 31 days. Following a change in the Fund’s stock/bond mix, if the S&P 500^® Index remains within the same band for a while, normal market fluctuations will change the values of the Fund’s holdings of stock Portfolio Funds and bond Portfolio Funds. The Investment Manager will invest cash flows from sales (or redemptions) of Fund shares to bring the stock/bond mix back toward the allocation percentages for that S&P 500^® Index band. For example, if the S&P 500^® Index is in the 1150-1200 band, and the value of the holdings of the stock Portfolio Funds has dropped to 68% of the value of the holdings of all Portfolio Funds, the Investment Manager would invest new cash in the stock Portfolio Funds (or cash for redemptions would come from the bond Portfolio Funds). If the 31-day Rule is in effect, the Investment Manager will invest new cash at the stock/bond percentage allocation as of the latest rebalancing.

As an illustrative example, suppose the following:

Date	Level of the S&P 500® Index	How the Fund will invest the Stock/ Bond Assets
Nov. 1	We begin when the market is 1380	50% stocks, 50% bonds
Dec. 1	The S&P 500® goes to 1401	rebalance 45% stocks, 55% bonds
Dec. 6	The S&P 500® drops back to 1390	no reversal for 31 days
Jan. 2	The S&P 500® is at 1352	rebalance 50% stocks, 50% bonds
Jan. 20	The S&P 500® drops to 1349	rebalance 55% stocks, 45% bonds
	The market has made a continuation move by going through a second action level, not a reversal move, so the 31-day Rule does not apply in this case.
Jan. 30	The S&P 500® goes up to 1355	no reversal for 31 days
Feb. 20	The S&P 500® is at 1360	rebalance 50% stocks, 50% bonds

The following table shows the seven stock Portfolio Funds and three bond Portfolio Funds that the Fund currently uses in its “fund of funds” structure and the current allocation percentage for each Portfolio Fund within the stock or bond category. As described more fully below, the Investment Manager may substitute or add additional Portfolio Funds at any time, including funds introduced after the date of this prospectus. The allocation percentage within each stock/bond category is achieved by rebalancing the investments within the category whenever the S&P 500^® Index moves into a new band on the allocation table, subject to the 31-day Rule described above. The Fund does not liquidate its investment in one Portfolio Fund in order to invest in another Portfolio Fund except in connection with a rebalancing due to a move of the S&P 500^® Index into a new band (or due to a change by the Investment Manager in the stock/bond allocation table to the Portfolio Funds or to the relative allocation among them). Until a subsequent rebalancing, the Fund’s investments in, and redemptions from, the stock Portfolio Funds or the bond Portfolio Funds are allocated among the Portfolio Funds in a manner that will reduce any deviation of the relative values of the Fund’s holdings of the Funds from the allocation percentages shown below.

Allocation of Stock/Bond Assets Within Asset Classes

Stock Funds	Type of Fund	Allocation
Columbia Acorn Fund	Small/Mid-cap growth		15	%
Columbia Acorn Select	Mid-cap growth		10	%
Columbia Acorn International	Small/Mid-cap international growth		20	%
Columbia Dividend Income Fund	Large-cap value		20	%
Columbia Large Cap Enhanced Core Fund	Large-cap blend		10	%
Columbia Contrarian Core Fund	Large-cap blend		15	%
Columbia Select Large Cap Growth Fund	Large-cap growth		10	%
Total			100	%
Bond Funds	Type of Fund	Allocation
Columbia Intermediate Bond Fund	Intermediate-term bonds		50	%
Columbia Income Opportunities Fund	High-yield bonds		30	%
Columbia U.S. Treasury Index Fund	U.S. Treasury notes/bonds		20	%

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Total 100 % 

The Investment Manager has the authority to review the Portfolio Funds and the relative stock/bond allocation percentages among them and to make any changes considered appropriate.

Each of the Portfolio Funds is currently managed by the Investment Manager or its affiliates. The Fund does not pay any sales load on its purchases of shares of the Portfolio Funds. On an annual basis, or on an “emergency” basis if necessary, the Investment Manager reviews the structure, allocation percentages and Portfolio Funds and makes any changes considered appropriate. The Investment Manager typically addresses the following questions:

• Should the stock/bond allocation table be revised (perhaps because the stock market has made a long-term move outside of the bands set forth above)?

• Should there be a change in the Portfolio Funds or should there be a change in the percentage allocations among the stock/bond funds (perhaps because of a change of portfolio managers, change of investment style, change in relative valuation or a reorganization of a Portfolio Fund)?

Any such changes by the Investment Manager are expected to be infrequent.

Principal Risks

• Investment Strategy Risk – The Fund’s manager uses the principal investment strategies and other investment strategies to seek to achieve the Fund’s investment objective. There is no assurance that the Fund will achieve its investment objective. Investment decisions may not produce the expected returns, may cause the Fund’s shares to lose value or may cause the Fund to underperform other funds with similar investment objectives.

• Allocation Risk – The Fund uses an asset allocation strategy in pursuit of its investment objective. There is a risk that the Fund’s allocation among asset classes or investments will cause the Fund’s shares to lose value or cause the Fund to underperform other funds with similar investment objectives, or that the investments themselves will not produce the returns expected.

• Investing in Other Funds Risk – The performance of the underlying fund(s) in which the Fund invests could be adversely affected if other entities that invest in the same underlying fund(s) make relatively large investments or redemptions in the underlying fund(s). In addition, because the expenses and costs of the underlying fund(s) are shared by investors in the underlying fund, redemptions by other investors in the underlying fund could result in decreased economies of scale and increased operating expenses for the underlying fund. The Fund, and its shareholders, indirectly bear a portion of the expenses of the underlying fund(s). These transactions might also result in higher brokerage, tax or other costs for the Fund. This risk may be particularly important when one investor owns a substantial portion of any underlying fund. In addition, the Investment Manager has the authority to change the underlying fund(s) in which the Fund invests or to change the percentage of the Fund’s investments allocated to each underlying fund. If an underlying fund pays fees to the Investment Manager or its affiliates, such as advisory fees, this could result in the Investment Manager having a potential conflict of interest in selecting the underlying fund(s) in which the Fund invests or in determining the percentage of the Fund’s investments allocated to each underlying fund. In addition, the underlying funds are themselves subject to Investment Strategy Risk.

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The Fund is subject indirectly to the following risks of the Portfolio Funds:

• Market Risk – Market risk refers to the possibility that the market values of securities that a Portfolio Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall because of factors affecting individual companies, industries or sectors, or the markets as a whole, reducing the value of an investment in the Portfolio Fund. Accordingly, an investment in a Portfolio Fund could lose money over short or even long periods, or fail to increase in value. The market values of the securities the Portfolio Fund holds also can be affected by changes or perceived changes in U.S. or foreign economies and financial markets, and the liquidity of these securities, among other factors. In general, equity securities tend to have greater price volatility than debt securities.

• Interest Rate Risk – Debt securities are subject to interest rate risk. In general, if prevailing interest rates rise, the values of debt securities will tend to fall, and if interest rates fall, the values of debt securities will tend to rise. Changes in the value of a debt security usually will not affect the amount of income a Portfolio Fund receives from it but may affect the value of the Portfolio Fund’s shares. Interest rate risk is generally greater for debt securities with longer maturities/durations.

• Credit Risk – Credit risk applies to most debt securities, but is generally less of a factor for obligations backed by the “full faith and credit” of the U.S. Government. A Portfolio Fund could lose money if the issuer of a debt security owned by the Fund is unable or perceived to be unable to pay interest or repay principal when it becomes due. Various factors could affect the issuer’s actual or perceived willingness or ability to make timely interest or principal payments, including changes in the issuer’s financial condition or in general economic conditions. Debt securities backed by an issuer’s taxing authority may be subject to legal limits on the issuer’s power to increase taxes or otherwise to raise revenue, or may be dependent on legislative appropriation or government aid. Certain debt securities are backed only by revenues derived from a particular project or source, rather than by an issuer’s taxing authority, and thus may have a greater risk of default.

• Low and Below Investment Grade Securities Risk – Debt securities with the lowest investment grade rating (e.g., BBB by Standard & Poor’s, a division of the McGraw-Hill Companies, Inc. (S&P), or Fitch, Inc. (Fitch) or Baa by Moody’s Investors Service, Inc. (Moody’s)), or that are below investment grade (which are commonly referred to as “junk bonds”) (e.g., BB or below by S&P or Fitch or Ba by Moody’s) and unrated securities of comparable quality are more speculative than securities with higher ratings and may experience greater price fluctuations. These securities tend to be more sensitive to credit risk than higher-rated securities, particularly during a downturn in the economy, which is more likely to weaken the ability of the issuers to make principal and interest payments on these securities. These securities typically pay a premium – a higher interest rate or yield – because of the increased risk of loss, including default. These securities also are generally less liquid than higher-rated securities. The securities ratings provided by Moody’s, S&P and Fitch are based on analyses by these ratings agencies of the credit quality of the securities and may not take into account every risk related to whether interest or principal will be timely repaid.

• Value Securities Risk – Value securities are securities of companies that may have experienced, for example, adverse business, industry or other developments or may be subject to special risks that have caused the securities to be out of favor and, in turn, potentially undervalued. The market value of a portfolio security may not meet the Investment Manager’s future value assessment of that security, or may decline. There is also a risk that it may take longer than expected for the value of these investments to rise to the believed value. In addition, value securities, at times, may not perform as well as growth securities or the stock market in general, and may be out of favor with investors for varying periods of time.

• Growth Securities Risk – Because growth securities typically trade at a higher multiple of earnings than other types of securities, the market values of growth securities may be more sensitive to changes in current or expected earnings than the market values of other types of securities. In addition, growth securities, at times, may not perform as well as value securities or the stock market in general, and may be out of favor with investors for varying periods of time.

• Sector Risk – At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a broadly related group of industries

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within an economic sector. Companies in the same economic sector may be similarly affected by economic or market events, making the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

• Foreign Securities Risk – Foreign securities are subject to special risks as compared to securities of U.S. issuers. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates may impact the value of foreign securities denominated in foreign currencies, or in U.S. dollars, without a change in the intrinsic value of those securities. Foreign securities may be less liquid than domestic securities so that the Portfolio Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial fees and other fees are also generally higher for foreign securities. The Portfolio Fund may have limited or no legal recourse in the event of default with respect to certain foreign securities, including those issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which could reduce the amount of income and capital gains available to distribute to shareholders. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events, possible imposition of currency exchange controls or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. The Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies (“foreign sub-custodians”), as permitted under the Investment Company Act of 1940 (the 1940 Act). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to the Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of the Fund, may abstain from voting proxies in markets that require share blocking.

• Emerging Market Securities Risk – Securities issued by foreign governments or companies in emerging market countries, like Russia and those in Eastern Europe, the Middle East, Asia, Latin America or Africa, are more likely to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk. In addition, emerging market countries are more likely to experience instability resulting, for example, from rapid social, political and economic development. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity than more developed countries. Emerging market securities tend to be more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade, which makes them more sensitive to world commodity prices and economic downturns in other countries.

Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible

9

foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of the Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of the Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that the Fund may lose its ownership rights. In such a case, it may be difficult for the Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in Russia.

• Smaller Company Securities Risk – Securities of small- or mid-capitalization companies (“smaller companies”) can, in certain circumstances, have a higher potential for gains than securities of large-capitalization companies but may also have more risk. For example, smaller companies may be more vulnerable to market downturns and adverse business or economic events than larger, more established companies because they may have more limited financial resources and business operations. These companies are also more likely than large-capitalization companies (“larger companies”) to have more limited product lines and operating histories and to depend on smaller management teams. Their securities may trade less frequently and in smaller volumes and may be less liquid and fluctuate more sharply in value than securities of larger companies. In cases where the Fund takes significant positions in smaller companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be prolonged and result in investment losses. In addition, some smaller companies may not be widely followed by the investment community, which can lower the demand for their stocks.

• Index Risk – U.S. Treasury Index Fund’s value will generally decline when the performance of its targeted index declines. Because U.S. Treasury Index Fund is designed to track an index before fees and expenses, U.S. Treasury Index Fund cannot purchase other securities that may help offset declines in its index. In addition, because U.S. Treasury Index Fund may not hold all issues included in its index, may not always be fully invested, and bears advisory, administrative and other expenses and transaction costs in trading securities, U.S. Treasury Index Fund’s performance may fail to match the performance of its targeted index, after taking expenses into account. It is not possible to invest directly in an index.

• U.S. Government Obligations Risk – While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or may be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities

10

issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. For example, securities issued by the Federal Home Loan Mortgage Corporation, the Federal National Mortgage Association and the Federal Home Loan Banks are neither insured nor guaranteed by the U.S. Government. These securities may be supported by the ability to borrow from the U.S. Treasury or only by the credit of the issuing agency, authority, instrumentality or enterprise and, as a result, are subject to greater credit risk than securities issued or guaranteed by the U.S. Treasury. Securities guaranteed by the Federal Deposit Insurance Corporation under its Temporary Liquidity Guarantee Program (TLGP) are subject to certain risks, including whether such securities will continue to trade in line with recent experience in relation to treasury and government agency securities in terms of yield spread and the volatility of such spread, as well as uncertainty as to how such securities will trade in the secondary market and whether that market will be liquid or illiquid. The TLGP is subject to change.

• Derivatives Risk – Derivatives are financial contracts whose values are, for example, based on (or “derived” from) traditional securities (such as a stock or bond), assets (such as a commodity like gold or a foreign currency), reference rates (such as LIBOR) or market indices (such as the S&P 500^® Index). Derivatives involve special risks and may result in losses or may limit a Portfolio Fund’s potential gain from favorable market movements. Derivative strategies often involve leverage, which may exaggerate a loss, potentially causing a Portfolio Fund to lose more money than it would have lost had it invested in the underlying security or other asset. The values of derivatives may move in unexpected ways, especially in unusual market conditions, and may result in increased volatility, among other consequences. The use of derivatives may also increase the amount of taxes payable by shareholders holding shares in a taxable account. Other risks arise from a Portfolio Fund’s potential inability to terminate or to sell derivative positions. A liquid secondary market may not always exist for the Portfolio Fund’s derivative positions at times when the Portfolio Fund might wish to terminate or to sell such positions. Over-the-counter instruments (investments not traded on an exchange) may be illiquid, and transactions in derivatives traded in the over-the-counter market are subject to the risk that the other party will not meet its obligations. The use of derivatives also involves the risks of mispricing or improper valuation and that changes in the value of the derivative may not correlate perfectly with the underlying security, asset, reference rate or index. A Portfolio Fund also may not be able to find a suitable derivative transaction counterparty, and thus may be unable to engage in derivative transactions when it is deemed favorable to do so, or at all. U.S. federal legislation has recently been enacted that provides for new clearing, margin, reporting and registration requirements for participants in the derivatives market. While the ultimate impact is not yet clear, these changes could restrict and/or impose significant costs or other burdens upon the Fund’s participation in derivatives transactions. For more information on the risks of derivative investments and strategies, see the Statement of Additional Information.

• Convertible Securities Risk – Certain Portfolio Funds invest in convertible securities, which are subject to the usual risks associated with debt securities, such as interest rate risk and credit risk. Convertible securities also react to changes in the value of the common stock into which they convert. Because the value of a convertible security can be influenced by both interest rates and the common stock’s market movements, a convertible security generally is not as sensitive to interest rates as a similar debt security, and generally will not vary in value in response to other factors to the same extent as the underlying common stock. In the event of a liquidation of the issuing company, holders of convertible securities would typically be paid before the company’s common stockholders but after holders of any senior debt obligations of the company. A Portfolio Fund may be forced to convert a convertible security before it otherwise would choose to do so, which may decrease the Portfolio Fund’s return.

• Non-Diversified Mutual Fund Risk – If a Portfolio Fund is non-diversified, that Portfolio Fund generally may invest a greater percentage of its total assets in the securities of fewer issuers than may a “diversified” fund. This increases the risk that a change in the value of any one investment held by the non-diversified Portfolio Fund could affect the overall value of the Portfolio Fund more than it would affect that of a diversified fund holding a greater number of investments. Accordingly, a non-diversified Portfolio Fund’s value will likely be more volatile than the value of more diversified funds. A Portfolio Fund that is non-diversified may not operate as a non-diversified fund at all times.

• Technology Sector Risk – Companies in the technology sector are subject to significant competitive pressures, such as aggressive pricing of their products or services, new

11

market entrants, competition for market share, short product cycles due to an accelerated rate of technological developments and the potential for limited earnings and/or falling profit margins. These companies also face the risks that new services, equipment or technologies will not be accepted by consumers and businesses or will become rapidly obsolete. These factors can affect the profitability of technology companies and, as a result, the value of their securities. Also, patent protection is integral to the success of many companies in the technology sector, and profitability can be affected materially by, among other things, the cost of obtaining (or failing to obtain) patent approvals, the cost of litigating patent infringement and the loss of patent protection for products (which significantly increases pricing pressures and can materially reduce profitability with respect to such products). In addition, many technology companies have limited operating histories. Prices of these companies’ securities historically have been more volatile than other securities, especially over the short term. Because certain Portfolio Funds invest a significant portion of their net assets in the equity securities of technology companies, a Portfolio Fund’s price may be more volatile than a fund that is invested in a more diverse range of market sectors.

• Health Care Sector Risk – Companies in the health care sector are subject to extensive government regulation. Their profitability can be affected significantly and adversely by restrictions on government reimbursement for medical expenses, government approval of medical products and services, competitive pricing pressures, an increased emphasis on outpatient and other alternative services and other factors. Patent protection is integral to the success of companies in the health care sector, and profitability can be affected materially by, among other things, the cost of obtaining (or failing to obtain) patent approvals, the cost of litigating patent infringement and the loss of patent protection for medical products (which significantly increases pricing pressures and can materially reduce profitability with respect to such products). Companies in the health care sector also potentially are subject to extensive product liability and other similar litigation. Companies in the health care sector are affected by the rising cost of medical products and services, and the effects of such rising costs can be particularly pronounced for companies that are dependent on a relatively limited number of products or services. Medical products also frequently become obsolete due to industry innovation or other causes. Because certain Portfolio Funds invest a significant portion of their net assets in the equity securities of health care companies, a Portfolio Fund’s price may be more volatile than a fund that is invested in a more diverse range of market sectors.

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Performance Information

The following bar chart and table show you how the Fund has performed in the past, and can help you understand the risks of investing in the Fund. Class R4, Class R5 and Class Y shares of the Fund had not commenced operations prior to the date of this prospectus; therefore, performance information for these classes is not yet available. The performance of the Fund’s Class Z shares, which have been outstanding longer than any other share class of the Fund, is shown in the bar chart and average annual total return table. Except for differences in annual returns resulting from differences in expenses, Class R4, Class R5 and Class Y shares would have annual returns substantially similar to those of Class Z shares, which are not offered in this prospectus, because all classes of the Fund’s shares invest in the same portfolio of securities.

The Fund’s past performance (before and after taxes) is no guarantee of how the Fund will perform in the future. Updated performance information can be obtained by calling toll-free 800.345.6611 or visiting www.columbiamanagement.com.

Year by Year Total Return (%) as of December 31 Each Year*

The bar chart below shows you how the performance of the Fund’s Class Z shares has varied from year to year.

* Year-to-date return as of September 30, 2012: 11.99%

Best and Worst Quarterly Returns During this Period

Best:	2nd quarter 2009:	19.33	%
Worst:	4th quarter 2008:	-19.26	%

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Average Annual Total Return as of December 31, 2011

The table compares the Fund’s returns for each period with those of the S&P 500^® Index, the Fund’s primary benchmark for equity securities, the Barclays U.S. Aggregate Bond Index, the Fund’s primary benchmark for debt securities, the Lipper Flexible Portfolio Funds Index and a 50/50 Blended Benchmark. The S&P 500^® Index tracks the performance of 500 widely held, large-capitalization U.S. stocks. The Barclays U.S. Aggregate Bond Index is a market value-weighted index that tracks the daily price, coupon, pay-downs, and total return performance of fixed-rate, publicly placed, dollar-denominated, and non-convertible investment grade debt issues with at least $250 million par amount outstanding and with at least one year to final maturity. The Lipper Flexible Portfolio Funds Index is an equal-weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper, and shows how the Fund’s performance compares with the returns of an index of funds with similar investment objectives. The 50/50 Blended Benchmark was established by the Investment Manager to show how the Fund’s performance compares to an equally weighted custom composite of the Fund’s primary equity and primary debt benchmarks, the S&P 500^® Index and the Barclays U.S. Aggregate Bond Index, respectively. The percentage of the Fund’s assets allocated to underlying stock and bond Portfolio Funds will vary, and accordingly the composition of the Fund’s portfolio will not always reflect the composition of the 50/50 Blended Benchmark.

	1 year			5 years			Life of Fund (September 25, 2002)
Class Z shares returns before taxes		4.85	%		4.21	%		7.51	%
Class Z shares returns after taxes on distributions		3.80	%		3.12	%		6.26	%
Class Z shares returns after taxes on distributions and sale of Fund shares		3.15	%		3.06	%		5.97	%
S&P 500® Index (reflects no deductions for fees, expenses or taxes)		2.11	%		-0.25	%		6.85	%
Barclays U.S. Aggregate Bond Index (reflects no deductions for fees, expenses or taxes)		7.84	%		6.50	%		5.33	%
Lipper Flexible Portfolio Funds Index (reflects no deductions for taxes)		-1.16	%		2.02	%		7.10	%
50/50 Blended Benchmark (an equally weighted custom composite of the Fund’s primary benchmarks for equity and debt securities, established by the Investment Manager; reflects no deductions for fees, expenses or taxes)		5.28	%		3.54	%		6.43	%

The after-tax returns shown in the table above are calculated using the highest historical individual U.S. federal marginal income tax rates and do not reflect the impact of state, local or foreign taxes. Your actual after-tax returns will depend on your personal tax situation and may differ from those shown in the table. In addition, the after-tax returns shown in the table do not apply to shares held in tax-deferred accounts such as 401(k) plans or individual retirement accounts (IRAs).

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Investment Manager and Portfolio Manager(s)

Investment Manager

Columbia Wanger Asset Management, LLC

Portfolio Manager

Charles P. McQuaid, CFA

Lead manager or co-manager since inception in 2002.

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day on the Columbia Funds’ website at www.columbiamanagement.com, by mail (Columbia Funds, c/o Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081) or by telephone at 800.422.3737. You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. There is no minimum initial investment for Class R4 shares. The Class R5 minimum initial investment amount is $100,000 for combined underlying accounts of eligible registered investment advisers; there is no Class R5 minimum initial investment amount for omnibus retirement plans. The Class Y minimum initial investment amount is $500,000 for omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account; there is no Class Y minimum initial investment amount for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the account. There is no minimum additional investment for any share class.

Tax Information

The Fund normally distributes net investment income and net realized capital gains, if any, to shareholders. These distributions are generally taxable to you as ordinary income or capital gains, unless you are a tax-exempt investor or otherwise investing through a tax-advantaged account (such as a 401(k) plan or an IRA). If you are investing through a tax-advantaged account, you may be taxed upon withdrawals from that account.

Payments to Broker-Dealers and Other Financial Intermediaries

If you purchase the Fund through a broker-dealer or other financial intermediary (such as a bank), the Fund and its related companies – including the Investment Manager, Columbia Management Investment Distributors, Inc. (the Distributor) and Columbia Management Investment Services Corp. (the Transfer Agent) – may pay the intermediary for the sale of Fund shares and related services. These payments may create a conflict of interest by influencing the broker-dealer or other intermediary and your financial advisor to recommend the Fund over another investment. Ask your financial advisor or visit your financial intermediary’s website for more information.

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Additional Investment Strategies and Policies

This section describes certain strategies and policies that the Fund may utilize in pursuit of its investment objective, and describes some additional factors and risks involved with investing in the Fund.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses are comprised of (a) investment management fees; (b) distribution and/or service (Rule 12b-1) fees; and (c) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class. Typically, expenses will vary by class if the services they relate to are different for different share classes. For additional information about fees, see Management of the Fund – Primary Service Providers; Choosing a Share Class – Distribution and Service Fees; and Choosing a Share Class – Selling Agent Compensation.

FUNDamentals^TM

Other Expenses

“Other Expenses” consist of the fees the Fund pays to its administrator, custodian, transfer agent, auditors, lawyers and trustees, costs relating to compliance and miscellaneous expenses. Generally, these expenses are the same for each share class and are allocated on a pro rata basis across all share classes. Transfer agent fees, however, are class specific. They differ by share class because the shareholder services provided to each share class may be different. Accordingly, the differences in “Other Expenses” among share classes are primarily the result of the different transfer agent fees applicable to each share class. For details on the transfer agent fees paid by each share class, see Choosing a Share Class – Selling Agent Compensation.

Changing the Fund’s Investment Objective and Policies

The Fund’s investment objective and non-fundamental investment policies (including its principal and additional investment strategies) can be changed by the Fund’s Board of Trustees (the Board) without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Statement of Additional Information (SAI), may be changed only with Board and shareholder approval in accordance with the voting requirements of the Investment Company Act of 1940 (the 1940 Act). For additional information about changing the Fund’s fundamental and non-fundamental investment policies, see About the Funds’ Investments – Fundamental and Non-Fundamental Investment Policies in the SAI.

Investment Guidelines

As a general matter, and except as specifically described in the discussion of the Fund’s principal investment strategies in this prospectus, whenever an investment policy or limitation states a percentage of the Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with that percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of the security or asset. For these purposes, the Fund determines the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

Holding Other Kinds of Investments

The Fund may hold investments that are not part of its principal investment strategies. These investments and their risks are described below and in the Statement of Additional Information (SAI). The Fund may choose not to invest in certain securities described in this prospectus and in the SAI, although it has the ability to do so.

Lending of Portfolio Securities

The Portfolio Funds may lend portfolio securities to approved broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. A Portfolio Fund may lose money from securities lending if, for example, it is delayed in or prevented from selling the collateral after the loan is made or recovering the securities loaned or if it incurs losses on the reinvestment of cash collateral.

Portfolio Holdings Disclosure

A description of the Fund’s policies and procedures with respect to the disclosure of Fund portfolio securities is available in the SAI. The Fund discloses its portfolio holdings on the Columbia Funds’ website,

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www.columbiamanagement.com, as described below. Once posted, the portfolio holdings information will remain available on the website until at least the date on which such Fund files a Form N-CSR or Form N-Q (forms filed with the Securities and Exchange Commission (SEC) that include portfolio holdings information) for the period that includes the date as of which the information is current.

The Fund considers changes in its portfolio holdings to be confidential information. Consequently, Fund policy generally permits the disclosure of portfolio holdings information only after a certain amount of time has passed. The Fund’s complete portfolio holdings are disclosed at www.columbiamanagement.com, approximately 30 calendar days after each month-end. Purchases and sales of portfolio securities can take place at any time, so the portfolio holdings information available on the website may not always be current. A more detailed description of the Fund’s policies and procedures governing disclosure of portfolio information is available in the SAI, which can be accessed on the Fund’s website or by calling us at 800.345.6611.

Investing Defensively

The Fund may from time to time take temporary defensive investment positions that are inconsistent with the Fund’s principal investment strategies in attempting to respond to adverse market, economic, political or other conditions. These investment positions may include, for example, investments in money market instruments or holdings of cash or cash equivalents. The Fund may not achieve its investment objective while it is investing defensively. The Investment Manager currently expects that substantially all of the Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Fund expects to remain substantially exposed to the equity markets.

Use of Benchmarks

Benchmarks are indices that provide some comparative guidance in assessing the Fund’s performance. The Investment Manager selects the benchmarks it believes provide meaningful comparisons for each Fund. However, there may be different or additional indices that more closely reflect the market sectors in which the Fund invests. The Fund’s benchmarks may change from time to time. The benchmarks included in this prospectus are intended only as guideposts for your assessment of the Fund’s performance.

FUNDamentals^TM

Portfolio Holdings Versus the Benchmarks

The Fund does not limit its investments to the securities within its benchmarks, and accordingly the Fund’s holdings may diverge significantly from those of the benchmarks selected by the Investment Manager. In addition, the Fund may invest in securities outside the industry and geographic sectors represented in its benchmarks. The Fund’s weightings in individual securities, and in industry and geographic sectors, may also vary considerably from those of its benchmarks.

Mailings to Households

In order to reduce shareholder expenses the Fund may, if prior consent has been provided, mail only one copy of the Fund’s prospectus and each annual and semi-annual report to those addresses shared by two or more accounts. If you wish to receive individual copies of these documents, call 800.345.6611 or, if your shares are held through a financial intermediary, contact your intermediary directly.

Additional Information on Portfolio Turnover

A mutual fund that replaces, or turns over, more than 100% of its investments in a year is considered to have a high portfolio turnover rate. A high portfolio turnover rate can generate larger distributions of short-term capital gains to shareholders, which for individuals are generally taxable at higher rates than long-term capital gains for U.S. federal income tax purposes. A high portfolio turnover rate can also mean higher brokerage and other transaction costs, which could reduce a fund’s returns. In general, the greater the volume of buying and selling by a fund, the greater the impact that brokerage commissions will have on its returns. However, the Fund may sell securities regardless of how long they’ve been held.

Because Columbia Thermostat Fund is a fund of funds that exchanges shares of the underlying Portfolio Funds at net asset value, the costs associated with the Fund’s portfolio turnover rate are lower than the costs that would be associated with another fund that had the same portfolio turnover rate but directly bore the trading costs of its portfolio

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transactions.

Cash Flows

The timing and magnitude of cash inflows from investors buying Fund shares could prevent the Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors selling Fund shares could require untimely dispositions of portfolio securities or large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact the Fund's performance.

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Portfolio Funds Summary

The table starting below provides a brief overview of the investment objectives and principal investments of the Portfolio Funds in which the Fund invests.

You’ll find more detailed information about each Portfolio Fund’s investment strategies and risks in its prospectus and SAI. Refer to www.columbiamanagement.com or contact your financial advisor for details.

	The Portfolio Fund’s Investment Objective:	About the Portfolio Fund:
Columbia Acorn® Fund	•         seeks long-term capital appreciation.	•         under normal circumstances, invests a majority of its net assets in small- and medium-sized companies with market capitalizations under $5 billion at the time of investment.
		•         invests the majority of its assets in U.S. companies, but also may invest up to 33% of its total assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom) and in emerging markets (for example, China, India and Brazil).
Columbia Acorn International®	•         seeks long-term capital appreciation.	•         under normal circumstances, invests at least 75% of its total assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom) and in emerging markets (for example, China, India and Brazil).
		•         under normal circumstances, invests the majority of its net assets in small- and medium-sized companies with market capitalizations under $5 billion at the time of investment.
Columbia Acorn SelectSM	•         seeks long-term capital appreciation.	•         under normal circumstances, invests a majority of its net assets in companies with market capitalizations under $20 billion at the time of investment.
		•         invests in a limited number of companies (generally between 30-60).
		•         invests the majority of its assets in U.S. companies, but also may invest up to 33% of its total assets in foreign companies in developed markets (for example, Japan, Canada and the United Kingdom) and in emerging markets (for example, China, India and Colombia).

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	The Portfolio Fund’s Investment Objective:	About the Portfolio Fund:
Columbia Contrarian Core Fund	•         seeks total return, consisting of long-term capital appreciation and current income.	•         under normal circumstances, invests at least 80% of its net assets in common stocks and at least 80% of its net assets in equity securities of U.S. companies that have large market capitalizations (generally over $2 billion) that the fund’s investment manager believes are undervalued and have the potential for long-term growth and current income.
		•         may invest up to 20% of its net assets in foreign securities.
		•         the fund’s investment manager combines fundamental and quantitative analysis with risk management in identifying investment opportunities and constructing the fund’s portfolio.
Columbia Dividend Income Fund	•         seeks total return, consisting of current income and capital appreciation.	•         under normal circumstances, invests at least 80% of its net assets in a diversified portfolio of income-producing (dividend-paying) equity securities, which will consist primarily of common stocks but also may include preferred stocks and convertible securities.
		•         may invest in companies that have market capitalizations of any size.
		•         may invest up to 20% of its net assets in debt securities, including securities that, at the time of purchase, are rated low and below investment grade or are unrated but determined to be of comparable quality, which are commonly referred to as “junk bonds.”
		•         may invest up to 20% of its net assets in foreign securities.
		•         the fund’s investment manager combines fundamental and quantitative analysis with risk management in identifying investment opportunities and constructing the fund’s portfolio.

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	The Portfolio Fund’s Investment Objective:	About the Portfolio Fund:
Columbia Income Opportunities Fund	•         seeks to provide shareholders with a high total return through current income and capital appreciation.	•         under normal market conditions, invests primarily in income-producing debt securities, with an emphasis on the higher rated segment of the high-yield (junk bond) market.
		•         purchases only securities rated B or above, or unrated securities believed to be of comparable quality.
		•         up to 25% of net assets may be in foreign investments.
		•         may invest in fixed income securities, including corporate debt securities as well as bank loans, of any maturity and does not seek to maintain a particular dollar-weighted average maturity.
Columbia Intermediate Bond Fund	•         seeks total return, consisting of current income and capital appreciation.	•         under normal circumstances, invests at least 80% of its net assets in bonds, including debt securities issued by the U.S. Government and its agencies, debt securities issued by corporations, mortgage- and other asset-backed securities and dollar-denominated securities issued by foreign governments, companies or other entities.
		•         invests at least 60% of its net assets in debt securities that, at the time of purchase, are rated in at least one of the three highest bond rating categories or are unrated securities determined by the fund’s investment manager to be of comparable quality.
		•         may invest up to 20% of net assets in securities that, at the time of purchase, are below investment grade securities (commonly referred to as “high yield securities” or “junk bonds”) or in unrated securities determined to be of comparable quality.
		•         under normal circumstances, the fund’s dollar-weighted average effective maturity will be between three and ten years.
		•         may invest in derivatives, including futures, forwards, options, swap contracts and other derivative instruments.
		•         may invest in private placements.
		•         may participate in mortgage dollar rolls up to the fund’s then current position in mortgage-backed securities.

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	The Portfolio Fund’s Investment Objective:	About the Portfolio Fund:
Columbia Large Cap Enhanced Core Fund	•         seeks total return before fees and expenses that exceeds the total return of the S&P 500® Index.	•         under normal circumstances, invests at least 80% of its net assets in common stocks that comprise the S&P 500® Index, convertible securities that are convertible into stocks included in that index, and derivatives whose returns are closely equivalent to the returns of the S&P 500® Index or its components.
		•         generally holds fewer stocks than the S&P 500® Index and may hold securities that are not in the S&P 500® Index.
		•         the fund’s investment manager attempts to maintain a portfolio that generally matches the risk characteristics of the S&P 500® Index. The fund’s investment manager will vary the number and percentages of the fund’s holdings in attempting to provide higher returns than the S&P 500® Index and to reduce the potential of underperforming such index over time.
Columbia Select Large Cap Growth Fund	•         seeks long-term capital appreciation.	•         under normal circumstances, invests at least 80% of its net assets in common stocks of U.S. and foreign companies that have market capitalizations in the range of companies in the Russell 1000 Growth Index at the time of purchase (between $1.3 billion and $546.1 billion as of June 30, 2012).
		•         invests primarily in common stocks of companies that the fund’s investment manager believes have the potential for long-term growth.
		•         may invest directly in foreign securities or indirectly through depositary receipts.
		•         will not concentrate its assets in any single industry but may invest more than 25% of its assets in companies conducting business in various industries within an economic sector.
		•         the fund’s investment manager combines fundamental and quantitative analysis with risk management in identifying investment opportunities and constructing the fund’s portfolio.

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	The Portfolio Fund’s Investment Objective:	About the Portfolio Fund:
Columbia U.S. Treasury Index Fund	•         seeks total return that corresponds to the total return of the Citigroup Bond U.S. Treasury Index, before fees and expenses.	•         under normal circumstances, invests at least 80% of its net assets in securities that comprise the Citigroup Bond U.S. Treasury Index, an unmanaged index composed of U.S. Treasury notes and bonds with remaining maturities of at least one year and outstanding principal of at least $25 million and which are included in the Citigroup Broad Investment-Grade Bond Index. Different securities have different weightings in the Citigroup Bond U.S. Treasury Index.
		•         in seeking to match the performance of the Citigroup Bond U.S. Treasury Index, before fees and expenses, the fund’s investment manager attempts to allocate the fund’s assets among securities in the Citigroup Bond U.S. Treasury Index. In determining whether to include a security in the fund’s portfolio, the fund’s investment manager will consider a security’s effect on the fund’s total market value, average coupon rate, and average weighted maturity as compared to the Citigroup Bond U.S. Treasury Index.
		•         attempts to achieve at least a 95% correlation between the performance of the Citigroup Bond U.S. Treasury Index and the fund’s investment results, before fees and expenses.

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Management of the Fund

Board of Trustees

The Fund is governed by the Board. More than 75% of the Fund’s Trustees are independent (Independent Trustees), meaning that they are not “interested persons” of the Fund, as defined in the 1940 Act. The Independent Trustees bring backgrounds in business and academia to their task of working with the Fund’s officers to establish the Fund’s policies and oversee its activities. Among the Trustees’ responsibilities are: selecting the investment adviser for the Fund; negotiating the advisory agreement; reviewing other contracts; approving investment policies; monitoring Fund operations, performance, compliance and costs; and nominating or selecting new Trustees.

Each Trustee serves the Fund for an indefinite term until his or her retirement, resignation, death or removal in accordance with the organizational documents of Columbia Acorn Trust (the Trust). The Trust’s Bylaws generally require that Trustees retire at the end of the calendar year in which they attain the age of 75 years. The last meeting to elect Trustees was held on May 27, 2010. Any Trustee may be removed at a shareholders’ meeting by a vote representing two-thirds of the net asset value of all shares of the Columbia Acorn family of funds (Columbia Acorn Funds). The mailing address for the Trustees and officers is 227 W. Monroe, Suite 3000, Chicago, Illinois 60606.

For more detailed information about the Board, please refer to the SAI.

Primary Service Providers

The Investment Manager, who also serves as the Fund’s administrator (the Administrator), the Distributor and the Transfer Agent are all affiliates of Ameriprise Financial, Inc. (Ameriprise Financial). They currently provide key services to the Fund and various other funds, including the funds using the Columbia brand (Columbia Funds) and the funds using the RiverSource, Threadneedle and Seligman brands (Other Funds), and are paid for providing these services. These service relationships are described below.

Ameriprise Financial is a financial planning and financial services company that has offered investment management and insurance products for more than 110 years.

The Investment Manager

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of September 30, 2012, the Investment Manager had assets under management of approximately $32.2 billion. The Investment Manager is a registered investment adviser and wholly owned subsidiary of Columbia Management Investment Advisers, LLC, which is a wholly owned subsidiary of Ameriprise Financial and the Fund’s sub-administrator (the Sub-Administrator). In addition to serving as an investment adviser to mutual funds, the Investment Manager acts as an investment manager for other institutional accounts.

Subject to oversight by the Board, the Investment Manager manages the day-to-day operations of the Fund, determining what securities and other investments the Fund should buy or sell and executing the Fund’s portfolio transactions. The Investment Manager may also use the research and other expertise of its affiliates and third parties in managing the Fund’s investments.

The Fund pays the Investment Manager a fee for its investment advisory services. The fee is calculated as a percentage of the average daily net assets of the Fund and is paid monthly. For the Fund’s most recent fiscal year, aggregate advisory fees paid to the Investment Manager by the Fund amounted to 0.10% of average daily net assets of the Fund.

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A discussion regarding the basis for the Board’s approval of the Fund’s investment advisory agreement with the Investment Manager is available in the Fund’s semi-annual report to shareholders for the fiscal period ended June 30, 2012.

Portfolio Manager

Information about the Investment Manager’s portfolio manager who is primarily responsible for overseeing the Fund’s investments is shown in the table below. The SAI provides more information about the portfolio manager’s compensation, other accounts managed by the portfolio manager and the portfolio manager’s ownership of securities in the Fund.

Charles P. McQuaid, CFA

Lead manager or co-manager since inception in 2002.

President of the Investment Manager; associated with the Investment Manager or its predecessors as an investment professional since 1978; President of the Trust since 2003 and Trustee since 1992. Mr. McQuaid began his investment career in 1976 and earned a B.B.A. from the University of Massachusetts and an M.B.A. from the University of Chicago.

The Administrator

The Administrator is responsible for overseeing the administrative operations of the Fund, including the general supervision of the Fund’s operations, coordination of the Fund’s service providers, and the provision of office facilities and related clerical and administrative services. The Administrator pays a fee for the services of the Sub-Administrator.

The Fund pays the Administrator a fee for its services, plus certain out-of-pocket expenses. The fee is calculated as an annual percentage of the Trust’s aggregate average daily net assets and is paid monthly, as follows:

Annual Administration Fee,

as a % of Aggregate Average Daily Net Assets of the Trust

Up to $8 billion	0.050	%
$8 billion to $16 billion	0.040	%
$16 billion to $35 billion	0.030	%
$35 billion to $45 billion	0.025	%
$45 billion and over	0.015	%

The Distributor

Shares of the Fund are distributed by the Distributor, which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and wholly owned subsidiary of Ameriprise Financial. The Distributor and its affiliates may pay commissions, distribution and service fees and/or other compensation to entities, including Ameriprise Financial affiliates, for selling shares and providing services to investors.

The Transfer Agent

The Transfer Agent is a registered transfer agent and wholly owned subsidiary of Ameriprise Financial. The Transfer Agent is located at 225 Franklin Street, Boston, MA 02110, and its responsibilities include processing purchases, sales and exchanges, calculating and paying distributions, keeping shareholder records, preparing account statements and providing customer service (Shareholder Services). The Transfer Agent has engaged DST Systems, Inc. including its affiliate, Boston Financial Data Services, as the Funds’ sub-transfer agent to provide certain Shareholder Services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares; these intermediaries also may provide Shareholder Services. The Fund generally pays the Transfer Agent a per account fee for each account held directly with the Transfer Agent and reimburses the Transfer Agent for certain out-of-pocket expenses. In addition, the Fund reimburses payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and with the type of intermediary and the type of Shareholder Services provided. For more information about Shareholder Services Fees, see Choosing a Share Class – Selling Agent Compensation.

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Expense Reimbursement Arrangements

The Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that ordinary operating expenses (excluding distribution and service fees, interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies) do not exceed the annual rates of 0.25% of the Fund’s average daily net assets for Class R4, 0.27% for Class R5 and 0.22% for Class Y through November 8, 2013. This fee and expense arrangement may only be modified or amended with approval from all parties to such arrangement, including the Fund and the Investment Manager.

The effective expense ratio for the Fund, gross of the contractual waiver/reimbursement discussed above, will vary in connection with the changes to the Portfolio Funds and to the allocation of the Fund’s assets among the Portfolio Funds, which the Investment Manager may make to from time to time, as described above under Principal Investment Strategies.

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Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest

This section describes certain actual and potential conflicts of interest that arise from the financial services activities of Ameriprise Financial and its affiliates. Ameriprise Financial is a major financial services company, engaged in a broad range of financial activities beyond the mutual fund-related activities of the Investment Manager, including: insurance, broker-dealer (sales and trading), asset management and financial services. As a consequence of these activities, Ameriprise Financial or its affiliates may have interests arising from their other business lines that conflict with the interests of the Fund. These activities may also, from time to time, place certain investment constraints on the management of the Fund that might not otherwise arise.

As described in Management of the Fund – Primary Service Providers, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent are all affiliates of Ameriprise Financial. In addition to the services that they provide to the Fund, they also provide substantially similar services (for which they are compensated) to other clients and customers, including the Columbia Funds and Other Funds. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, Other Funds or other clients and customers.

Examples of activities that could lead to conflicts of interest and/or impose limitations that could affect the Fund include the following:

• the Investment Manager and other Ameriprise Financial affiliates may receive compensation and other benefits related to the management/administration of the Fund, Columbia Funds and Other Funds and the sale of their shares;

• there may be competition for limited investment opportunities that must be allocated among the Fund, Columbia Funds and Other Funds or other clients and customers of the Investment Manager that may have the same or similar investment objectives as the Fund;

• management of the Fund may diverge from Other Funds, Columbia Funds or other clients and customers of the Investment Manager or Ameriprise Financial affiliates, for example, advice given to the Fund may differ from, or conflict with, advice given to other funds or accounts;

• there may be regulatory or investment restrictions imposed on the investment activities of the Investment Manager arising from the activities or holdings of Columbia Funds, Other Funds or other clients or customers of the Investment Manager or Ameriprise Financial and its affiliates, for example, caps on the aggregate amount of certain types of investments that may be made by affiliated entities;

• Ameriprise Financial or its affiliates may have potentially conflicting relationships with companies and other entities in which the Fund invests; and

• there may be regulatory and other restrictions relating to the sharing of information between Ameriprise Financial and its affiliates, including the Investment Manager, for example, if an affiliated entity were in possession of non-public information, the Investment Manager might be prohibited by law from using that information in connection with the management of the Fund.

The Investment Manager and Ameriprise Financial have adopted various policies and procedures that are intended to identify, monitor and address conflicts of interest. However, there is no absolute assurance that these policies, procedures and disclosures will be effective.

Additional information about Ameriprise Financial and the types of conflicts of interest and other matters referenced above is set forth in the Investment Advisory and Other Services – Other Roles and Relationships of Ameriprise Financial and Affiliates – Certain Conflicts of Interest section of the SAI, which is identified by the icon. Investors in the Fund should carefully review these disclosures and consult with their financial advisor if they have any questions.

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Certain Legal Matters

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Fund is not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Fund or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Fund. Information regarding certain pending and settled legal proceedings may be found in the Fund’s shareholder reports and in the SAI. Additionally, Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the SEC on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the Columbia Funds generally share the same policies and procedures for investor services, as described below.

Funds Contact Information

Additional information about the Funds can be obtained at www.columbiamanagement.com,* by calling toll-free 800.345.6611, or by writing (regular mail) to Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081 or (express mail) Columbia Management Investment Services Corp., c/o Boston Financial, 30 Dan Road, Suite 8081, Canton, MA 02021-2809.

* The website references in this prospectus are intended to be inactive textual references and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals^TM

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” refer to the financial intermediaries that are authorized to sell shares of the Funds. Selling and/or servicing agents (collectively, selling agents) include broker-dealers and financial advisors as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisors, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Retirement Plans and Omnibus Retirement Plans

The term “retirement plan” refers to retirement plans created under sections 401(a), 401(k), 457 and 403(b) of the Internal Revenue Code of 1986, as amended (the Code), non-qualified deferred compensation plans governed by section 409A of the Code and similar plans but does not refer to individual retirement plans. The term “omnibus retirement plan” refers to a retirement plan that has a plan-level or omnibus account with the Transfer Agent.

Summary of Share Class Features

Each share class has its own investment eligibility criteria, cost structure and other features. You may not be eligible for every share class. If you purchase shares of a Fund through a retirement plan or other product or program offered by your selling agent, not all share classes of the Fund may be made available to you. When deciding which class of shares to buy, you should consider, among other things:

• The amount you plan to invest.

• How long you intend to remain invested in the Fund.

• The expenses for each share class.

• Whether you may be eligible for a reduction or waiver of sales charges when you buy or sell shares.

Each investor’s personal situation is different and you may wish to discuss with your selling agent which share classes are available to you and which share class is appropriate for you.

The following summarizes the primary features of Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares. Not all Funds offer every class of shares. Only Class R4, Class R5 and Class Y shares are offered by this prospectus. A Fund may offer other classes of shares in separate prospectuses. Although certain share classes are generally closed to new or existing investors, information relating to these share classes is included in the table below because certain qualifying purchase orders are permitted, as described below.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion  Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class A	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit and Conversion Features: None	5.75% maximum, declining to 0.00% on investments of $1 million or more	CDSC on certain investments of between $1 million and $50 million redeemed within 18 months of purchase, charged as follows: •   1.00% CDSC if redeemed within 12 months of purchase, and •   0.50% CDSC if redeemed more than 12, but less than 18, months of purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors(c) Investment Limit: Up to $49,999 Conversion Features: Converts to Class A shares eight years after purchase(d)	None	5.00% maximum, gradually declining to 0.00% after six years(d)	Distribution Fee: 0.50% Service Fee: 0.25%
Class C	Eligibility: Available to the general public for investment Minimum Initial Investment: $2,000 for most investors Investment Limit: Up to $999,999; none for omnibus retirement plans Conversion Features: None	None	1.00% on certain investments redeemed within one year of purchase	Distribution Fee: 0.75% Service Fee: 0.25%
Class I	Eligibility: Available only to other Funds (i.e., fund-of-fund investments) Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R	Eligibility: Available only to eligible retirement plans, health savings accounts and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class R4	Eligibility: Available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts Minimum Initial Investment, Investment Limit and Conversion Features: None	None	None	None
Class R5	Eligibility: Available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans(c) Minimum Initial Investment: None for omnibus retirement plans; $100,000 for combined underlying accounts of eligible registered investment advisers Investment Limit and Conversion Features: None	None	None	None
Class Y	Eligibility: Available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments; Investment Limits; and Conversion Features	Front-End Sales Charges(a)	Contingent Deferred Sales Charges (CDSCs)(a)	Maximum Distribution and/or Service (12b-1) Fees(b)
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; effective March 29, 2013, closed to (i) accounts of selling agents that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and (ii) omnibus retirement plans, subject to certain exceptions(c) Minimum Initial Investment: See Eligibility above Investment Limit and Conversion Features: None	None	None	None

^(a)  For more information on applicable sales charges, see Choosing a Share Class – Sales Charges and Commissions and for information about certain exceptions to these sales charges, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

^(b)  These are the maximum applicable distribution and/or shareholder service fees. Because these fees are paid out of Fund assets on an ongoing basis, over time these fees will increase the cost of your investment and may cost you more than paying other types of distribution and/or shareholder service fees. For more information on distribution and service fees, see Choosing a Share Class – Distribution and Service Fees.

^(c)  These share classes are closed, or will be closed, to new accounts generally or to new accounts of certain categories of investors, subject to certain conditions, as summarized below and described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors:

• Class B Shares. The Funds no longer accept investments from new or existing investors in Class B shares, except through reinvestment of dividend and/or capital gain distributions by existing Class B shareholders.

• Class R5 Shares. Shareholders with Class R5 accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

• Class Z Shares. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013.

^(d)  Timing of conversion and CDSC schedules will vary depending on the Fund and the date of your original purchase of Class B shares. For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class – Sales Charges and Commissions.

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents, and typically your financial advisor, for selling shares to you and for maintaining and servicing the shares held in your account with them. These charges, commissions and fees are intended to provide incentives for selling agents to provide these services. Depending on which share class you choose you will pay these charges either at the outset as a front-end sales charge, at the time you sell your shares as a CDSC and/or over time in the form of increased ongoing fees.

As described in more detail below, Class A shares have a front-end sales charge, which is deducted from your purchase price when you buy your shares, and results in a smaller dollar amount being invested in a fund than the purchase price you pay (unless you

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qualify for a waiver or reduction of the sales charge). The Fund’s other share classes do not have a front-end sales charge, so the full amount of your purchase is invested in those classes. Class A shares of the Fund have lower ongoing distribution (12b-1) and/or shareholder servicing fees than Class B, Class C and Class R shares of the Fund. Over time, Class B, Class C and Class R shares can incur distribution (12b-1) and shareholder servicing fees that are equal to or more than the front-end sales charge and the distribution (12b-1) and shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C and Class R shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Fund do not have distribution (12b-1) and/or shareholder servicing fees.

Whether the ultimate cost is higher for one class over another depends on the amount you invest, how long you hold your shares and whether you are eligible for reduced or waived sales charges. The differential between classes also will vary depending on the actual investment return for any given investment period. We encourage you to consult with a financial advisor who can help you with your investment decisions.

Class A Shares—Front-End Sales Charge

You’ll pay a front-end sales charge when you buy Class A shares, resulting in a smaller dollar amount being invested in a Fund than the purchase price you pay, unless you qualify for a waiver of the sales charge or you buy the shares through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges.

The Distributor receives the sales charge and re-allows (or pays) a portion of the sales charge to the selling agent through which you purchased the shares. The Distributor retains the balance of the sales charge. The Distributor retains the full sales charge you pay when you purchase shares of the Fund directly from the Fund (rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals^TM

Front-End Sales Charge Calculation

The table below presents the front-end sales charge as a percentage of both the offering price and the net amount invested.

• The net asset value (or NAV) per share is the price of a share calculated by the Fund every business day.

• The offering price per share is the NAV per share plus any front-end sales charge that applies.

The dollar amount of the sales charge is the difference between the offering price of the shares you buy (based on the applicable sales charge for the Fund) and the net asset value of those shares. To determine the front-end sales charge you will pay when you buy your shares, the Fund will add the amount of your investment to the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notify the Fund) and base the sales charge on the aggregate amount. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation. There is no initial sales charge on reinvested dividend or capital gain distributions.

The front-end sales charge you’ll pay on Class A shares:

• depends on the amount you’re investing (generally, the larger the investment, the smaller the percentage sales charge), and

• is based on the total amount of your purchase and the value of your account (and any other accounts eligible for aggregation of which you or your selling agent notifies the Fund).

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Class A Shares—Front-End Sales Charge—Breakpoint Schedule

Dollar amount of shares bought(a)	Sales charge as a % of the offering price(b)			Sales charge as a % of the net amount invested(b)			Amount retained by or paid to selling agents as a % of the offering price
$0 – $49,999		5.75	%		6.10	%		5.00	%
$50,000 – $99,999		4.50	%		4.71	%		3.75	%
$100,000 – $249,999		3.50	%		3.63	%		3.00	%
$250,000 – $499,999		2.50	%		2.56	%		2.15	%
$500,000 – $999,999		2.00	%		2.04	%		1.75	%
$1,000,000 or more		0.00	%		0.00	%		0.00	%(c)

^(a)  Purchase amounts and account values may be aggregated among all eligible Fund accounts for the purposes of this table. See Choosing a Share Class – Reductions/Waivers of Sales Charges for a discussion of account value aggregation.

^(b)  Because the offering price is calculated to two decimal places, the dollar amount of the sales charge as a percentage of the offering price and your net amount invested for any particular purchase of Fund shares may be higher or lower depending on whether downward or upward rounding was required during the calculation process. Purchase price includes the sales charge.

^(c)  For information regarding cumulative commissions paid to your selling agent when you buy $1 million or more of Class A shares of a Fund, see Class A Shares – Commissions below.

Class A Shares—CDSC

In some cases, you’ll pay a CDSC if you sell Class A shares that you purchased without an initial sales charge.

• If you purchased Class A shares without an initial sales charge because your accounts aggregated between $1 million and $50 million at the time of purchase, you will incur a CDSC if you redeem those shares within 18 months of purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months of purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months of purchase.

• Subsequent Class A share purchases that bring your aggregate account value to $1 million or more (but less than $50 million) will also be subject to a CDSC if you redeem them within the time periods noted above.

FUNDamentals^TM

Contingent Deferred Sales Charge

A contingent deferred sales charge or CDSC is a sales charge applied at the time you sell your shares, unlike a front-end sales charge that is applied at the time of purchase. A CDSC varies based on the length of time that you have held your shares. A CDSC is applied to the NAV at the time of your purchase or sale, whichever is lower, and will not be applied to any shares you receive through reinvested distributions or any amount that represents appreciation in the value of your shares. For purposes of calculating a CDSC, the start of the holding period is generally the first day of the month in which your purchase was made.

When you place an order to sell shares of a class that has a CDSC, the Fund will first redeem any shares that aren’t subject to a CDSC, followed by those you have held the longest. This means that if a CDSC is imposed, you cannot designate the individual shares being redeemed for U.S. federal income tax purposes. You should consult your tax advisor about the tax consequences of investing in the Fund. In certain circumstances, the CDSC may not apply. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details.

Class A Shares—Commissions

The Distributor may pay your selling agent an up-front commission when you buy Class A shares. The Distributor generally funds the commission through the applicable sales charge paid by you. For more information, see Class A Shares – Front-End Sales Charge – Breakpoint Schedule, Amount retained by or paid to selling agents as a % of the offering price.

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The Distributor may also pay your selling agent a cumulative commission when you buy $1 million or more of Class A shares, according to the following schedule:

Class A Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$1 million – $2,999,999		1.00	%
$3 million – $49,999,999		0.50	%
$50 million or more		0.25	%

Class B Shares—Sales Charges

The Funds no longer accept new investments in Class B shares, except for certain limited transactions as described in more detail under Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class B Shares (Closed).

You don’t pay a front-end sales charge when you buy Class B shares, but you may pay a CDSC when you sell Class B shares.

Class B Shares—CDSC

You’ll pay a CDSC if you sell Class B shares unless you qualify for a waiver of the CDSC or the shares you’re selling were bought through reinvested distributions. See Choosing a Share Class – Reductions/Waivers of Sales Charges for details. The CDSC you pay on Class B shares depends on how long you’ve held your shares and generally declines each year until there is no sales charge, as follows:

Class B Shares—CDSC Schedule for the Funds

Number of Years Class B Shares Held	Applicable CDSC*
One	5.00%
Two	4.00%
Three	3.00%
Four	3.00%
Five	2.00%
Six	1.00%
Seven	none
Eight	none
Nine	Conversion to Class A Shares

* Because of rounding in the calculation, the actual CDSC you pay may be more or less than the CDSC calculated using these percentages.

Class B Shares—Commissions

The Distributor paid an up-front commission directly to your selling agent when you bought the Class B shares (a portion of this commission may have been paid to your financial advisor). This up-front commission was up to 4.00% of the net asset value per share. The Distributor continues to seek to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan and any applicable CDSC paid when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Class B Shares—Conversion to Class A Shares

Class B shares of the Funds automatically convert to Class A shares after you’ve owned the shares for eight years. For details and related information about how the Funds’ Class B shares convert to Class A shares, see Appendix S to the SAI.

Class C Shares—Front-End Sales Charge

You don’t pay a front-end sales charge when you buy Class C shares. Although Class C shares do not have a front-end sales charge such that the full amount of your purchase price is invested in a Fund, over time Class C shares can incur distribution (12b-1) and/or shareholder servicing fees that are equal to or more than the front-end sales charge and distribution (12b-1) and/or shareholder servicing fees you would pay for Class A shares. Thus, although the full amount of your purchase of Class C shares is invested in a Fund, any positive investment return on this money may be partially or fully offset by the expected higher annual expenses of Class C shares.

Class C Shares—CDSC

You’ll pay a CDSC of 1.00% if you redeem Class C shares within 12 months of buying them unless you qualify for a waiver of the CDSC or the shares you’re selling were purchased through reinvested distributions. For more information, see Choosing a Share Class – Reductions/Waivers of Sales Charges. Redemptions of Class C shares are not subject to a CDSC if redeemed after 12 months.

Class C Shares—Commissions

Although there is no front-end sales charge when you buy Class C shares, the Distributor pays an up-front commission directly to your selling agent of up to 1.00% of the net asset value per share when you buy Class C shares (a portion of this commission may be paid to your financial advisor). The Distributor seeks to recover this commission through distribution fees of 0.75% it receives under the Fund’s distribution and/or service plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class – Distribution and Service Fees.

Class R Shares—Sales Charges and Commissions

You don’t pay a front-end sales charge when you buy Class R shares of the Fund or a CDSC when you sell Class R shares of the Fund. The Distributor pays an up-front commission directly to your selling agent when you buy Class R shares (a portion of this commission may be paid to your financial advisor), according to the following schedule:

Class R Shares—Commission Schedule (Paid by the Distributor to Selling Agents)

Purchase Amount	Commission Level (as a % of net asset value per share)
$0 – $49,999,999		0.50	%
$50 million or more		0.25	%

The Distributor seeks to recover this commission through distribution fees of 0.50% it receives under the Fund’s distribution plan. For more information, see Choosing a Share Class – Distribution and Service Fees.

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Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

There are two ways in which you may be able to reduce the front-end sales charge that you may pay when you buy Class A shares of a Fund. These types of sales charge reductions are also referred to as breakpoint discounts.

First, through the right of accumulation (ROA), you may combine the value of eligible accounts maintained by you and members of your immediate family to reach a breakpoint discount level and apply a lower sales charge to your purchase. To calculate the combined value of your Fund accounts in the particular class of shares, the Fund will use the current public offering price per share. For purposes of obtaining a breakpoint discount through ROA, you may aggregate your or your immediate family members’ ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for ROA purposes.

Second, by making a statement of intent to purchase additional shares (commonly referred to as a letter of intent (LOI)), you may pay a lower sales charge on all purchases (including existing ROA purchases) of Class A shares made within 13 months of the date of your LOI. Your LOI must state the aggregate amount of purchases you intend to make in that 13-month period, which must be at least $50,000 (or $100,000 for Funds with breakpoint discounts beginning at $100,000). The required form of LOI may vary by selling agent, so please contact them directly for more information. Five percent of the purchase commitment amount will be placed in escrow. At the end of the 13-month period, the shares will be released from escrow, provided that you have invested the commitment amount. If you do not invest the commitment amount by the end of the 13 months, the remaining amount of the unpaid sales charge will be redeemed from the escrowed shares and the remaining balance released from escrow. To calculate the total value of the purchases you’ve made under an LOI, the Fund will use the historic cost (i.e., dollars invested) of the shares held in each eligible account. For purposes of making an LOI to purchase additional shares, you may aggregate your ownership of different classes of shares, except for Class I, Class K, Class R, Class R4, Class R5 and Class Y shares of the Funds and direct purchases of Columbia Money Market Fund and Columbia Government Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund and Columbia Government Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

You must request the reduced sales charge (whether through ROA or an LOI) when you buy shares. If you do not complete and file an LOI, or do not request the reduced sales charge at the time of purchase, you will not be eligible for the reduced sales charge. To obtain a breakpoint discount, you must notify your selling agent in writing at the time you buy your shares of each eligible account maintained by you and members of your immediate family, including accounts maintained through different selling agents. You and your selling agent are responsible for ensuring that you receive discounts for which you are eligible. The Fund is not responsible for a selling agent’s failure to apply the eligible discount to your account. You may be asked by your selling agent for account statements or other records to verify your discount eligibility, including, when applicable, records for accounts opened with a different selling agent and records of accounts established by members of your immediate family.

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FUNDamentals^TM

Your “Immediate Family” and Account Value Aggregation

For purposes of obtaining a breakpoint discount for Class A shares, the value of your account will be deemed to include the value of all applicable shares in eligible Fund accounts that are held by you and your “immediate family,” which includes your spouse, domestic partner, parent, step-parent, legal guardian, child, step-child, father-in-law and mother-in-law, provided that you and your immediate family members share the same mailing address. Any Fund accounts linked together for account value aggregation purposes as of the close of business on September 3, 2010 will be permitted to remain linked together. Group plan accounts are valued at the plan level.

Eligible Accounts

The following accounts are eligible for account value aggregation as described above, provided that they are invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W or Class Z shares of a Fund: individual or joint accounts; Roth and traditional Individual Retirement Accounts (IRAs); Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs); Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors Act (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child; revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor; accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation; qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and investments in wrap accounts.

The following accounts are not eligible for account value aggregation as described above: accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts); investments in 529 plans, donor advised funds, variable annuities, variable insurance products or managed separate accounts; charitable and irrevocable trust accounts; accounts holding shares of money market funds that used the Columbia brand before May 1, 2010; and accounts invested in Class I, Class K, Class R, Class R4, Class R5 or Class Y shares of a Fund.

Front-End Sales Charge Waivers

The Distributor may waive front-end sales charges on purchases of Class A shares of the Funds by certain categories of investors, including Board members, certain employees of selling agents, Fund portfolio managers and certain retirement and employee benefit plans. The Distributor may waive front-end sales charges on (i) purchases (including exchanges) of Class A shares in accounts of selling agents that have entered into agreements with the Distributor to offer Fund shares to self-directed investment brokerage accounts that may or may not charge a transaction fee to customers and (ii) exchanges of Class Z shares of a Fund for Class A shares of the Fund. For a more complete description of categories of investors who may purchase Class A shares of the Funds at NAV, without payment of any front-end sales charge that would otherwise apply, see Appendix S to the SAI. In addition, certain types of purchases of Class A shares may be made at NAV. For a description of these eligible transactions, see Appendix S to the SAI.

CDSC Waivers

You may be able to avoid an otherwise applicable CDSC when you sell Class A, Class B or Class C shares of the Fund. This could happen because of the way in which you originally invested in the Fund, because of your relationship with the Funds or for other reasons. For example, the CDSC will be waived on redemptions of shares in the event of the shareholder’s death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70 ¹/₂; and by certain other

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investors and in certain other types of transactions. For a more complete description of the available waivers of the CDSC on redemptions of Class A, Class B and Class C shares, see Appendix S to the SAI.

Repurchases

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a redemption of any Class A, Class B or Class C shares of a Fund (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the redemption proceeds. Any CDSC paid upon redemption of your Class A, Class B or Class C shares of a Fund will not be reimbursed.

To be eligible for the reinstatement privilege, the purchase must be made into an account for the same owner, but does not need to be into the same Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request from you or your selling agent within 90 days after the shares are redeemed and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in “good form”. The repurchased shares will be deemed to have the original purchase date for purposes of applying the CDSC (if any) to subsequent redemptions. Systematic withdrawals and purchases are excluded from this policy.

Restrictions and Changes in Terms and Conditions

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms and conditions at any time. Unless you provide your selling agent with information in writing about all of the factors that may count toward a waiver of a sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your selling agent provide this information to the Fund when placing your purchase order. Please see Appendix S of the SAI for more information about the sales charge reductions and waivers.

Distribution and Service Fees

The Board has approved, and the Funds have adopted, distribution and/or shareholder service plans which set the distribution and/or service fees that are periodically deducted from the Fund’s assets. These fees are calculated daily, may vary by share class and are intended to compensate the Distributor and/or eligible selling agents for selling Fund shares and directly or indirectly providing services to shareholders. Because the fees are paid out of the Fund’s assets on an ongoing basis, they will increase the cost of your investment over time.

The table below shows the maximum annual distribution and/or service fees (as an annual % of average daily net assets) and the combined amount of such fees applicable to each share class:

	Distribution Fee			Service Fee			Combined Total
Class A		None			0.25	%		0.25	%
Class B		0.50	%		0.25	%		0.75	%
Class C		0.75	%		0.25	%		1.00	%
Class I		None			None			None
Class R		0.50	%		None			0.50	%
Class R4		None			None			None
Class R5		None			None			None
Class Y		None			None			None
Class Z		None			None			None

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The distribution and/or shareholder service fees for Class A, Class B, Class C and Class R shares, as applicable, are subject to the requirements of Rule 12b-1 under the 1940 Act. The Distributor may retain these fees otherwise payable to selling agents if the amounts due are below an amount determined by the Distributor in its sole discretion.

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or selling agent, distribution and service fees may be retained by the Distributor as payment or reimbursement for incurring certain distribution and shareholder service related expenses.

Over time, these distribution and/or shareholder service fees will reduce the return on your investment and may cost you more than paying other types of sales charges. The Fund will pay these fees to the Distributor and/or to eligible selling agents for as long as the distribution and/or shareholder servicing plans continue in effect, which is expected to be indefinitely. The Fund may reduce or discontinue payments at any time. Your selling agent may also charge you other additional fees for providing services to your account, which may be different from those described here.

Selling Agent Compensation

The Distributor, the Investment Manager and their affiliates make payments, from their own resources, to selling agents, including other Ameriprise Financial affiliates, for marketing/sales support services relating to the Funds (Marketing Support Payments). Such payments are generally based upon one or more of the following factors: average net assets of the Funds sold by the Distributor attributable to that selling agent, gross sales of the Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment. While the financial arrangements may vary for each selling agent, Marketing Support Payments to any one selling agent are generally between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Fund attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Funds attributable to the selling agent. The Distributor and the Investment Manager may make payments in larger amounts or on a basis other than those described above when dealing with certain selling agents, including certain affiliates of Bank of America Corporation (Bank of America). Such increased payments may enable such selling agents to offset credits that they may provide to customers. The Distributor, the Investment Manager and their affiliates do not make Marketing Support Payments with respect to Class Y shares of the Columbia Acorn Funds.

In addition, the Transfer Agent has certain arrangements in place to compensate selling agents, including other Ameriprise Financial affiliates, that hold Fund shares through omnibus accounts, including omnibus retirement plans, for services that they provide to beneficial shareholders (Shareholder Services). Shareholder Services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and providing customer service. Payments for Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of the Fund’s shares. Generally, through April 30, 2013, each Columbia Acorn Fund pays (i) 0.115% of the average aggregate value of the Fund’s shares attributable to selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other selling agents not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not pay any Shareholder Services fees. The amounts in excess of those reimbursed by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates. The Transfer Agent does not pay selling agents for Shareholder Services and the Fund does not pay the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares.

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In addition to the payments described above, the Distributor, the Investment Manager and their affiliates may make other payments or allow promotional incentives to broker-dealers to the extent permitted by SEC and Financial Industry Regulatory Authority (FINRA) rules and by other applicable laws and regulations.

Amounts paid by the Distributor, the Investment Manager and their affiliates are paid out of their own resources and do not increase the amount paid by you or the Fund. You can find further details in the SAI about the payments made by the Distributor, the Investment Manager and their affiliates, as well as a list of the selling agents, including Ameriprise Financial affiliates, to which the Distributor and the Investment Manager have agreed to make Marketing Support Payments and Shareholder Services fees.

Your selling agent may charge you fees and commissions in addition to those described in this prospectus. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial advisors may have a financial incentive for recommending the Fund or a particular share class over others.

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Buying, Selling and Exchanging Shares

Share Price Determination

The price you pay or receive when you buy, sell or exchange shares is the Fund’s next determined net asset value (or NAV) per share for a given share class. The Fund calculates the NAV per share for each class of shares of the Fund at the end of each business day.

The value of the Fund’s shares is based on the total market value of all of the securities and other assets that it holds as of a specified time.

FUNDamentals^TM

NAV Calculation

Each of the Fund’s share classes calculates its NAV as follows:

NAV =	(Value of assets of the share class) —(Liabilities of the share class)
	Number of outstanding shares of the class

FUNDamentals^TM

Business Days

A business day is any day that the New York Stock Exchange (NYSE) is open. A business day ends at the close of regular trading on the NYSE, usually at 4:00 p.m. Eastern time. If the NYSE closes early, the business day ends as of the time the NYSE closes. On holidays and other days when the NYSE is closed, the Fund's NAV is not calculated and the Fund does not accept buy or sell orders. However, the value of the Fund's assets may still be affected on such days to the extent that the Fund holds foreign securities that trade on days that foreign securities markets are open.

Equity securities are valued primarily on the basis of market quotations reported on stock exchanges and other securities markets around the world. Certain equity securities, debt securities and other assets are valued differently. For instance, short-term investments maturing in 60 days or less are valued primarily using the amortized cost method and those maturing in excess of 60 days are valued at the readily available market price, if available. For a Fund organized as a fund-of-funds, its investments in other funds are valued at their NAVs. Market quotations are obtained from outside pricing services approved and monitored pursuant to a policy approved by the Fund’s Board.

If a market price isn’t readily available or is deemed not to reflect market value, the Fund will determine the price of the security held by the Fund based on a determination of the security’s fair value pursuant to a policy approved by the Fund’s Board. In addition, the Fund may use fair valuation to price securities that trade on a foreign exchange when a significant event has occurred after the foreign exchange closes but before the time at which the Fund’s share price is calculated. Foreign exchanges typically close before the time at which Fund share prices are calculated, and may be closed altogether on some days when the Fund is open. Such significant events affecting a foreign security may include, but are not limited to: (1) corporate actions, earnings announcements, litigation or other events impacting a single issuer; (2) governmental action that affects securities in one sector or country; (3) natural disasters or armed conflicts affecting a country or region; or (4) significant domestic or foreign market fluctuations. The Fund uses various criteria, including an evaluation of U.S. market moves after the close of foreign markets, in determining whether a foreign security’s market price is readily available and reflective of market value and, if not, the fair value of the security. In particular, the Fund evaluates and under certain circumstances may adjust the closing market price of foreign securities. The Fund has retained one or more independent fair valuation pricing services to assist in this fair valuation process for

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foreign securities.

Fair valuation may have the effect of reducing stale pricing arbitrage opportunities presented by the pricing of Fund shares. However, when the Fund uses fair valuation to price securities, it may value those securities higher or lower than another fund would have priced the security. Also, the use of fair valuation may cause the Fund’s performance to diverge to a greater degree from the performance of various benchmarks used to compare the Fund’s performance because benchmarks generally do not use fair valuation techniques. Because of the judgment involved in fair valuation decisions, there can be no assurance that the value ascribed to a particular security is accurate. International markets are sometimes open on days when U.S. markets are closed, which means that the value of foreign securities owned by the Fund could change on days when Fund shares cannot be purchased or sold.

Transaction Rules and Policies

The Fund, the Distributor or the Transfer Agent may refuse any order to buy or exchange shares. If this happens, the Fund will return any money it received, but no interest will be paid on that money.

Order Processing

Orders to buy, sell or exchange Fund shares are processed on business days. Depending upon the class of shares, orders can be made by mail, by telephone or online. Orders received in “good form” by the Transfer Agent or your selling agent before the end of a business day are priced at the NAV per share of the Fund’s applicable share class on that day.

Orders received after the end of a business day will receive the next business day’s NAV per share. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery. The market value of the Fund’s investments may change between the time you submit your order and the time the Fund next calculates its NAV per share. The business day that applies to your order is also called the trade date.

“Good Form”

An order is in “good form” if the Transfer Agent or your selling agent has all of the information and documentation it deems necessary to effect your order. For example, when you sell shares by letter of instruction, “good form” means that your letter has (i) complete instructions and the signatures of all account owners, (ii) a Medallion Signature Guarantee (as described below) for amounts greater than $100,000 and (iii) any other required documents completed and attached. For the documents required for sales by corporations, agents, fiduciaries, surviving joint owners and other legal entities, call 800.345.6611.

Medallion Signature Guarantees

A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. The selling agent providing the Medallion Signature Guarantee is financially liable for the transaction if the signature is a forgery.

A Medallion Signature Guarantee is required if:

• The amount is greater than $100,000.

• You want your check made payable to someone other than the registered account owner(s).

• Your address of record has changed within the last 30 days.

• You want the check mailed to an address other than the address of record.

• You want the proceeds sent to a bank account not on file.

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• You are the beneficiary of the account and the account owner is deceased (additional documents may be required).

Customer Identification Program

Federal law requires the Fund to obtain and record specific personal information to verify your identity when you open an account. This information may include your name, address, date of birth (for individuals) and taxpayer or other government issued identification (e.g., social security number (SSN) or other taxpayer identification number (TIN)). If you fail to provide the requested information, the Fund may need to delay the date of your purchase or may be unable to open your account, which may result in a return of your investment monies. In addition, if the Fund is unable to verify your identity after your account is open, the Fund reserves the right to close your account or take other steps as deemed reasonable. The Fund will not be liable for any loss resulting from any purchase delay, application rejection or account closure due to a failure to provide proper identifying information.

Information Sharing Agreements

As required by Rule 22c-2 under the 1940 Act, the Funds or certain of their service providers will enter into information sharing agreements with selling agents, including participating life insurance companies and selling agents that sponsor or offer retirement plans through which shares of the Funds are made available for purchase. Pursuant to Rule 22c-2, selling agents are required, upon request, to: (i) provide shareholder account and transaction information and (ii) execute instructions from the Fund to restrict or prohibit further purchases of Fund shares by shareholders who have been identified by the Fund as having engaged in transactions that violate the Fund’s excessive trading policies and procedures.

Excessive Trading Practices Policy

Right to Reject or Restrict Share Transaction Orders – The Fund is intended for investors with long-term investment purposes and is not intended as a vehicle for frequent trading activity (market timing) that is excessive. Investors should transact in Fund shares primarily for investment purposes. The Board has adopted excessive trading policies and procedures that are designed to deter excessive trading by investors (the Excessive Trading Policies and Procedures). The Fund discourages and does not accommodate excessive trading.

The Fund reserves the right to reject, without any prior notice, any buy or exchange order for any reason, and will not be liable for any loss resulting from rejected orders. For example, the Fund may in its sole discretion restrict or reject a buy or exchange order even if the transaction is not subject to the specific exchange limitation described below if the Fund or its agents determine that accepting the order could interfere with efficient management of the Fund’s portfolio or is otherwise contrary to the Fund’s best interests. The Excessive Trading Policies and Procedures apply equally to buy or exchange transactions communicated directly to the Transfer Agent and to those received by selling agents.

Specific Buying and Exchanging Limitations – If a Fund detects that an investor has made two “material round trips” in any 28-day period, it will generally reject the investor’s future buy orders, including exchange buy orders, involving any Fund.

For these purposes, a “round trip” is a purchase or exchange into the Fund followed by a sale or exchange out of the Fund, or a sale or exchange out of the Fund followed by a purchase or exchange into the Fund. A “material” round trip is one that is deemed by the Fund to be material in terms of its amount or its potential detrimental impact on the Fund. Independent of this limit, the Fund may, in its sole discretion, reject future buy orders by any person, group or account that appears to have engaged in any type of excessive trading activity.

These limits generally do not apply to automated transactions or transactions by registered investment companies that invest in the Fund using a “fund-of-funds” structure. These limits do not apply to payroll deduction contributions by retirement plan participants, transactions initiated by a retirement plan sponsor or certain other retirement plan transactions consisting of rollover transactions, loan repayments and disbursements, and required minimum distribution redemptions. They may be modified or

44

rescinded for accounts held by certain retirement plans to conform to plan limits, for considerations relating to the Employee Retirement Income Security Act of 1974 or regulations of the Department of Labor, and for certain asset allocation or wrap programs. Accounts known to be under common ownership or control generally will be counted together, but accounts maintained or managed by a common intermediary generally will not be considered to be under common ownership or control. The Fund retains the right to modify these restrictions at any time without prior notice to shareholders. In addition, the Fund may, in its sole discretion, reinstate trading privileges that have been revoked under the Fund’s excessive trading policies.

Limitations on the Ability to Detect and Prevent Excessive Trading Practices – The Fund takes various steps designed to detect and prevent excessive trading, including daily review of available shareholder transaction information. However, the Fund receives buy, sell and exchange orders through selling agents, and cannot always know of or reasonably detect excessive trading that may be facilitated by selling agents or by the use of the omnibus account arrangements they offer. Omnibus account arrangements are common forms of holding shares of mutual funds, particularly among certain selling agents such as broker-dealers, retirement plans and variable insurance products. These arrangements often permit selling agents to aggregate their clients’ transactions and accounts, and in these circumstances, the identity of the shareholders is often not known to the Fund.

Some selling agents apply their own restrictions or policies to underlying investor accounts, which may be more or less restrictive than those described here. This may impact the Fund’s ability to curtail excessive trading, even where it is identified. For these and other reasons, it is possible that excessive trading may occur despite the Fund’s efforts to detect and prevent it.

Although these restrictions and policies involve judgments that are inherently subjective and may involve some selectivity in their application, the Fund seeks to act in a manner that it believes is consistent with the best interests of shareholders in making any such judgments.

Risks of Excessive Trading – Excessive trading creates certain risks to the Fund’s long-term shareholders and may create the following adverse effects:

• negative impact on the Fund’s performance;

• potential dilution of the value of the Fund’s shares;

• interference with the efficient management of the Fund’s portfolio, such as the need to maintain undesirably large cash positions, the need to use its line of credit or the need to buy or sell securities it otherwise would not have bought or sold;

• losses on the sale of investments resulting from the need to sell securities at less favorable prices;

• increased taxable gains to the Fund’s remaining shareholders resulting from the need to sell securities to meet sell orders; and

• increased brokerage and administrative costs.

To the extent that the Fund invests significantly in foreign securities traded on markets that close before the Fund’s valuation time, it may be particularly susceptible to dilution as a result of excessive trading. Because events may occur after the close of foreign markets and before the Fund’s valuation time that influence the value of foreign securities, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of foreign securities as of the Fund’s valuation time. This is often referred to as price arbitrage. The Fund has adopted procedures designed to adjust closing market prices of foreign securities under certain circumstances to reflect what the Fund believes to be the fair value of those securities as of its valuation time. To the extent the adjustments don’t work fully, investors engaging in price arbitrage may cause dilution in the value of the Fund’s shares held by other shareholders.

The Columbia Acorn Funds invest significantly in thinly traded securities of small-capitalization companies. Because these securities are often traded infrequently, investors may seek to trade Fund shares in an effort to benefit from their understanding of the value of these securities. This is also a type of price arbitrage. Any such frequent trading strategies may interfere with efficient management of the Fund’s portfolio to a greater degree than would be the case for mutual funds that invest in highly liquid securities, in part because the Fund may have difficulty selling those portfolio securities at advantageous times or prices to satisfy

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large and/or frequent sell orders. Any successful price arbitrage may also cause dilution in the value of Fund shares held by other shareholders.

Opening an Account and Placing Orders

We encourage you to consult with a financial advisor who can help you with your investment decisions and who can help you open an account. Once you have an account, you can buy, sell and exchange shares by contacting your financial advisor who will send your order to the Transfer Agent or your selling agent. As described below, once you have an account you can also communicate your orders directly to the Transfer Agent by mail, by telephone or online.

The Funds are generally available directly and through broker-dealers, banks and other selling agents or institutions, and through certain qualified and non-qualified plans, wrap fee products or other investment products sponsored by selling agents. You may exchange or sell shares through your selling agent. If you maintain your account directly with your selling agent, you must contact that agent to process your transaction.

Not all selling agents offer the Funds and certain selling agents that offer the Funds may not offer all Funds on all investment platforms or programs. Please consult with your financial advisor to determine the availability of the Funds. If you set up an account at a selling agent that does not have, and is unable to obtain, a selling agreement with the Distributor, you will not be able to transfer Fund holdings to that account. In that event, you must either maintain your Fund holdings with your current selling agent, find another selling agent with a selling agreement, or sell your Fund shares, paying any applicable CDSC. Please be aware that transactions in taxable accounts are taxable events and may result in income tax liability.

Selling agents that offer the Funds may charge you additional fees for the services they provide and they may have different policies that are not described in this prospectus. Some policy differences may include different minimum investment amounts, exchange privileges, Fund choices and cutoff times for investments. Additionally, recordkeeping, transaction processing and payments of distributions relating to your account may be performed by the selling agents through which your shares of the Fund are held. Since the Fund (and its service providers) may not have a record of your account transactions, you should always contact the financial advisor employed by the selling agent through which you purchased or at which you maintain your shares of the Fund to make changes to your account or to give instructions concerning your account, or to obtain information about your account. The Fund and its service providers, including the Distributor and the Transfer Agent, are not responsible for the failure of one of these selling agents to carry out its obligations to its customers.

The Fund may engage selling agents to receive purchase orders and exchange (and sale) orders on its behalf. Accounts established directly with the Fund will be serviced by the Transfer Agent. The Funds, the Transfer Agent and the Distributor do not provide investment advice.

Accounts Established Directly with the Fund

You or the financial advisor through which you buy shares may establish an account with the Fund. To do so, complete a Fund account application with your financial advisor or investment professional, and mail the account application to the Transfer Agent. Account applications may be obtained at www.columbiamanagement.com or may be requested by calling 800.345.6611. Make your check payable to the Fund. You will be assessed a $15 fee for any checks rejected by your financial institution due to insufficient funds or other reasons. The Funds do not accept cash, credit card convenience checks, money orders, traveler’s checks, starter checks, third or fourth party checks, or other cash equivalents.

Mail your check and completed application to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. You may also use these addresses to request an exchange or redemption of Fund shares. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O.

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Box provided for regular mail delivery.

You will be sent a statement confirming your purchase and any subsequent transactions in your account. You will also be sent quarterly and annual statements detailing your transactions in the Fund and the other Funds you own under the same account number. Duplicate quarterly account statements for the current year and duplicate annual statements for the most recent prior calendar year will be sent to you free of charge. Copies of year-end statements for prior years are available for a fee. Please contact the Transfer Agent for more information.

Written Transactions

Once you have an account, you can communicate written buy, sell or exchange orders to the Transfer Agent at its address that can be found at the beginning of the section Choosing a Share Class. When a written order to buy, sell or exchange shares is sent to the Transfer Agent, the share price used to fill the order is the next price calculated by the Fund after the Transfer Agent receives the order at its transaction processing center in Canton, Massachusetts, not the P.O. Box provided for regular mail delivery.

Include in your letter: your name; the name of the Fund(s); your account number; the class of shares to be exchanged or sold; your SSN or other TIN; the dollar amount or number of shares you want to exchange or sell; specific instructions regarding delivery or exchange destination; signature(s) of registered account owner(s); and any special documents the Transfer Agent may require in order to process your order.

Corporate, trust or partnership accounts may need to send additional documents. Payment will be mailed to the address of record and made payable to the names listed on the account, unless your request specifies differently and is signed by all owners.

Telephone Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may place orders to buy, sell or exchange shares by telephone. To place orders by telephone, call 800.422.3737. Have your account number and SSN or TIN available when calling.

You can sell via the telephone, by electronic funds transfer or by check to the address of record, up to and including an aggregate of $100,000 of shares per day, per Fund account, if you qualify for telephone orders. Wire redemptions requested via the telephone are subject to a maximum of $3 million of shares per day, per Fund. You can buy up to and including $100,000 of shares per day, per Fund account through your bank account as an ACH transaction via the telephone if you qualify for telephone orders.

Telephone orders may not be as secure as written orders. The Fund will take reasonable steps to confirm that telephone instructions are genuine. For example, we require proof of your identification before we will act on instructions received by telephone and may record telephone conversations. However, the Fund and its agents will not be responsible for any losses, costs or expenses resulting from an unauthorized telephone instruction when reasonable steps have been taken to confirm that telephone instructions are genuine. Telephone orders may be difficult to complete during periods of significant economic or market change or business interruption.

Online Transactions

For Class A, Class B, Class C, Class R, Class Y and Class Z shares, once you have an account, you may contact the Transfer Agent at 800.345.6611 for more information on account trading restrictions and the special sign-up procedures required for online transactions.

The Transfer Agent has procedures in place to authenticate electronic orders you deliver through the internet. You will be required to accept the terms of an online agreement and to establish and utilize a password in order to access online account services. You can sell up to and including an aggregate of $100,000 of shares per day, per Fund account through the internet if you qualify for

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internet orders.

Wire Transactions

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by wiring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737.

You must set up this feature prior to your request unless you are submitting your request in writing with a Medallion Signature Guarantee. The Transfer Agent charges a fee for shares sold by Fedwire. The Transfer Agent may waive the fee for certain accounts. In the case of a redemption, the receiving bank may charge an additional fee. The minimum amount that can be redeemed by wire is $500. The maximum amount that can be redeemed over the telephone is $3 million per day, per Fund account.

Electronic Funds Transfer

You may buy (or redeem) Class A, Class B (redemptions only), Class C, Class Y and Class Z shares of a Fund by electronically transferring money from (or to) your bank account to (or from) your Fund account by calling the Transfer Agent at 800.422.3737. An electronic funds transfer may take up to three business days to settle and be considered in “good form.” You must set up this feature by contacting the Transfer Agent prior to your request to obtain any necessary forms.

Important: Payments sent by electronic fund transfers, a bank authorization, or check that are not guaranteed may take up to 10 or more days to clear. If you request a redemption before the purchase funds clear, this may cause your redemption request to fail to process if the requested amount includes unguaranteed funds. If you purchased your shares by check or from your bank account as an ACH transaction, the Fund may hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

Buying Shares

Eligible Investors

Class A and Class C Shares

Class A and Class C shares are available to the general public for investment. Once you have opened an account, you can buy Class A and Class C shares in a lump sum, through our Systematic Investment Plan, by dividend diversification, by wire or by electronic funds transfer.

Class B Shares (Closed)

The Funds no longer accept investments from new or existing investors in Class B shares. Additional Class B shares of the Fund will be issued only in connection with the reinvestment of dividends or capital gains distributions in Class B shares of the Fund by the Fund’s existing Class B shareholders (Qualifying Transactions).

Any initial purchase orders for the Fund’s Class B shares will be rejected (other than through a Qualifying Transaction that is an exchange transaction).

Unless contrary instructions are received in advance by the Fund, any purchase orders (except those submitted by a selling agent through the National Securities Clearing Corporation (NSCC) as described in more detail below) that are orders for additional Class B shares of the Fund received from existing investors in Class B shares, including orders made through an active systematic investment plan, will automatically be invested in Class A shares of the Fund, without regard to the normal minimum initial investment requirement for Class A shares, but subject to the front-end sales charge that generally applies to Class A shares. See Choosing a Share Class – Sales Charges and Commissions – Class A Shares – Front-End Sales Charge for additional information. Your

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selling agent may have different policies not described here, including a policy to reject purchase orders for a Fund’s Class B shares or to automatically invest the purchase amount in a money market Fund. Please consult your selling agent to understand their policy.

Additional purchase orders for a Fund’s Class B shares by an existing Class B shareholder, submitted by such shareholder’s selling agent through the NSCC, will be rejected due to operational limitations of the NSCC. Investors should consult their selling agent if they wish to invest in the Fund by purchasing a share class of the Fund other than Class B shares.

Dividend and/or capital gain distributions from Class B shares of a Fund will not be automatically invested in Class B shares of another Fund. Unless contrary instructions are received in advance of the date of declaration, such dividend and/or capital gain distributions from Class B shares of a Fund will be reinvested in Class B shares of the same Fund that is making the distribution.

Class I Shares

Class I shares are available only to the Funds (i.e., fund-of-fund investments).

Class R Shares

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, in the sole discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Class R4 Shares

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Class R5 Shares

Class R5 shares are available only to (i) certain registered investment advisers that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements and (ii) omnibus retirement plans. Prior to November 8, 2012, Class R5 shares were closed to new investors and new accounts, subject to certain exceptions. Existing shareholders who do not satisfy the new eligibility requirements for investment in Class R5 may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in accounts opened and funded prior to November 8, 2012; provided, however, that investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program.

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Class Y Shares

Class Y shares are available only to (i) omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account (without a minimum initial investment amount) and (ii) omnibus retirement plans with plan assets of less than $10 million as of the date of funding the Fund account, provided that such plans invest $500,000 or more in Class Y shares of the Fund. As with other minimum initial investment requirements, the Distributor may, in its sole discretion, waive the minimum initial investment requirement for Class Y shares.

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans are not permitted to establish new Class Z accounts, subject to certain exceptions described below.

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with the Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In addition, an omnibus retirement plan affiliated with a grandfathered plan may, in the sole discretion of the Distributor, open new Class Z accounts in a Fund after March 28, 2013 if the affiliated plan opened a Class Z account on or before March 28, 2013. If an omnibus retirement plan invested in Class Z shares changes recordkeepers after March 28, 2013, any new accounts established for that plan may not be established in Class Z shares but such a plan may establish new accounts in a different share class for which the plan is eligible. The Distributor may, in its sole discretion, delay the funding requirement described above for omnibus retirement plans to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with the Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

Effective March 29, 2013, accounts of selling agents (other than omnibus retirement plans, which are discussed above) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have received specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions). Effective March 29, 2013, such accounts may, at their holder’s option, exchange Class Z shares of a Fund, without the payment of a sales charge, for Class A shares of the same Fund.

Additional Eligible Investors

In addition, the Distributor, in its sole discretion, may accept investments in any share class from investors other than those listed in this prospectus.

Minimum Initial Investments

The table below shows the Fund’s minimum initial investment requirements, which may vary by Fund, class and type of account.

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Minimum Initial Investment

	Minimum Initial Investment(a)			Minimum Initial Investment for Accounts with Systematic Investment Plans(a)
For all Funds, classes and account types except those listed below	$	2,000		$	100
Individual Retirement Accounts for all Funds and classes except those listed below	$	1,000		$	100
Class I, Class R and Class R4		None			None
Class R5		variable	(b)		N/A
Class Y		variable	(c)		N/A
Class Z		variable	(d)		variable	(d)

^(a)  If your Class A, Class B, Class C or Class Z shares account balance falls below the minimum initial investment amount for any reason, including a market decline, you may be asked to increase it to the minimum initial investment amount or establish a monthly Systematic Investment Plan. If you open an account below the minimum initial investment amount by establishing a systematic investment plan, the plan must be established to invest on at least a monthly basis.

^(b)  There is no minimum initial investment in Class R5 shares for omnibus retirement plans. A minimum initial investment of $100,000 applies to aggregate purchases of Class R5 shares of a Fund for combined underlying accounts of any registered investment adviser that clears Fund share transactions for its client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements.

^(c)  There is no minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of at least $10 million as of the date of funding the Fund account. The minimum initial investment in Class Y shares for omnibus retirement plans with plan assets of less than $10 million as of the date of funding is $500,000.

^(d)  The minimum initial investment amount for Class Z shares is $0, $1,000 or $2,000 depending upon the category of eligible investor. See – Class Z Shares Minimum Initial Investments below.

The minimum initial investment requirements may be waived for accounts that are managed by an investment professional, for accounts held in approved discretionary or non-discretionary wrap programs, or for accounts that are a part of an employer-sponsored retirement plan. The Distributor, in its sole discretion, may also waive minimum initial investment requirements for other account types.

Minimum investment and related requirements may be modified at any time, with or without prior notice. If your account is closed and then re-opened with a systematic investment plan, your account must meet the then-current applicable minimum initial investment.

Class Z Shares Minimum Initial Investments

There is no minimum initial investment in Class Z shares for the following categories of eligible investors:

• Any person investing all or part of the proceeds of a distribution, rollover or transfer of assets into a Columbia Management Individual Retirement Account, from any deferred compensation plan which was a shareholder of any of the Funds of Columbia Acorn Trust on September 29, 2000, in which the investor was a participant and through which the investor invested in one or more of the Funds of Columbia Acorn Trust immediately prior to the distribution, transfer or rollover.

• Any health savings account sponsored by a third party platform.

• Any investor participating in a wrap program sponsored by a selling agent or other entity that is paid an asset-based fee by the investor and that is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any Trustee (or family member) of Columbia Acorn Trust.

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• Any employee (or family member) of the Investment Manager.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $1,000:

• Any individual retirement plan for which a selling agent or other entity provides services and is not compensated by the Fund for those services, other than in the form of payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the funds using the name “Columbia” prior to September 27, 2010 (Legacy Columbia Funds), other than the Columbia Acorn Funds, or (ii) the former distributor or transfer agent of the Legacy Columbia Funds, and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through an individual retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any shareholder (as well as any family member of a shareholder or person listed on an account registration for any account of the shareholder) of another fund distributed by the Distributor (i) who holds Class Z shares; (ii) who held Primary A shares prior to the share class redesignation of Primary A shares as Class Z shares that occurred on August 22, 2005; (iii) who holds Class A shares that were obtained by an exchange of Class Z shares; or (iv) who bought shares of certain mutual funds that were not subject to sales charges and that merged with a Legacy Columbia Fund distributed by the Distributor.

• Any investor participating in an account offered by a selling agent or other entity that provides services to such an account, is paid an asset-based fee by the investor and is not compensated by the Fund for those services, other than payments for shareholder servicing or sub-accounting performed in place of the Transfer Agent (each investor buying shares through a financial intermediary must independently satisfy the minimum investment requirement noted above).

• Any institutional investor who is a corporation, partnership, trust, foundation, endowment, institution, government entity, or similar organization, which meets the respective qualifications for an accredited investor, as defined under the Securities Act of 1933.

• Certain financial institutions and intermediaries, such as insurance companies, trust companies, banks, endowments, investment companies or foundations, buying shares for their own account, including Ameriprise Financial and its affiliates and/or subsidiaries.

• Any employee of Columbia Management Investment Advisers, LLC, the Distributor or the Transfer Agent and immediate family members of any of the foregoing who share the same address and any persons employed as of April 30, 2010 by (i) the former investment manager of the Legacy Columbia Funds (other than the Columbia Acorn Funds), or (ii) the former distributor or transfer agent of the Legacy Columbia Funds and immediate family members of any of the foregoing who share the same address are eligible to make new and subsequent purchases in Class Z shares through a non-retirement account. If you maintain your account with a selling agent, you must contact that selling agent each time you seek to purchase shares to notify them that you qualify for Class Z shares.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor (other than the Columbia Acorn Funds).

• Certain other investors as set forth in more detail in the SAI.

Systematic Investment Plan

The Systematic Investment Plan allows you to schedule regular purchases via automatic transfers from your bank account to the Fund on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your selling agent to set up the plan. Systematic Investment Plans may not be available for all share classes.

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Dividend Diversification

Generally, you may automatically invest distributions made by another Fund into the same class of shares (and in some cases certain other classes of shares) of a Fund at no additional sales charge. A sales charge may apply when you invest distributions made with respect to shares that were not subject to a sales charge at the time of your initial purchase. Call the Transfer Agent at 800.345.6611 for details.

Other Purchase Rules You Should Know

• Once the Transfer Agent or your selling agent receives your buy order in “good form,” your purchase will be made at the next calculated public offering price per share, which is the net asset value per share plus any sales charge that applies.

• You generally buy Class A shares at the public offering price per share because purchases of these share classes are generally subject to a front-end sales charge.

• You buy Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z shares at net asset value per share because no front-end sales charge applies to purchases of these share classes.

• The Distributor and the Transfer Agent reserve the right to cancel your order if the Fund doesn’t receive payment within three business days of receiving your buy order. The Fund will return any payment received for orders that have been cancelled, but no interest will be paid on that money.

• Selling agents are responsible for sending your buy orders to the Transfer Agent and ensuring that we receive your money on time.

• Shares purchased are recorded on the books of the Fund. The Fund doesn’t issue certificates.

Selling Shares

When you sell your shares, the Fund is effectively buying them back from you. This is called a redemption. You may sell your shares at any time. The payment will be sent within seven days after your request is received in “good form.” When you sell shares, the amount you receive may be more or less than the amount you invested. Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

The Systematic Withdrawal Plan allows you to schedule regular redemptions from your Class A, Class B, Class C, Class Y and/or Class Z shares account any day of the month on a monthly, quarterly or semi-annual basis. Contact the Transfer Agent or your financial advisor to set up the plan.

To set up the plan, your account balance must meet the class minimum initial investment amount. All dividend and capital gain distributions must be reinvested to set up the plan. A Systematic Withdrawal Plan cannot be set up on an account that already has a Systematic Investment Plan established. If you set up the plan after you’ve opened your account, we may require your signature to be Medallion Signature Guaranteed.

You can choose to receive your withdrawals via check or direct deposit into your bank account. The Fund will deduct any applicable CDSC from the withdrawals before sending the balance to you. You can cancel the plan by giving the Fund 30 days notice in writing or by calling the Transfer Agent at 800.422.3737. It’s important to remember that if you withdraw more than your investment in the Fund is earning, you’ll eventually withdraw your entire investment.

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In-Kind Redemptions

The Fund reserves the right to honor redemption orders with in-kind distributions of portfolio securities instead of cash. In the event the Fund distributes portfolio securities in-kind, you may incur the brokerage and transaction costs associated with converting the portfolio securities you receive into cash. Also, the portfolio securities you receive may increase or decrease in value before you convert them into cash. For U.S. federal income tax purposes redemptions paid in securities are generally treated the same as redemptions paid in cash.

Other Redemption Rules You Should Know

• Once the Transfer Agent or your selling agent receives your redemption order in “good form,” your shares will be sold at the next calculated NAV per share. Any applicable CDSC will be deducted from the amount you’re selling and the balance will be remitted to you.

• If you sell your shares directly through the Funds, we will normally send the redemption proceeds by mail or electronically transfer them to your bank account within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you sell your shares through a selling agent, the Funds will normally send the redemption proceeds by Fedwire within three business days after the Transfer Agent or your selling agent receives your order in “good form.”

• If you paid for your shares by check or from your bank account as an Automated Clearing House (ACH) transaction, the Funds will hold the redemption proceeds when you sell those shares for a period of time after the trade date of the purchase.

• No interest will be paid on uncashed redemption checks.

• The Funds can delay payment of the redemption proceeds for up to seven days and may suspend redemptions and/or further postpone payment of redemption proceeds when the NYSE is closed or during emergency circumstances as determined by the SEC.

• Other restrictions may apply to retirement accounts. For information about these restrictions, contact your retirement plan administrator.

• The Fund reserves the right to redeem your shares if your account falls below the Fund’s minimum initial investment requirement.

Exchanging Shares

You can generally sell shares of a Fund to buy shares of another Fund, in what is called an exchange. You should read the prospectus of, and make sure you understand the investment objective, principal investment strategies, risks, fees and expenses of, the Fund into which you are exchanging. You may be subject to a sales charge if you exchange from a money market Fund or any other Fund that does not charge a front-end sales charge into a non-money market Fund. If you hold your Fund shares through certain selling agents, including Ameriprise Financial Services, Inc., you may have limited exchangeability among the Funds. Please contact your selling agent for more information.

You can generally make exchanges between like share classes of any Fund and, subject to eligibility requirements, other share classes of any Fund. Some exceptions apply. Although the Funds allow certain exchanges from one share class to another share class with higher expenses, you should consider the expenses of each class before making such an exchange.

Systematic Exchanges

You may buy Class A, Class C, Class Y and/or Class Z shares of a Fund by exchanging each month from another Fund for shares of the same class of the Fund at no additional cost, subject to the following exchange amount minimums: $50 each month for individual retirement accounts (i.e. tax qualified accounts); and $100 each month for non-retirement accounts. Contact the

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Transfer Agent or your selling agent to set up the plan. If you set up your plan to exchange more than $100,000 each month, you must obtain a Medallion Signature Guarantee.

Exchanges will continue as long as your balance is sufficient to complete the systematic monthly transfers. You may terminate the program or change the amount you would like to exchange (subject to the $50 and $100 minimum requirements noted immediately above) by calling the Transfer Agent at 800.345.6611. A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase.

Other Exchange Rules You Should Know

• Exchanges are made at the NAV next calculated after your exchange order is received in “good form.”

• Once the Fund receives your exchange request, you cannot cancel it after the market closes.

• The rules for buying shares of a Fund generally apply to exchanges into that Fund, including, if your exchange creates a new Fund account, it must satisfy the minimum investment amount, unless a waiver applies.

• Shares of the purchased Fund may not be used on the same day for another exchange or sale.

• If you exchange shares from Class A shares of a money market Fund to a non-money market Fund, any further exchanges must be between shares of the same class. For example, if you exchange from Class A shares of a money market Fund into Class C shares of a non-money market Fund, you may not exchange from Class C shares of that non-money market Fund back to Class A shares of a money market Fund.

• A sales charge may apply when you exchange shares of a Fund that were not assessed a sales charge at the time of your initial purchase. For example, if your initial investment was in a money market Fund and you exchange into a non-money market Fund, your transaction is subject to a front-end sales charge if you exchange into Class A shares and to a CDSC if you exchange into Class C shares of the Funds.

• If your initial investment was in Class A shares of a non-money market Fund and you exchange shares into a money market Fund, you may exchange that amount to another Fund, including dividends earned on that amount, without paying a sales charge.

• If your shares are subject to a CDSC, you will not be charged a CDSC upon the exchange of those shares. Any CDSC will be deducted when you sell the shares you received from the exchange. The CDSC imposed at that time will be based on the period that begins when you bought shares of the original Fund and ends when you sell the shares of the Fund you received from the exchange. The applicable CDSC will be the CDSC of the original Fund.

• You may make exchanges only into a Fund that is legally offered and sold in your state of residence. Contact the Transfer Agent or your selling agent for more information.

• You generally may make an exchange only into a Fund that is accepting investments.

• The Fund may change or cancel your right to make an exchange by giving the amount of notice required by regulatory authorities (generally 60 days for a material change or cancellation).

• Unless your account is part of a tax-advantaged arrangement, an exchange for shares of another Fund is a taxable event, and you may recognize a gain or loss for tax purposes.

• Changing your investment to a different Fund will be treated as a sale and purchase, and you will be subject to applicable taxes on the sale and sales charges on the purchase of the new Fund.

• You may generally exchange Class T shares of a Fund for Class A shares of another Fund if the other Fund does not offer Class T shares. Class T shares exchanged into Class A shares cannot be exchanged back into Class T shares.

• Class Z shares of a Fund may be exchanged for Class A or Class Z shares of another Fund. In certain circumstances, the front-end sales charge applicable to Class A shares may be waived on exchanges of Class Z shares for Class A shares. See Buying, Selling and Exchanging Shares – Buying Shares – Eligible Investors – Class Z Shares for details.

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• You may not exchange Class B shares of one Columbia Acorn Fund for Class B shares of another Columbia Acorn Fund. However, you can generally sell Class B shares of Columbia Acorn Funds to buy Class B shares of another Fund (other than a Columbia Acorn Fund).

Same-Fund Exchange Privilege

Certain shareholders of a Fund may be or become eligible to invest in other classes of shares of the same Fund. Upon a determination of such eligibility, such shareholders may be eligible to exchange their shares for shares of the other share class, if offered. Such exchanges include exchanges of shares of one class for shares of another share class with higher expenses. Before making such an exchange, you should consider the expenses of each class. Investors should contact their selling agents to learn more about the details of the exchange privilege.

Note the following rules relating to same-Fund exchanges:

• No sales charges or other charges will apply to any such exchange, except that when Class B shares are exchanged, any CDSC applicable to Class B shares will be applied.

• Ordinarily, shareholders will not recognize a gain or loss for U.S. federal income tax purposes upon such an exchange. You should consult your tax advisor about your particular exchanges.

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Distributions and Taxes

Distributions to Shareholders

A mutual fund can make money two ways:

• It can earn income on its investments. Examples of fund income are interest paid on money market instruments and bonds, and dividends paid on common stocks.

• A mutual fund can also have capital gains if the value of its investments increases. While a fund continues to hold an investment, any gain is unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than it originally paid. Capital gains are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term gains) or more than one year (long-term gains).

FUNDamentals^TM

Distributions

Mutual funds make payments of fund earnings to shareholders, distributing them among all shareholders of the fund. As a shareholder, you are entitled to your portion of a fund’s distributed income, including capital gains.

Reinvesting your distributions buys you more shares of a fund – which lets you take advantage of the potential for compound growth. Putting the money you earn back into your investment means it, in turn, may earn even more money. Over time, the power of compounding has the potential to significantly increase the value of your investment. There is no assurance, however, that you’ll earn more money if you reinvest your distributions rather than receive them in cash.

The Fund intends to pay out, in the form of distributions to shareholders, a sufficient amount of its income and gains so that the Fund will qualify for treatment as a regulated investment company and generally will not have to pay any federal excise tax. The Fund generally intends to distribute any net realized capital gain (whether long-term or short-term gain) at least once a year. Normally, the Fund will declare and pay distributions of net investment income according to the following schedule:

Declaration and Distribution Schedule

Declarations	semi-annually
Distributions	semi-annually

The Fund may, however, declare or pay distributions of net investment income more frequently.

Different share classes of the Fund usually pay different net investment income distribution amounts, because each class has different expenses. Each time a distribution is made, the net asset value per share of the share class is reduced by the amount of the distribution.

The Fund generally pays cash distributions within five business days after the distribution was declared (or, if the Fund declares distributions daily, within five business days after the end of the month in which the distribution was declared). If you sell all of your shares after the record date, but before the payment date, for a distribution, you’ll normally receive that distribution in cash within five business days after the sale was made.

The Fund will automatically reinvest distributions in additional shares of the same share class of the Fund unless you inform us you want to receive your distributions in cash (the selling agent through which you purchased shares may have different policies). You can do this by contacting the Funds at the addresses and telephone numbers listed at the beginning of the section entitled Choosing a Share Class. No sales charges apply to the purchase or sale of such shares.

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For accounts held directly with the Fund, distributions of $10 or less will automatically be reinvested in additional Fund shares only. If you elect to receive distributions by check and the check is returned as undeliverable, all subsequent distributions will be reinvested in additional shares of the Fund.

Unless you are a tax-exempt investor or holding Fund shares through a tax-advantaged account (such as a 401(k) plan or IRA), you should consider avoiding buying Fund shares shortly before the Fund makes a distribution (other than distributions of net investment income that are declared daily) of net investment income or net realized capital gain, because doing so can cost you money in taxes to the extent the distribution consists of taxable income or gains. This is because you will, in effect, receive part of your purchase price back in the distribution. This is known as “buying a dividend.” To avoid “buying a dividend,” before you invest check the Fund’s distribution schedule, which is available at the Funds’ website and/or by calling the Funds’ telephone number listed at the beginning of the section entitled Choosing a Share Class.

If you buy shares of the Fund when it holds securities with unrealized capital gain, you may, in effect, receive part of your purchase price back if and when the Fund sells those securities and distributes any net realized capital gain. Any such distribution is generally subject to tax. The Fund may have, or may build up over time, high levels of unrealized capital gain. If you buy shares of the Fund when it has capital loss carryforwards, the Fund may have the ability to offset capital gains realized by the Fund that otherwise would have been distributed to shareholders. These losses may be subject to certain limitations.

Taxes and Your Investment

You should be aware of the following considerations applicable to all Funds (unless otherwise noted):

• The Fund intends to qualify each year as a regulated investment company. A regulated investment company generally is not subject to tax at the fund level on income and gains from investments that are distributed to shareholders. However, the Fund’s failure to qualify as a regulated investment company would result in Fund level taxation, and consequently, a reduction in income available for distribution to you.

• Distributions generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares.

• Distributions of the Fund’s ordinary income and net short-term capital gain, if any, generally are taxable to you as ordinary income. Distributions of the Fund’s net long-term capital gain, if any, generally are taxable to you as long-term capital gain. Whether capital gains are long-term or short-term is determined by how long the Fund has owned the investments that generated them, rather than how long you have owned your shares.

• From time to time, a distribution from the Fund could constitute a return of capital, which is not taxable to you so long as the amount of the distribution does not exceed your tax basis in your Fund shares. A return of capital reduces your tax basis in your Fund shares, with any amounts exceeding such basis generally taxable as capital gain.

• For taxable years beginning on or before December 31, 2012, if you are an individual and you meet certain holding period and other requirements for your Fund shares, a portion of your distributions may be treated as “qualified dividend income” taxable at lower net long-term capital gain rates. Qualified dividend income is income attributable to the Fund’s dividends received from certain U.S. and foreign corporations, as long as the Fund meets certain holding period and other requirements for the stock producing such dividends. The special tax treatment of qualified dividend income and the reduced tax rates applicable to long-term capital gain (described below) will expire for taxable years beginning on or after January 1, 2013, unless Congress enacts legislation providing otherwise.

• For taxable years beginning on or before December 31, 2012, generally the top individual U.S. federal income tax rate on net long-term capital gain (and qualified dividend income) has been reduced to 15% (0% for individuals in the 10% and 15% Federal income tax brackets). For taxable years beginning on or after January 1, 2013, the top individual U.S. federal income tax rate on net long-term capital gain is scheduled to rise to 20% unless Congress enacts legislation providing otherwise.

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• Certain derivative instruments when held in a Fund’s portfolio subject the Fund to special tax rules, the effect of which may be to, among other things, accelerate income to the Fund, defer Fund losses, cause adjustments in the holding periods of Fund portfolio securities, or convert capital gains into ordinary income, short-term capital losses into long-term capital losses or long-term capital gains into short-term capital gains. These rules could therefore affect the amount, timing and/or character of distributions to shareholders.

• Certain Funds may purchase or sell (write) options, as described further in the SAI. In general, option premiums which may be received by the Fund are not immediately included in the income of the Fund. Instead, such premiums are taken into account when the option contract expires, the option is exercised by the holder, or the Fund transfers or otherwise terminates the option. If an option written by a Fund is exercised and such Fund sells or delivers the underlying security, the Fund generally will recognize capital gain or loss equal to (a) the sum of the exercise price and the option premium received by the Fund minus (b) the Fund’s basis in the security. Such capital gain or loss generally will be short-term or long-term depending upon the holding period of the underlying security. Capital gains or losses with respect to any termination of a Fund’s obligation under an option other than through the exercise of the option and the related sale or delivery of the underlying security generally will be short-term gains or losses. Thus, for example, if an option written by a Fund expires unexercised, such Fund generally will recognize short-term capital gains equal to the premium received.

• A sale, redemption or exchange of Fund shares is a taxable event. This includes redemptions where you are paid in securities. Your sales, redemptions and exchanges of Fund shares (including those paid in securities) usually will result in a taxable capital gain or loss to you, equal to the difference between the amount you receive for your shares (or are deemed to have received in the case of exchanges) and the amount you paid (or are deemed to have paid in the case of exchanges) for them. Any such capital gain or loss generally will be long-term capital gain or loss if you have held your Fund shares for more than one year at the time of sale or exchange. In certain circumstances, capital losses may be converted from short-term to long-term; in other circumstances, capital losses may be disallowed under the “wash sale” rules.

• The Fund is required by federal law to withhold tax on any taxable and possibly tax-exempt distributions and redemption proceeds paid to you (including amounts paid to you in securities and amounts deemed to be paid to you upon an exchange of shares) if: you haven’t provided a correct TIN or haven’t certified to the Fund that withholding doesn’t apply; the Internal Revenue Service (IRS) has notified us that the TIN listed on your account is incorrect according to its records; or the IRS informs the Fund that you are otherwise subject to backup withholding.

• Historically, the Fund has only been required to report to you and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. The Fund is subject to new reporting requirements for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012 and sold, redeemed or exchanged after that date. IRS regulations now generally require the Fund (or your selling agent, if you hold Fund shares through a selling agent) to provide you and the IRS, upon the sale, redemption or exchange of Fund shares, with cost basis information about those shares as well as information about whether any gain or loss is short- or long-term and whether any loss is disallowed under the “wash sale” rules. This reporting is not required for Fund shares held in a retirement or other tax-advantaged account. With respect to Fund shares in accounts held directly with the Fund, the Fund will calculate and report cost basis using the Fund’s default method of average cost, unless you instruct the Fund to use a different calculation method. The Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please see www.columbiamanagement.com or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting and other available methods for cost basis reporting and how to select or change a particular method or to choose specific shares to sell, redeem or exchange. If you hold Fund shares through a selling agent, you should contact your selling agent to learn about its cost basis reporting default method and the reporting elections available to your account. The Fund does not recommend any particular method of determining cost basis. Please consult your tax advisor to determine which available cost basis method is best for you. When completing your U.S. federal and state income tax returns, carefully review the cost basis and other information provided to you and make any additional basis, holding period or other adjustments that may be required.

• Effective for taxable years beginning on or after January 1, 2013, certain high-income individuals (as well as estates and trusts) will be subject to a new 3.8% Medicare contribution tax. For individuals, the 3.8% tax will apply to the lesser of (1) the amount by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment

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income.” Net investment income generally includes for this purpose dividends, including any capital gain dividends, paid by the Fund, and net capital gains recognized on the sale, redemption or exchange of shares of the Fund.

• For taxable years beginning after December 22, 2010, if the Fund is a “qualified fund of funds,” the Fund can elect to allow its shareholders the foreign tax credit without regard to the requirement that more than 50% of the value of its total assets consist of stock or securities in foreign corporations. The Fund will qualify as a “qualified fund of funds” if at least 50% of the Fund’s value of the total assets of which (at the close of each quarter of the taxable year) is represented by interests in other regulated investment companies.

• Because most of Columbia Thermostat Fund’s investments are in shares of the underlying Portfolio Funds, the tax treatment of the Fund’s gains, losses, and distributions may differ from the tax treatment that would apply if either the Fund invested directly in the types of securities held by the Portfolio Funds or the shareholders invested directly in the underlying Portfolio Funds. As a result, you may receive taxable distributions earlier and recognize higher amounts of capital gain or ordinary income than you otherwise would.

FUNDamentals^TM

Taxes

The information provided above is only a summary of how U.S. federal income taxes may affect your investment in the Fund. It is not intended as a substitute for careful tax planning. Your investment in the Fund may have other tax implications.

It does not apply to certain types of investors who may be subject to special rules, including foreign or tax-exempt investors or those holding Fund shares through a tax-advantaged account, such as a 401(k) plan or IRA.

Please see the SAI for more detailed tax information. You should consult with your own tax advisor about the particular tax consequences to you of an investment in the Fund, including the effect of any foreign, state and local taxes, and the effect of possible changes in applicable tax laws.

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Columbia Acorn Family of Funds

Prospectus November 8, 2012

For More Information

You’ll find more information about the Columbia Acorn Funds, the Columbia Funds and the Other Funds in the documents described below. Contact the Funds as follows to obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries:

By Mail:	Columbia Funds c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081
By Telephone:	800.345.6611
Online:	www.columbiamanagement.com

Annual and Semi-Annual Reports to Shareholders

Additional information about the Fund’s investments is available in the Fund’s annual and semi-annual reports to shareholders. In the annual report, you will find a discussion of the market conditions and investment strategies that significantly affected the Fund’s performance during its last fiscal year.

Shareholder Communications with the Board

The Fund’s Board of Trustees has adopted procedures by which shareholders may communicate with the Board. Shareholders who wish to communicate with the Board should send their written communications to the Board by mail, c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, IL 60606, Attention: Secretary. Shareholder communications must (i) be in writing, (ii) identify the Columbia Acorn Fund to which the communication relates and (iii) state the particular class of shares and number of shares held by the communicating shareholder.

Statement of Additional Information

The SAI provides more detailed information about the Fund and its policies. The SAI is legally part of this prospectus (incorporated by reference). A copy has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Fund (including this prospectus, the SAI and shareholder reports) at the SEC’s Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC’s website at http://www.sec.gov. You can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov or by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-1520.

For purposes of any electronic version of this prospectus, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this prospectus.

The investment company registration number of Columbia Acorn Trust, of which the Fund is a series, is 811-01829.

^©2012 Columbia Management Investment Distributors, Inc.

225 Franklin Street, Boston, MA 02110

800.345.6611 www.columbiamanagement.com

C-1598-99 A (11/12)

Columbia Management^®

COLUMBIA ACORN TRUST

Class A, Class B, Class C, Class I, Class R, Class R4, Class R5, Class Y and Class Z Shares

STATEMENT OF ADDITIONAL INFORMATION

May 1, 2012, as supplemented November 8, 2012

Equity Funds	Class A Shares	Class B Shares	Class C Shares	Class I Shares	Class R Shares	Class R4 Shares	Class R5 Shares	Class Y Shares	Class Z Shares
Columbia Acorn Fund	LACAX	LACBX	LIACX	CANIX	—	CEARX	CRBRX	CRBYX	ACRNX
Columbia Acorn International	LAIAX	LIABX	LAICX	CARIX	CACRX	CCIRX	CAIRX	CCYIX	ACINX
Columbia Acorn USA	LAUAX	LAUBX	LAUCX	CAUIX	—	CUSAX	CYSRX	CUSYX	AUSAX
Columbia Acorn Select	LTFAX	LTFBX	LTFCX	CACIX	—	CSSRX	CSLRX	CSLYX	ACTWX
Columbia Acorn International Select	LAFAX	LFFBX	LFFCX	CRSIX	—	CILRX	CRIRX	CSIRX	ACFFX
Columbia Acorn European Fund	CAEAX	—	CAECX	CAFIX	—	—	CAEEX	—	CAEZX
Columbia Acorn Emerging Markets Fund	CAGAX	—	CGMCX	CATIX	—	CAERX	CANRX	—	CEFZX
Fund of Funds
Columbia Thermostat Fund	CTFAX	CTFBX	CTFDX	—	—	CTORX	CQTRX	CYYYX	COTZX

This Statement of Additional Information (SAI) is not a prospectus, is not a substitute for reading any prospectus and is intended to be read in conjunction with the Funds’ prospectuses dated May 1, 2012 and November 8, 2012. The most recent annual reports for the Funds, which include the Funds’ audited financial statements dated December 31, 2011, as well as the most recent semiannual reports for the Funds, which include the Fund’s unaudited financial statements dated June 30, 2012, are incorporated by reference into this SAI. Class R5 shares of the Funds (other than Columbia Acorn International), and Class R4 and Class Y shares of each Fund, commenced operations as of the date of this SAI and do not yet have financial statements to report.

Copies of the Funds’ current prospectuses and annual and semiannual reports may be obtained without charge by writing Columbia Management Investment Services Corp., P.O. Box 8081, Boston, MA 02266-8081, by calling Columbia Funds at 800.345.6611 or by visiting the Columbia Funds website at www.columbiamanagement.com.

C-6519 D (11/12)

TABLE OF CONTENTS
SAI PRIMER		2
ABOUT THE TRUST		6
ABOUT THE FUNDS’ INVESTMENTS		7
Certain Investment Activity Limits		7
Fundamental and Non-Fundamental Investment Policies		7
Permissible Investments and Related Risks		14
Borrowings		51
Short Sales		51
Lending Securities		53
Portfolio Turnover		53
Disclosure of Portfolio Information		54
INVESTMENT ADVISORY AND OTHER SERVICES		58
The Investment Manager and Investment Advisory Services		58
The Administrator		66
The Principal Underwriter/Distributor		68
	Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest	70
Other Service Providers		75
Codes of Ethics		77
Proxy Voting Policies and Procedures		78
FUND GOVERNANCE		79
BROKERAGE ALLOCATION AND OTHER PRACTICES		94
Brokerage Commissions		97
Directed Brokerage		97
Securities of Regular Broker-Dealers		98
Additional Shareholder Servicing Payments		98
Additional Selling Agent Payments		100
Performance Disclosure		101
CAPITAL STOCK AND OTHER SECURITIES		102
Description of the Trust’s Shares		102
PURCHASE, REDEMPTION AND PRICING OF SHARES		105
Purchase and Redemption		105
Offering Price		106
TAXATION		109
CONTROL PERSONS AND PRINCIPAL SHAREHOLDERS		122
APPENDIX A — DESCRIPTIONS OF SECURITIES RATINGS		A-1
APPENDIX B — THE INVESTMENT MANAGER’S PROXY VOTING POLICY AND PROCEDURES MANUAL		B-1
APPENDIX C — INFORMATION REGARDING PENDING AND SETTLED LEGAL PROCEEDINGS		C-1
APPENDIX S — MORE INFORMATION ABOUT CHOOSING A SHARE CLASS		S-1

1

SAI PRIMER

The SAI is a part of the Funds’ registration statement that is filed with the SEC. The registration statement includes the Funds’ prospectuses, the SAI and certain exhibits. The SAI, and any supplements to it, can be found online at www.columbiamanagement.com, or by accessing the SEC’s website at www.sec.gov.

For purposes of any electronic version of this SAI, all references to websites, or universal resource locators (URLs), are intended to be inactive and are not meant to incorporate the contents of any website into this SAI.

The SAI generally provides additional information about the Funds that is not required to be in the Funds’ prospectuses. The SAI expands discussions of certain matters described in the Funds’ prospectuses and provides certain additional information about the Funds that may be of interest to some investors. Among other things, the SAI provides information about:

• the organization of the Trust;

• the Funds’ investments;

• the Funds’ investment adviser and other service providers, including roles and relationships of Ameriprise Financial and its affiliates, and conflicts of interest;

• the governance of the Funds;

• the Funds’ brokerage practices;

• the share classes offered by the Funds;

• the purchase, redemption and pricing of Fund shares; and

• the application of U.S. federal income tax laws.

Investors may find this information important and helpful. If you have any questions about the Funds, please call Columbia Funds at 800.345.6611 or contact your financial advisor.

Before reading the SAI, you should consult the Glossary below, which defines certain of the terms used in the SAI.

Glossary

1933 Act	Securities Act of 1933, as amended
1934 Act	Securities Exchange Act of 1934, as amended
1940 Act	Investment Company Act of 1940, as amended
Administration Agreement	The administration agreement between the Trust, on behalf of the Funds, and the Administrator
Administrator	Columbia Wanger Asset Management, LLC
Advisory Agreement	The investment advisory agreement between the Trust, on behalf of the Funds, and the Investment Manager
Ameriprise Financial	Ameriprise Financial, Inc.
Bank of America	Bank of America Corporation
Board	The Trust’s Board of Trustees
CMOs	Collateralized mortgage obligations
Code	Internal Revenue Code of 1986, as amended

2

Codes of Ethics	The codes of ethics approved and/or adopted by the Board pursuant to Rule 17j-1 under the 1940 Act
Columbia Acorn Funds, the Fund(s) or a Fund	One or more of the open-end management investment companies listed on the front cover of this SAI that are series of the Trust
Columbia Funds Complex	The fund complex that is comprised of the open-end investment management companies advised by the Investment Manager or its affiliates and principally underwritten by Columbia Management Investment Distributors, Inc., as that term is defined under Form N-1A, including the Columbia Funds Family
Columbia Funds Family	The fund complex that is comprised of the open-end investment management companies advised by the Investment Manager or its affiliates and principally underwritten by Columbia Management Investment Distributors, Inc., including funds using the Columbia, RiverSource, Threadneedle and Seligman brands
Columbia Funds	The funds using the Columbia, RiverSource, Seligman and Threadneedle brands, including the Columbia Acorn Funds, within the Columbia Funds Family
Columbia Management	Columbia Management Investment Advisers, LLC, the Sub-Administrator
CWAM	Columbia Wanger Asset Management, LLC, the Investment Manager and the Administrator
Custodian	JPMorgan
Distributor	Columbia Management Investment Distributors, Inc.
Distribution Agreement	The distribution agreement between the Trust, on behalf of the Funds, and the Distributor
Distribution Plan(s)	One or more of the plans adopted by the Board pursuant to Rule 12b-1 under the 1940 Act for the distribution of the Funds’ shares
DST/BFDS	DST Systems, Inc./Boston Financial Data Services, Inc.
FDIC	Federal Deposit Insurance Corporation
Fitch	Fitch Investors Service, Inc.
FHLMC	Federal Home Loan Mortgage Corporation
FNMA	Federal National Mortgage Association
The Fund(s) or a Fund	One or more of the open-end management investment companies listed on the front cover of this SAI that are series of the Trust
Fund(s) of Funds	One or more of the “funds of funds” in the Columbia Funds Family, including Columbia Thermostat Fund, that invests its assets in a mix of underlying funds, or Portfolio Funds
GNMA	Government National Mortgage Association
GSAL	Goldman Sachs Agency Lending, the Funds’ securities lending agent

3

Independent Trustee(s)	The Trustee(s) of the Board who are not “interested persons” of the Funds as defined in the 1940 Act
Interested Trustee(s)	The Trustee(s) of the Board who are “interested persons” of the Funds as defined in the 1940 Act
International/Global Equity Fund(s)	One or more of the international/global equity funds in the Columbia Funds Family
Investment Manager	Columbia Wanger Asset Management, LLC
IRS	United States Internal Revenue Service
JPMorgan	JPMorgan Chase Bank, N.A., the Custodian
LIBOR	London Interbank Offered Rate
MLP	Master Limited Partnership
Moody’s	Moody’s Investors Service, Inc.
NASDAQ	National Association of Securities Dealers Automated Quotations system
NRSRO	Nationally recognized statistical ratings organization (such as Moody’s, Fitch or S&P)
NSCC	National Securities Clearing Corporation
NYSE	New York Stock Exchange
Portfolio Fund(s)	One or more of the underlying mutual funds in which a Fund of Funds, including Columbia Thermostat Fund, invests all or a portion of its assets
Principal Underwriter	Columbia Management Investment Distributors, Inc.
REIT	Real estate investment trust
REMIC	Real estate mortgage investment conduit
RIC	A “regulated investment company,” as such term is used in the Code
S&P	Standard & Poor’s Corporation, “Standard & Poor’s” and “S&P” are trademarks of The McGraw-Hill Companies, Inc. and have been licensed for use by the Investment Manager. The Columbia Funds are not sponsored, endorsed, sold or promoted by Standard & Poor’s and Standard & Poor’s makes no representation regarding the advisability of investing in the Columbia Funds.
SAI	This Statement of Additional Information
SEC	United States Securities and Exchange Commission
Selling Agent(s)	Banks, other financial institutions, broker-dealers and financial advisors, as well as firms that employ such broker-dealers and financial advisors, including, for example, brokerage firms, banks, investment advisers, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.
State Street	State Street Bank and Trust Company, the Funds’ custodian prior to July 22, 2011
Sub-Administrator	Columbia Management

4

Transfer Agency Agreement	The transfer agency agreement between the Trust, on behalf of the Funds, and Columbia Management Investment Services Corp.
Transfer Agent	Columbia Management Investment Services Corp.
The Trust	Columbia Acorn Trust, the open-end registered investment company to which this SAI relates
Trustee(s)	One or more of the Board’s Trustees

5

ABOUT THE TRUST

The Trust is a registered investment company under the 1940 Act within the Columbia Funds Family.

The Trust was organized as a Massachusetts business trust on April 21, 1992 as successor to The Acorn Fund, Inc., which became the Columbia Acorn series of Funds. Prior to October 13, 2003, the Trust was named Liberty Acorn Trust, and prior to September 29, 2000, it was named Acorn Investment Trust.

Each of the Funds is a series of the Trust. Each Fund operates as a diversified management investment company and has a fiscal year end of December 31^st. Prior to January 31, 2012, Columbia Acorn Select operated as a non-diversified investment company; it may not do so again without first obtaining shareholder approval.

The Funds offer the following classes of shares:

	Class A	Class B*	Class C	Class I	Class R	Class R4	Class R5**	Class Y	Class Z***
Columbia Acorn Fund	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn International	ü	ü	ü	ü	ü	ü	ü	ü	ü
Columbia Acorn USA	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn Select	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn International Select	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn European Fund	ü	—	ü	ü	—	—	ü	—	ü
Columbia Acorn Emerging Markets Fund	ü	—	ü	ü	—	ü	ü	—	ü
Columbia Thermostat Fund	ü	ü	ü	—	—	ü	ü	ü	ü

* The Funds no longer accept investments from new or existing investors in Class B shares. See the Funds’ prospectuses for details.

** Shareholders with Class R5 shares accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program. See the Funds’ prospectuses and Appendix S to this SAI for details.

*** Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013. See the Funds’ prospectuses and Appendix S to this SAI for details.

On September 29, 2000, the Funds (other than Columbia Acorn European Fund, Columbia Acorn Emerging Markets Fund and Columbia Thermostat Fund) changed their names, respectively, to Liberty Acorn Fund, Liberty Acorn International, Liberty Acorn USA, Liberty Acorn Foreign Forty and Liberty Acorn Twenty. Effective October 13, 2003, the Funds (except Columbia Acorn European Fund, Columbia Acorn Emerging Markets Fund and Columbia Thermostat Fund) and the Trust changed their names to their current names.

The Trust is not required to hold annual meetings of shareholders, but special meetings may be called for certain purposes. The last meeting to elect trustees was held on May 27, 2010. Shareholders receive one vote for each Fund share held. Shares of each Fund and any other series of the Trust that may be in existence from time to time generally vote together, except when required by law to vote separately by Fund or by class. Shareholders owning in the aggregate 10 percent or more of Trust shares may call meetings to consider removal of Trustees of the Trust. Under certain circumstances, the Trust will provide information to assist shareholders in calling such a meeting.

6

ABOUT THE FUNDS’ INVESTMENTS

The investment objective, principal investment strategies (i.e., as used in this SAI and the corresponding prospectuses, a strategy which generally involves the ability to invest 10% or more of a Fund’s total assets) and related principal investment risks for each Fund are discussed in each Fund’s prospectuses.

Certain Investment Activity Limits

The overall investment and other activities of the Investment Manager and its affiliates may limit the investment opportunities for each Fund in certain markets where limitations are imposed by regulators upon the amount of investment by affiliated investors, in the aggregate or in individual issuers. From time to time, each Fund’s activities also may be restricted because of regulatory restrictions applicable to the Investment Manager and its affiliates and/or because of their internal policies. See Investment Advisory and Other Services — Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest.

Fundamental and Non-Fundamental Investment Policies

The following discussion of “fundamental” and “non-fundamental” investment policies and limitations for each Fund supplements the discussion of investment policies in the Fund’s prospectuses. A fundamental policy may be changed only with Board and shareholder approval. A non-fundamental policy may be changed by the Board and does not require shareholder approval, but may require notice to shareholders in certain instances.

Unless otherwise noted, whenever an investment policy or limitation states a maximum percentage of a Fund’s assets that may be invested in any security or other asset, or sets forth a policy regarding an investment standard, compliance with such percentage limitation or standard will be determined solely at the time of the Fund’s acquisition of such security or asset. Borrowings and other instruments that may give rise to leverage and the restriction on investing in illiquid securities are monitored on an ongoing basis.

Fundamental Investment Policies

The 1940 Act provides that a “vote of a majority of the outstanding voting securities” means the affirmative vote of the lesser of (1) more than 50% of the outstanding shares of a Fund, or (2) 67% or more of the shares present at a meeting if more than 50% of the outstanding shares are represented at the meeting in person or by proxy. The following fundamental investment policies cannot be changed without such a vote.

Columbia Acorn Fund may not, as a matter of fundamental policy:

1. Invest more than 5% of its assets (valued at time of investment) in securities of any one issuer, except in government obligations;

2. Acquire securities of any one issuer which at the time of investment (a) represent more than 10% of the voting securities of the issuer or (b) have a value greater than 10% of the value of the outstanding securities of the issuer;

3. Invest more than 25% of its assets (valued at time of investment) in securities of companies in any one industry;

4. Invest more than 5% of its assets (valued at time of investment) in securities of issuers with less than three years’ operation (including predecessors);

5. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s assets at the time of borrowing, and (b) in connection with transactions in options and in securities index futures [the Fund will not purchase additional securities when its borrowings, less amounts receivable on sales of portfolio securities, exceed 5% of total assets];

7

6. Pledge, mortgage or hypothecate its assets, except in connection with permitted borrowings;

7. Underwrite the distribution of securities of other issuers; however, the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the Securities Act of 1933 on the ground that the Fund could be regarded as an underwriter as defined by that act with respect to such resale; but the Fund will limit its total investment in restricted securities and in other securities for which there is no ready market to not more than 10% of its total assets at the time of acquisition;

8. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises which invest in real estate or interests in real estate;

9. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) forward contracts;

10. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

11. Sell securities short or maintain a short position, except short sales “against the box;”

12. Participate in a joint or on a joint or several basis in any trading account in securities;

13. Invest in companies for the purpose of management or the exercise of control;

14. Issue any senior security except to the extent permitted under the Investment Company Act of 1940;

15. Make loans, but this restriction shall not prevent the Fund from (a) buying a part of an issue of bonds, debentures, or other obligations that are publicly distributed, or from investing up to an aggregate of 15% of its total assets (taken at market value at the time of each purchase) in parts of issues of bonds, debentures or other obligations of a type privately placed with financial institutions, (b) investing in repurchase agreements, or (c) lending portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (taken at market value at the time of such loan).

Columbia Acorn International may not, as a matter of fundamental policy:

1. With respect to 75% of the value of the Fund’s total assets, invest more than 5% of its total assets (valued at time of investment) in securities of a single issuer, except securities issued or guaranteed by the government of the U.S., or any of its agencies or instrumentalities;

2. Acquire securities of any one issuer that at the time of investment (a) represent more than 10% of the voting securities of the issuer or (b) have a value greater than 10% of the value of the outstanding securities of the issuer;

3. Invest more than 25% of its assets (valued at time of investment) in securities of companies in any one industry;

4. Make loans, but this restriction shall not prevent the Fund from (a) buying a part of an issue of bonds, debentures, or other obligations that are publicly distributed, or from investing up to an aggregate of 15% of its total assets (taken at market value at the time of each purchase) in parts of issues of bonds, debentures or other obligations of a type privately placed with financial institutions, (b) investing in repurchase agreements, or (c) lending portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (taken at market value at the time of such loan);

5. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s total assets at the time of borrowing, and (b) in connection with transactions in options, futures and options on futures. The Fund will not purchase additional securities when its borrowings, less amounts receivable on sales of portfolio securities, exceed 5% of total assets;

8

6. Underwrite the distribution of securities of other issuers; however the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the Securities Act of 1933 on the ground that the Fund could be regarded as an underwriter as defined by that act with respect to such resale; but the Fund will limit its total investment in restricted securities and in other securities for which there is no ready market, including repurchase agreements maturing in more than seven days, to not more than 15% of its total assets at the time of acquisition;

7. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises that invest in real estate or interests in real estate;

8. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) forward contracts;

9. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

10. Sell securities short or maintain a short position, except short sales “against the box;”

11. Issue any senior security except to the extent permitted under the Investment Company Act of 1940.

Columbia Acorn USA may not, as a matter of fundamental policy:

1. With respect to 75% of the value of the Fund’s total assets, invest more than 5% of its total assets (valued at time of investment) in securities of a single issuer, except securities issued or guaranteed by the government of the U.S., or any of its agencies or instrumentalities;

2. Acquire securities of any one issuer which at the time of investment (a) represent more than 10% of the voting securities of the issuer or (b) have a value greater than 10% of the value of the outstanding securities of the issuer;

3. Invest more than 25% of its assets (valued at time of investment) in securities of companies in any one industry, except that this restriction does not apply to investments in U.S. government securities;

4. Make loans, but this restriction shall not prevent the Fund from (a) buying a part of an issue of bonds, debentures, or other obligations that are publicly distributed, or from investing up to an aggregate of 15% of its total assets (taken at market value at the time of each purchase) in parts of issues of bonds, debentures or other obligations of a type privately placed with financial institutions, (b) investing in repurchase agreements, or (c) lending portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (taken at market value at the time of such loan);

5. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s total assets at the time of borrowing, and (b) in connection with transactions in options, futures and options on futures;

6. Underwrite the distribution of securities of other issuers; however, the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the Securities Act of 1933 on the ground that the Fund could be regarded as an underwriter as defined by that act with respect to such resale;

7. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises which invest in real estate or interests in real estate;

8. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) foreign currency contracts;

9. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

10. Issue any senior security except to the extent permitted under the Investment Company Act of 1940.

9

Columbia Acorn Select and Columbia Acorn International Select may not, as a matter of fundamental policy:

1. With respect to 75% of the value of the Fund’s total assets, invest more than 5% of its total assets (valued at the time of investment) in securities is of a single issuer, except securities issued or guaranteed by the government of the U.S., or any of its agencies or instrumentalities [this restriction applies only to Columbia Acorn International Select];

2. Acquire securities of any one issuer which at the time of investment (a) represent more than 10% of the voting securities of the issuer or (b) have a value greater than 10% of the value of the outstanding securities of the issuer;

3. With respect to 50% of the value of the Fund’s total assets, purchase the securities of any issuer (other than cash items and U.S. government securities and securities of other investment companies) if such purchase would cause the Fund’s holdings of that issuer to exceed 5% of the Fund’s total assets [this restriction applies only to Columbia Acorn Select];*

4. Invest more than 25% of its total assets in a single issuer (other than U.S. government securities);

5. Invest more than 25% of its total assets in the securities of companies in a single industry (excluding U.S. government securities);

6. Make loans, but this restriction shall not prevent the Fund from (a) investing in debt securities, (b) investing in repurchase agreements, or (c) lending its portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (taken at market value at the time of such loan);

7. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s total assets at the time of borrowing, and (b) in connection with transactions in options, futures and options on futures;

8. Underwrite the distribution of securities of other issuers; however, the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the Securities Act of 1933 on the ground that the Fund could be regarded as an underwriter as defined by that act with respect to such resale;

9. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises which invest in real estate or interests in real estate;

10. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) foreign currency contracts;

11. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

12. Issue any senior security except to the extent permitted under the Investment Company Act of 1940.

* As permitted by its fundamental policy regarding issuer concentration (which generally prohibits the Fund, with respect to 50% of its assets, from investing more than 5% of its assets in any one issuer, and which may not be changed without shareholder approval), Columbia Acorn Select became diversified effective January 31, 2012. The Fund may not resume operating in a non-diversified manner without first obtaining shareholder approval. Accordingly, with respect to 75% of its assets, the Fund may not invest more than 5% of its assets in any one issuer.

10

Columbia Acorn European Fund may not, as a matter of fundamental policy:

1. With respect to 75% of the value of the Fund’s total assets, invest more than 5% of its total assets (valued at time of investment) in securities of a single issuer, except securities issued or guaranteed by the government of the U.S. or any of its agencies or instrumentalities;

2. Acquire securities of any one issuer that at the time of investment (a) represent more than 10% of the voting securities of the issuer or (b) have a value greater than 10% of the value of the outstanding securities of the issuer;

3. Invest more than 25% of its total assets (valued at time of investment) in securities of companies in any one industry;

4. Make loans, but this restriction shall not prevent the Fund from (a) buying a part of an issue of bonds, debentures, or other obligations that are publicly distributed, or from investing up to an aggregate of 15% of its total assets (valued at the time of investment) in parts of issues of bonds, debentures or other obligations of a type privately placed with financial institutions, (b) investing in repurchase agreements, or (c) lending its portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (valued at the time of such loan);

5. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s total assets (valued at the time of such borrowing) and (b) in connection with transactions in options, futures and options on futures. The Fund will not purchase additional securities when its borrowings, less amounts receivable on sales of portfolio securities, exceed 5% of its total assets;

6. Underwrite the distribution of securities of other issuers; however the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the 1933 Act on the ground that the Fund could be regarded as an underwriter as defined by the 1933 Act with respect to such resale;

7. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises that invest in real estate or interests in real estate;

8. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) forward contracts;

9. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

10. Issue any senior security except to the extent permitted under the 1940 Act.

Columbia Acorn Emerging Markets Fund may not, as a matter of fundamental policy:

1. With respect to 75% of the value of the Fund’s total assets, invest more than 5% of its total assets (valued at time of investment) in securities of a single issuer, except securities issued or guaranteed by the government of the U.S. or any of its agencies or instrumentalities;

2. Acquire securities of any one issuer that at the time of investment (a) represent more than 10% of the voting securities of the issuer or (b) have a value greater than 10% of the value of the outstanding securities of the issuer;

3. Invest more than 25% of its total assets (valued at time of investment) in securities of companies in any one industry;

4. Make loans, but this restriction shall not prevent the Fund from (a) investing in debt securities, (b) investing in repurchase agreements, or (c) lending its portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (valued at the time of such loan);

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5. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s total assets (valued at the time of such borrowing) and (b) in connection with transactions in options, futures and options on futures. The Fund will not purchase additional securities when its borrowings, less amounts receivable on sales of portfolio securities, exceed 5% of its total assets;

6. Underwrite the distribution of securities of other issuers; however the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the 1933 Act on the ground that the Fund could be regarded as an underwriter as defined by the 1933 Act with respect to such resale;

7. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises that invest in real estate or interests in real estate;

8. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) forward contracts;

9. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

10. Issue any senior security except to the extent permitted under the 1940 Act.

Columbia Thermostat Fund will, as a matter of fundamental policy, concentrate its investments in shares of other mutual funds.

Columbia Thermostat Fund may not, as a matter of fundamental policy:

1. With respect to 75% of the value of the Fund’s total assets, invest more than 5% of its total assets (valued at time of investment) in securities of a single issuer, except shares of Portfolio Funds and securities issued or guaranteed by the government of the U.S., or any of its agencies or instrumentalities;

2. Make loans, but this restriction shall not prevent the Fund from (a) buying a part of an issue of bonds, debentures, or other obligations that are publicly distributed, or from investing up to an aggregate of 15% of its total assets (taken at market value at the time of each purchase) in parts of issues of bonds, debentures or other obligations of a type privately placed with financial institutions, (b) investing in repurchase agreements, or (c) lending portfolio securities, provided that it may not lend securities if, as a result, the aggregate value of all securities loaned would exceed 33% of its total assets (taken at market value at the time of such loan);

3. Borrow money except (a) from banks for temporary or emergency purposes in amounts not exceeding 33% of the value of the Fund’s total assets at the time of borrowing, and (b) in connection with transactions in options, futures and options on futures;

4. Underwrite the distribution of securities of other issuers; however, the Fund may acquire “restricted” securities which, in the event of a resale, might be required to be registered under the Securities Act of 1933 on the ground that the Fund could be regarded as an underwriter as defined by that act with respect to such resale;

5. Purchase and sell real estate or interests in real estate, although it may invest in marketable securities of enterprises which invest in real estate or interests in real estate;

6. Purchase and sell commodities or commodity contracts, except that it may enter into (a) futures and options on futures and (b) forward contracts;

7. Make margin purchases of securities, except for use of such short-term credits as are needed for clearance of transactions and except in connection with transactions in options, futures and options on futures;

8. Sell securities short or maintain a short position, except short sales “against the box;”

9. Invest in companies for the purpose of management or the exercise of control;

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10. Issue any senior security except to the extent permitted under the 1940 Act;

11. Invest 25% or more of its total assets in the securities of a single industry (excluding U.S. Government securities and securities of other investment companies).

Non-Fundamental Investment Policies

Each Fund, as a matter of non-fundamental policy, may not:

1. Acquire securities of other registered investment companies except in compliance with the 1940 Act;

2. Invest in companies for the purpose of management or the exercise of control;

3. Invest more than 15% of its net assets (valued at time of investment) in illiquid securities, including repurchase agreements maturing in more than seven days; or

4. Make short sales of securities unless the Fund owns at least an equal amount of such securities, or owns securities that are convertible or exchangeable, without payment of further consideration, into at least an equal amount of such securities.

Each Fund, except Columbia Acorn Fund, as a matter of non-fundamental policy, may not: pledge, mortgage or hypothecate its assets, except as may be necessary in connection with permitted borrowings or in connection with short sales, options, futures and options on futures.

Each of Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA and Columbia Acorn Select, as a matter of non-fundamental policy, may not: acquire securities of other registered open-end investment companies or registered unit investment trusts in reliance on Sections (12)(d)(1)(F) or (G) of the 1940 Act.

Each of Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA and Columbia Thermostat Fund, as a matter of non-fundamental policy, may not: invest more than 10% of its total assets (valued at the time of investment) in restricted securities, and in any event subject to the Fund’s policy regarding investments in illiquid securities.

Each of Columbia Acorn Fund and Columbia Acorn Select, as a matter of non-fundamental policy, may not: invest more than 33% of its total assets (valued at time of investment) in securities of foreign issuers.

Each of Columbia Acorn International and Columbia Acorn International Select, as a matter of non-fundamental policy, may not: invest more than 25% of its total assets in domestic securities, under normal market conditions.

Columbia Acorn USA, as a matter of non-fundamental policy, may not:

1. Under normal circumstances, invest less than 80% of its net assets (plus any borrowings for investment purposes) in domestic securities [the Fund will notify shareholders at least 60 days prior to any change in this policy]; or

2. Invest more than 10% of its total assets (valued at the time of investment) in securities of foreign issuers, not including securities represented by American Depository Receipts.

Columbia Acorn International Select, as a matter of non-fundamental policy, may not: under normal circumstances, invest less than 65% of its net assets in the securities of foreign companies based in developed markets outside the United States.

Columbia Acorn European Fund, as a matter of non-fundamental policy, may not:

1. Under normal circumstances, invest less than 80% of its net assets (plus any borrowings for investment purposes) in European companies. For purposes of these non fundamental policies, the Fund may invest in a

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company if (i) it is domiciled in, or the principal trading market for its securities is in, a European country, (ii) it derives 50% or more of its economic value from goods produced, sales made or services performed in a European country or has at least 50% of its assets in a European country or (iii) it is a holding company that predominately holds shares in such companies. The Fund will notify shareholders at least 60 days prior to any change in this policy;

2. Under normal circumstances, invest less than 70% of its total assets in companies in Western European countries (for example, the United Kingdom, Germany, France and Italy), or more than 30% of its total assets in companies in emerging Central and Eastern European countries (for example, Poland, the Czech Republic, Turkey and Cyprus), including up to 10% of its total assets in companies in Russia and the Ukraine; or

3. Invest more than 10% of its total assets (valued at the time of investment) in securities of domestic issuers.

Columbia Acorn Emerging Markets Fund, as a matter of non-fundamental policy, may not:

1. Under normal circumstances, invest less than 80% of its net assets (plus any borrowings for investment purposes) in companies located in emerging market countries, including frontier market countries. Emerging market countries are those countries whose economies are developing or emerging from underdevelopment (for example, China, India, Poland and Turkey). Frontier emerging market countries generally have smaller economies and even less developed capital markets than traditional emerging market countries (for example, Vietnam, Columbia, Nigeria and Kazakhstan). For purposes of this non-fundamental policy, the Fund may invest in a company if (i) it is domiciled in, or the principal trading market for its securities is in, an emerging market country, (ii) it derives 50% or more of its economic value from goods produced, sales made or services performed or has at least 50% of its assets in an emerging market country or countries or (iii) it is a holding company that predominantly holds shares in such companies. The Fund will notify shareholders at least 60 days prior to any change in this policy; or

2. Invest more than 10% of its total assets (valued at the time of investment) in securities of domestic issuers.

Investment Restrictions of the Portfolio Funds

For the Portfolio Funds’ investment policies, refer to their respective statements of additional information, which are available on the Columbia Funds website at www.columbiamanagement.com and on the SEC’s website at www.sec.gov.

Under certain circumstances, a Portfolio Fund may determine to make payment of a redemption request by Columbia Thermostat Fund wholly or partly by a distribution in-kind of securities from its portfolio, instead of cash, in accordance with the rules of the SEC. In such cases, the Fund may hold securities distributed by a Portfolio Fund until the Investment Manager determines that it is appropriate to dispose of such securities.

Permissible Investments and Related Risks

Each Fund’s prospectuses identify and summarize the individual types of securities in which the Fund invests as part of its principal investment strategies and the principal risks associated with such investments. In this section the term “Fund” refers to a Fund or a Portfolio Fund, except where otherwise indicated.

The 1940 Act normally prohibits mutual funds from investing in other mutual funds beyond certain limits. Because Columbia Thermostat Fund is a Fund of Funds, it takes advantage of a rule under the 1940 Act that allows it to exceed those limits subject to certain conditions. Accordingly, Columbia Thermostat Fund may: (i) own more than 3% of the total outstanding stock of a Portfolio Fund; (ii) invest more than 5% of its total assets in any one such Portfolio Fund; and (iii) invest more than 10% of its total assets, collectively, in Portfolio Fund shares. See About the Funds’ Investments — Permissible Fund Investments — Investments in Other Investment Companies for information.

As of the date of this SAI, and as discussed in the Fund’s prospectuses, Columbia Thermostat Fund may invest in the following Portfolio Funds: Columbia Acorn Fund, Columbia Acorn Select, Columbia Acorn

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International, Columbia Dividend Income Fund, Columbia Large Cap Enhanced Core Fund, Columbia Contrarian Core Fund, Columbia Select Large Cap Growth Fund, Columbia Intermediate Bond Fund, Columbia Income Opportunities Fund and Columbia U.S. Treasury Index Fund.

The table below identifies for each Fund, or in the case of Columbia Thermostat Fund, for each Portfolio Fund, certain types of securities in which it is permitted to invest, including those described in each Fund’s prospectuses. A Fund generally has the ability to invest 10% or more of its total assets in each type of security described in its prospectuses (and in each sub-category of such security type described in this SAI). To the extent that a type of security identified below for a Fund is not described in the Fund’s prospectuses (or as a sub-category of such security type in this SAI), the Fund generally invests less than 10% of its total assets in such security type, except as noted below.

Information about individual types of securities (including certain of their associated risks) in which some or all of the Funds or Portfolio Funds may invest is set forth below. Each Fund’s investment in these types of securities is subject to its investment objective and fundamental and non-fundamental investment policies.

Temporary Defensive Positions. Each Fund may temporarily invest in money market instruments or hold cash or cash equivalents. Unless prohibited by its investment policies, certain Funds may also temporarily invest in derivatives, such as futures (i.e., index futures) or options on futures, for various purposes, including among others, investing in particular derivatives to achieve indirect investment exposures to a sector, country or region where the Investment Manager believes such defensive positioning is appropriate. It may do so without limit and for as long a period as deemed necessary, when the Investment Manager: (i) believes that the market conditions are not favorable for profitable investing; (ii) is unable to locate favorable investment opportunities; or (iii) determines that a temporary defensive position is advisable or necessary in order to meet anticipated redemption requests, or for other reasons. While a Fund engages in such strategies, it may not achieve its investment objective. The Investment Manager currently expects that substantially all of each Fund’s assets will be invested in accordance with its principal investment strategies. As a result, the Funds expect to remain substantially exposed to the equity markets.

See also About the Funds’ Investments — Permissible Investments and Related Risks — Money Market Instruments.

Permissible Fund Investments

Investment Type	Columbia Acorn Fund	Columbia Acorn USA	Columbia Acorn Select	Columbia Acorn International	Columbia Acorn International Select	Columbia Acorn European Fund	Columbia Acorn Emerging Markets Fund	Columbia Thermostat Fund
Asset-Backed Securities	ü	ü	ü	ü	ü	ü	ü	ü
Bank Obligations (Domestic and Foreign)	ü	ü	ü	ü	ü	ü	ü	ü
Common Stock	ü	ü	ü	ü	ü	ü	ü	ü
Convertible Securities	ü	ü	ü	ü	ü	ü	ü	ü
Corporate Debt Securities	ü	ü	ü	ü	ü	ü	ü	ü
Custody Receipts and Trust Certificates	ü	ü	ü	ü	ü	ü	ü	ü
Derivatives
Index or Linked Securities (Structured Products)	ü	ü	ü	ü	ü	ü	ü	ü
Futures Contracts and Options on Futures Contracts	ü	ü	ü	ü	ü	ü	ü	ü
Stock Options and Stock Index Options	ü	ü	ü	ü	ü	ü	ü	ü

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Investment Type	Columbia Acorn Fund	Columbia Acorn USA	Columbia Acorn Select	Columbia Acorn International	Columbia Acorn International Select	Columbia Acorn European Fund	Columbia Acorn Emerging Markets Fund	Columbia Thermostat Fund
Swap Agreements	ü	ü	ü	ü	ü	ü	ü	ü
Dollar Rolls								ü
Foreign Currency Transactions	ü	ü	ü	ü	ü	ü	ü	ü
Foreign Securities	ü	ü	ü	ü	ü	ü	ü	ü
Guaranteed Investment Contracts								ü
Illiquid Securities	ü	ü	ü	ü	ü	ü	ü	ü
Initial Public Offerings	ü	ü	ü	ü	ü	ü	ü	ü
Investments in other Investment Companies	ü	ü	ü	ü	ü	ü	ü	ü
Low and Below Investment Grade Securities	ü	ü	ü	ü	ü	ü	ü	ü
Money Market Instruments	ü	ü	ü	ü	ü	ü	ü	ü
Mortgage-Backed Securities								ü
Municipal Securities								ü
Participation Interests	ü	ü	ü	ü	ü	ü	ü	ü
Preferred Stock	ü	ü	ü	ü	ü	ü	ü	ü
Private Placement and Other Restricted Securities	ü	ü	ü	ü	ü	ü	ü	ü
Real Estate Investment Trusts and Master Limited Partnerships*	ü	ü	ü	ü	ü	ü	ü	ü
Repurchase Agreements	ü	ü	ü	ü	ü	ü	ü	ü
Reverse Repurchase Agreements	ü	ü	ü	ü	ü	ü	ü	ü
Standby Commitments								ü
Stripped Securities	ü	ü	ü	ü	ü	ü	ü	ü
U.S. Government and Related Obligations	ü	ü	ü	ü	ü	ü	ü	ü
Variable- and Floating-Rate Obligations								ü
Warrants and Rights	ü	ü	ü	ü	ü	ü	ü	ü
When-Issued, Delayed Delivery and Forward Commitment Transactions	ü	ü	ü	ü	ü	ü	ü	ü
Zero-Coupon, Pay-in-Kind and Step-Coupon Securities	ü	ü	ü	ü	ü	ü	ü	ü

* Columbia Acorn International Select may generally invest up to 20% of its total assets in REITs and MLPs.

Asset-Backed Securities

Asset-backed securities represent interests in, or debt instruments that are backed by, pools of various types of assets that generate cash payments generally over fixed periods of time. Such securities entitle the security holders to receive distributions that are tied to the payments made on the underlying assets (less fees paid to the originator, servicer, or other parties, and fees paid for credit enhancement), so that the payments made on the underlying assets effectively pass through to such security holders. Asset-backed securities typically are created by an originator of loans or owner of accounts receivable that sells such underlying assets to a special purpose entity in a process called a

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securitization. The special purpose entity issues securities that are backed by the payments on the underlying assets, and have a minimum denomination and specific term. Asset-backed securities may be structured as fixed-, variable- or floating-rate obligations or as zero coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Securities, Permissible Fund Investments — Zero Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Investments — Private Placement and Other Restricted Securities for more information.

Investing in asset-backed securities is subject to certain risks. For example, the value of asset-backed securities may be affected by, among other factors, changes in: interest rates, the market’s assessment of the quality of underlying assets, the creditworthiness of the servicer for the underlying assets, information concerning the originator of the underlying assets, or the creditworthiness or rating of the entities that provide any supporting letters of credit, surety bonds, derivative instruments, or other credit enhancement. The value of asset-backed securities also will be affected by the exhaustion, termination or expiration of any credit enhancement.

Declining or low interest rates may lead to a more rapid rate of repayment on the underlying assets, resulting in accelerated payments on asset-backed securities that then would be reinvested at a lesser rate of interest. Rising or high interest rates tend to lead to a slower rate of repayment on the underlying assets, resulting in slower than expected payments on asset-backed securities that can, in turn, lead to a decline in value. The impact of changing interest rates on the value of asset-backed securities may be difficult to predict and result in greater volatility. Holders of asset-backed securities generally have no recourse against the originator of the underlying assets in the event of a default on the underlying assets. Credit risk is the risk that a holder of securities, backed by pools of receivables such as mortgage loans, may not receive all or part of its principal because the issuer, any credit enhancer and/or an underlying obligor has defaulted on its obligations. Credit risk is increased for asset-backed securities that are subordinated to another security (i.e., if the holder of an asset-backed security is entitled to receive payments only after payment obligations to holders of the other security are satisfied). The more deeply subordinated the security, the greater the credit risk associated with the security will be.

Bank Obligations (Domestic and Foreign)

Bank obligations include certificates of deposit, bankers’ acceptances, time deposits and promissory notes that earn a specified rate of return and may be issued by (i) a domestic branch of a domestic bank, (ii) a foreign branch of a domestic bank, (iii) a domestic branch of a foreign bank or (iv) a foreign branch of a foreign bank. Bank obligations may be structured as fixed-, variable- or floating-rate obligations. See Permissible Fund Investments — Variable- and Floating-Rate Obligations for more information.

Certificates of deposit, or so-called CDs, typically are interest-bearing debt instruments issued by banks and have maturities ranging from a few weeks to several years. Bankers’ acceptances are time drafts drawn on and accepted by banks, are a customary means of effecting payment for merchandise sold in import-export transactions and are a general source of financing. Yankee dollar certificates of deposit are negotiable CDs issued in the United States by branches and agencies of foreign banks. Eurodollar certificates of deposit are CDs issued by foreign (mainly European) banks with interest and principal paid in U.S. dollars. Such CDs typically have maturities of less than two years and have interest rates that typically are pegged to the London Interbank Offered Rate, or LIBOR. A time deposit can be either a savings account or CD that is an obligation of a financial institution for a fixed term. Typically, there are penalties for early withdrawals of time deposits. Promissory notes are written commitments of the maker to pay the payee a specified sum of money either on demand or at a fixed or determinable future date, with or without interest.

Bank investment contracts are issued by banks. Pursuant to such contracts, a Fund may make cash contributions to a deposit fund of a bank. The bank then credits to the Fund payments at floating or fixed interest rates. A Fund also may hold funds on deposit with its custodian for temporary purposes.

Investing in bank obligations is subject to certain risks. Certain bank obligations, such as some CDs, are insured by the FDIC up to certain specified limits. Many other bank obligations, however, are neither guaranteed

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nor insured by the FDIC or the U.S. Government. These bank obligations are “backed” only by the creditworthiness of the issuing bank or parent financial institution. Domestic and foreign banks are subject to different governmental regulation. Accordingly, certain obligations of foreign banks, including Eurodollar and Yankee dollar obligations, involve different investment risks than those affecting obligations of domestic banks, including, among others, the possibilities that: (i) their liquidity could be impaired because of political or economic developments; (ii) the obligations may be less marketable than comparable obligations of domestic banks; (iii) a foreign jurisdiction might impose withholding and other taxes at high levels on interest income; (iv) foreign deposits may be seized or nationalized; (v) foreign governmental restrictions such as exchange controls may be imposed, which could adversely affect the payment of principal or interest on those obligations; (vi) there may be less publicly available information concerning foreign banks issuing the obligations; and (vii) the reserve requirements and accounting, auditing and financial reporting standards, practices and requirements applicable to foreign banks may differ from those applicable to domestic banks. Foreign banks generally are not subject to examination by any U.S. Government agency or instrumentality.

Common Stock

Common stock represents a unit of equity ownership of a corporation. Owners typically are entitled to vote on the selection of directors and other important corporate governance matters, and to receive dividend payments, if any, on their holdings. However, ownership of common stock does not entitle owners to participate in the day-to-day operations of the corporation. Common stocks of domestic and foreign public corporations can be listed, and their shares traded, on domestic stock exchanges, such as the NYSE or the NASDAQ Stock Market. Domestic and foreign corporations also may have their shares traded on foreign exchanges, such as the London Stock Exchange or Tokyo Stock Exchange. Common stock may be privately placed or publicly offered. See Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Under normal conditions, the common stock investments of the Funds other than Columbia Thermostat Fund (as a percent of total assets) are allocated as follows:

	U.S. Companies Maximum	Foreign Companies Maximum
Fund
Columbia Acorn Fund	no limit	up to 33%
Columbia Acorn International	up to 25%	no limit
Columbia Acorn USA	no limit	up to 20%*
Columbia Acorn Select	no limit	up to 33%
Columbia International Select	up to 25%	no limit
Columbia Acorn European Fund	up to 10%	no limit
Columbia Acorn Emerging Markets Fund	up to 10%	no limit

* Not including securities represented by American Depositary Receipts.

Investing in common stocks is subject to certain risks. Stock market risk, for example, is the risk that the value of such stocks, like the broader stock markets, may decline or fail to rise over short or even extended periods of time, perhaps substantially or unexpectedly. Domestic and foreign stock markets tend to be cyclical, with periods when stock prices generally rise and periods when stock prices generally decline. The value of individual stocks will rise and fall based on factors specific to each company, such as changes in earnings or management, as well as general economic and market factors.

If a corporation is liquidated, the claims of secured and unsecured creditors and owners of debt securities and “preferred” stock take priority over the claims of those who own common stock.

Investing in common stocks also poses risks applicable to the particular type of company issuing the common stock. For example, stocks of smaller companies tend to have greater price swings than stocks of larger companies because, among other things, they trade less frequently and in lower volumes, are more susceptible to

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changes in economic conditions, may be more reliant on singular products or services and are more vulnerable to larger competitors. Common stocks of these types of companies may have a higher potential for gains, but also may be subject to greater risk of loss.

Investing in common stocks also poses risks applicable to a particular industry, such as technology, financial services, consumer goods or natural resources (e.g., oil and gas). To some extent, the prices of common stocks tend to move by industry sector. When market conditions favorably affect, or are expected to favorably affect, an industry, the share prices of the common stocks of companies in that industry tend to rise. Conversely, negative news or a poor outlook for a particular industry can cause the share prices of the common stocks of companies in that industry to decline quickly.

Convertible Securities

Convertible securities include bonds, debentures, notes, preferred stocks or other securities that may be converted or exchanged (by the holder or by the issuer) into shares of the underlying common stock (or cash or securities of equivalent value) at a stated exchange ratio or predetermined price (the conversion price). As such, convertible securities combine the investment characteristics of debt securities and equity securities. A holder of convertible securities is entitled to receive the income of a bond, debenture or note or the dividend of a preferred stock until the conversion privilege is exercised. The market value of convertible securities generally is a function of, among other factors, interest rates, the rates of return of similar nonconvertible securities and the financial strength of the issuer. The market value of convertible securities tends to decline as interest rates rise and, conversely, to rise as interest rates decline. However, a convertible security’s market value tends to reflect the market price of the common stock of the issuing company when that stock price approaches or is greater than its conversion price. As the market price of the underlying common stock declines, the price of the convertible security tends to be influenced more by the rate of return of the convertible security. Because both interest rate and market movements can influence their value, convertible securities generally are not as sensitive to changes in interest rates as similar debt securities nor generally are they as sensitive to changes in share price as their underlying common stock. Convertible securities may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind and step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Investing in convertible securities is subject to certain risks. Certain convertible securities, particularly securities that are convertible into securities of an issuer other than the issuer of the convertible security, may be illiquid and, therefore, may be more difficult to resell in a timely fashion or for a fair price, which could result in investment losses. Certain convertible securities may have a mandatory conversion feature, pursuant to which the securities convert automatically into common stock or other equity securities (of the same or a different issuer) at a specified date and a specified exchange ratio. Certain convertible securities may be convertible at the option of the issuer, which may require a holder to convert the security into the underlying common stock, even at times when the value of the underlying common stock or other equity security has declined substantially.

In addition, some convertible securities may be rated below investment grade or may not be rated and, therefore, may be considered speculative investments. Companies that issue convertible securities frequently are small- and mid-capitalization companies and, accordingly, carry the risks associated with such companies. In addition, the credit rating of a company’s convertible securities generally is lower than that of its conventional debt securities. Convertible securities are senior to equity securities and have a claim to the assets of an issuer prior to the holders of the issuer’s common stock in the event of liquidation but generally are subordinate to similar non-convertible debt securities of the same issuer. Some convertible securities are particularly sensitive to changes in interest rates when their predetermined conversion price is much higher than the price for the issuing company’s common stock.

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Corporate Debt Securities

Corporate debt securities are fixed income securities typically issued by businesses to finance their operations. Notes, bonds, debentures and commercial paper are the most common types of corporate debt securities, with the primary difference being their interest rates, maturity dates and secured or unsecured status. Commercial paper has the shortest term and usually is unsecured. The broad category of corporate debt securities includes debt issued by domestic or foreign companies of all kinds, including those with small-, mid- and large-capitalizations. The category also includes bank loans, as well as assignments, participations and other interests in bank loans. Corporate debt securities may be rated investment grade or below investment grade and may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Extendible commercial notes (ECNs) are very similar to commercial paper except that with ECNs, the issuer has the option to extend the notes’ maturity. ECNs are issued at a discount rate, with an initial redemption of not more than 90 days from the date of issue. If ECNs are not redeemed by the issuer on the initial redemption date, the issuer will pay a premium (step-up) rate based on the ECN’s credit rating at the time.

Because of the wide range of types and maturities of corporate debt securities, as well as the range of creditworthiness of issuers, corporate debt securities can have widely varying risk/return profiles. For example, commercial paper issued by a large established domestic corporation that is rated by an NRSRO as investment grade may have a relatively modest return on principal but present relatively limited risk. On the other hand, a long-term corporate note issued, for example, by a small foreign corporation from an emerging market country that has not been rated by an NRSRO may have the potential for relatively large returns on principal but carries a relatively high degree of risk.

Investing in corporate debt securities is subject to certain risks including, among others, credit and interest rate risk. Credit risk is the risk that a Fund could lose money if the issuer of a corporate debt security is unable to pay interest or repay principal when it becomes due. Some corporate debt securities that are rated below investment grade by an NRSRO generally are considered speculative because they present a greater risk of loss, including default, than higher quality debt securities. The credit risk of a particular issuer’s debt security may vary based on its priority for repayment. For example, higher ranking (senior) debt securities have a higher priority than and, therefore, may be paid in full before, lower ranking (subordinated) securities. In addition, in the event of bankruptcy, holders of higher-ranking senior securities may receive amounts otherwise payable to the holders of more junior securities. Interest rate risk is the risk that the value of certain corporate debt securities will tend to fall when interest rates rise. In general, corporate debt securities with longer terms tend to fall more in value when interest rates rise than do corporate debt securities with shorter terms.

Custody Receipts and Trust Certificates

Custody receipts and trust certificates are derivative products that evidence direct ownership in a pool of securities. Typically, a sponsor will deposit a pool of securities with a custodian in exchange for custody receipts evidencing interests in those securities. The sponsor generally then will sell the custody receipts or trust certificates in negotiated transactions at varying prices. Each custody receipt or trust certificate evidences the individual securities in the pool and the holder of a custody receipt or trust certificate generally will have all the rights and privileges of owners of those securities.

Investing in custody receipts and trust certificates is subject to certain risks. Custody receipts and trust certificates generally are subject to the same risks as the securities evidenced by the receipts or certificates. Custody receipts and trust certificates also may be less liquid than the underlying securities.

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Derivatives

General

Derivatives are financial instruments whose values are based on (or “derived” from) traditional securities (such as a stock or a bond), assets (such as a commodity, like gold), reference rates (such as LIBOR) or market indices (such as the S&P 500^® Index), or customized baskets of securities or instruments. Some forms of derivatives, such as exchange-traded futures and options on securities, commodities, or indices, are traded on regulated exchanges. These types of derivatives are standardized contracts that can easily be bought and sold, and whose market values are determined and published daily. Non-standardized derivatives, on the other hand, tend to be more specialized or complex, and may be harder to value. Derivatives afford leverage and, when used properly, can enhance returns and be useful in hedging portfolios. Some common types of derivatives include futures; options; options on futures; forward foreign currency exchange contracts; forward contracts on securities and securities indices; linked securities and structured products; CMOs; stripped securities; warrants; swap agreements and swaptions.

A Fund may use derivatives for a variety of reasons, including, for example: (i) to enhance its return; (ii) to attempt to protect against possible changes in the market value of securities held in or to be purchased for its portfolio resulting from securities markets or currency exchange rate fluctuations (i.e., to hedge); (iii) to protect its unrealized gains reflected in the value of its portfolio securities; (iv) to facilitate the sale of such securities for investment purposes; (v) to reduce transaction costs; and/or (vi) to manage the effective maturity or duration of its portfolio.

A Fund’s use of derivatives presents risks different from, and possibly greater than, the risks associated with investing directly in traditional securities. The use of derivatives can lead to losses because of adverse movements in the price or value of the underlying security, asset, index or reference rate, which may be magnified by certain features of the derivatives. These risks are heightened when a Fund uses derivatives to enhance its return or as a substitute for a position or security, rather than solely to hedge or offset the risk of a position or security held by a Fund. There is also a risk that the derivative will not correlate well with the security for which it is substituting. A Fund’s use of derivatives to leverage risk also may exaggerate a loss, potentially causing a Fund to lose more money than if it had invested in the underlying security, or limit a potential gain. The success of management’s derivative strategies will depend on its ability to assess and predict the impact of market or economic developments on the underlying security, asset, index or reference rate and the derivative itself, without necessarily the benefit of observing the performance of the derivative under all possible market conditions. Other risks arise from a Fund’s potential inability to terminate or sell its derivative positions as a liquid secondary market for such positions may not exist at times when a Fund may wish to terminate or sell them. Over-the-counter instruments (investments not traded on an exchange) may be illiquid. Derivatives traded in the over-the-counter market are subject to the risk that the other party will not meet its obligations. Also, with some derivative strategies there is the risk that a Fund may not be able to find a suitable derivative transaction counterparty, and thus may be unable to invest in derivatives altogether. The use of derivatives may also increase the amount and accelerate the timing of taxes payable by shareholders.

A Fund may use any or all of the above investment techniques and may purchase different types of derivative instruments at any time and in any combination. There is no particular strategy that dictates the use of one technique over another, as the use of derivatives is a function of numerous variables, including market conditions.

Index or Linked Securities (Structured Products)

General. Indexed or linked securities, also often referred to as “structured products,” are instruments that may have varying combinations of equity and debt characteristics. These instruments are structured to recast the investment characteristics of the underlying security or reference asset. If the issuer is a unit investment trust or other special purpose vehicle, the structuring will typically involve the deposit with or purchase by such issuer of specified instruments (such as commercial bank loans or securities) and/or the execution of various derivative transactions, and the issuance by that entity of one or more classes of securities (structured securities) backed by,

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or representing interests in, the underlying instruments. The cash flow on the underlying instruments may be apportioned among the newly issued structured securities to create securities with different investment characteristics, such as varying maturities, payment priorities and interest rate provisions, and the extent of such payments made with respect to structured securities is dependent on the extent of the cash flow on the underlying instruments.

Indexed and Inverse Floating Rate Securities. A Fund may invest in securities that provide a potential return based on a particular index of value or interest rates. For example, a Fund may invest in securities that pay interest based on an index of interest rates. The principal amount payable upon maturity of certain securities also may be based on the value of the index. To the extent a Fund invests in these types of securities, a Fund’s return on such securities will rise and fall with the value of the particular index: that is, if the value of the index falls, the value of the indexed securities owned by a Fund will fall. Interest and principal payable on certain securities may also be based on relative changes among particular indices.

A Fund may also invest in so-called “inverse floaters” or “residual interest bonds” on which the interest rates vary inversely with a floating rate (which may be reset periodically by a dutch auction, a remarketing agent, or by reference to a short-term tax-exempt interest rate index). A Fund may purchase synthetically-created inverse floating rate bonds evidenced by custodial or trust receipts. Generally, income on inverse floating rate bonds will decrease when interest rates increase, and will increase when interest rates decrease. Such securities have the effect of providing a degree of investment leverage, since they may increase or decrease in value in response to changes, as an illustration, in market interest rates at a rate that is a multiple of the rate at which fixed-rate securities increase or decrease in response to such changes. As a result, the market values of such securities will generally be more volatile than the market values of fixed-rate securities. To seek to limit the volatility of these securities, a Fund may purchase inverse floating obligations that have shorter-term maturities or that contain limitations on the extent to which the interest rate may vary. Certain investments in such obligations may be illiquid. A Fund may invest in indexed and inverse securities for hedging purposes or to seek to increase returns. When used for hedging purposes, indexed and inverse securities involve correlation risk. Furthermore, where such a security includes a contingent liability, in the event of an adverse movement in the underlying index or interest rate, a Fund may be required to pay substantial additional margin to maintain the position.

Credit-Linked Securities. Among the income producing securities in which a Fund may invest are credit- linked securities. The issuers of these securities frequently are limited purpose trusts or other special purpose vehicles that, in turn, invest in a derivative instrument or basket of derivative instruments, such as credit default swaps, interest rate swaps and other securities, in order to provide exposure to certain fixed income markets. For instance, a Fund may invest in credit-linked securities as a cash management tool in order to gain exposure to a certain market and/or to remain fully invested when more traditional income producing securities are not available.

Like an investment in a bond, investments in these credit-linked securities represent the right to receive periodic income payments (in the form of distributions) and payment of principal at the end of the term of the security. However, these payments are conditioned on or linked to the issuer’s receipt of payments from, and the issuer’s potential obligations to, the counterparties to the derivative instruments and other securities in which the issuer invests. For instance, the issuer may sell one or more credit default swaps, under which the issuer would receive a stream of payments over the term of the swap agreements provided that no event of default has occurred with respect to the referenced debt obligation upon which the swap is based. If a default occurs, the stream of payments may stop and the issuer would be obligated to pay the counterparty the par (or other agreed upon value) of the referenced debt obligation. This, in turn, would reduce the amount of income and/or principal that a Fund would receive. A Fund’s investments in these instruments are indirectly subject to the risks associated with derivative instruments, including, among others, credit risk, default or similar event risk, counterparty risk, interest rate risk, leverage risk and management risk. These securities generally are exempt from registration under the 1933 Act. Accordingly, there may be no established trading market for the securities and they may constitute illiquid investments.

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Index-, Commodity-, Currency- and Equity-Linked Securities. “Index-linked” or “commodity-linked” notes are debt securities of companies that call for interest payments and/or payment at maturity in different terms than the typical note where the borrower agrees to make fixed interest payments and to pay a fixed sum at maturity. Principal and/or interest payments on an index-linked or commodity-linked note depend on the performance of one or more market indices, such as the S&P 500^® Index, a weighted index of commodity futures such as crude oil, gasoline and natural gas or the market prices of a particular commodity or basket of commodities or securities. Equity-linked securities are short-term or intermediate term instruments having a value at maturity and/or interest rate determined by reference to the market prices of one or more equity securities. At maturity, the principal amount of an equity-linked debt security is often exchanged for common stock of the issuer or is payable in an amount based on the issuer’s common stock price at the time of maturity. Currency-linked debt securities are short-term or intermediate-term instruments having a value at maturity, and/or an interest rate, determined by reference to one or more foreign currencies. Payment of principal or periodic interest may be calculated as a multiple of the movement of one currency against another currency, or against an index.

Index, commodity, currency and equity-linked securities may entail substantial risks. Such instruments may be subject to significant price volatility. The company issuing the instrument may fail to pay the amount due on maturity. The underlying investment or security may not perform as expected by the Investment Manager. Markets, underlying securities and indexes may move in a direction that was not anticipated by the Investment Manager. Performance of the derivatives may be influenced by interest rate and other market changes in the United States and abroad, and certain derivative instruments may be illiquid.

Linked securities are often issued by unit investment trusts. Examples of this include such index-linked securities as S&P Depositary Receipts (SPDRs), which is an interest in a unit investment trust holding a portfolio of securities linked to the S&P 500^® Index, and a type of exchange traded fund (ETF). Because a unit investment trust is an investment company under the 1940 Act, a Fund’s investments in SPDRs are subject to the limitations set forth in Section 12(d)(1)(A) of the 1940 Act. SPDRs closely track the underlying portfolio of securities, trade like a share of common stock and pay periodic dividends proportionate to those paid by the portfolio of stocks that comprise the S&P 500^® Index. As a holder of interests in a unit investment trust, a Fund would indirectly bear its ratable share of that unit investment trust’s expenses. At the same time, a Fund would continue to pay its own management and advisory fees and other expenses, as a result of which a Fund and its shareholders in effect would be absorbing higher levels of fees with respect to investments in such unit investment trusts.

Equity-linked securities include issues such as Structured Yield Product Exchangeable for Stock (STRYPES), Trust Automatic Common Exchange Securities (TRACES), Trust Issued Mandatory Exchange Securities (TIMES), and Trust Enhanced Dividend Securities (TRENDS). The issuers of these equity-linked securities generally purchase and hold a portfolio of stripped U.S. Treasury securities maturing on a quarterly basis through the conversion date, and a forward purchase contract with an existing shareholder of the company relating to the common stock. Quarterly distributions on such equity-linked securities generally consist of the cash received from the U.S. Treasury securities and such equity-linked securities generally are not entitled to any dividends that may be declared on the common stock.

Investing in structured products and linked securities is subject to certain risks. Because structured products typically involve no credit enhancement, their credit risk generally will be equivalent to that of the underlying instruments. Investments in structured products may be structured as a class that is either subordinated or unsubordinated to the right of payment of another class. Subordinated structured products typically have higher rates of return and present greater risks than unsubordinated structured products. Structured products sometimes are sold in private placement transactions and often have a limited trading market.

Investments in “linked” securities have the potential to lead to significant losses because of unexpected movements in the underlying financial asset, index, currency or other investment. The ability of a Fund to utilize linked-securities successfully will depend on its ability correctly to predict pertinent market movements, which cannot be assured. Because currency-linked securities usually relate to foreign currencies, some of which may be currencies from emerging market countries, there are certain additional risks associated with such investments.

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SPDRs are subject to the risks of an investment in a broadly based portfolio of common stocks, including the risk that the general level of stock prices may decline, thereby adversely affecting the value of such investment. In addition, because individual investments in SPDRs are not redeemable, except upon termination of the unit investment trust, the liquidity of small holdings of SPDRs will depend upon the existence of a secondary market. Large holdings of SPDRs are called “creation unit size” and are redeemable in-kind only and are not redeemable for cash from the unit investment trust. The price of a SPDR is derived from and based upon the securities held by the unit investment trust. Accordingly, the level of risk involved in the purchase or sale of a SPDR is similar to the risk involved in the purchase or sale of traditional common stock, with the exception that the pricing mechanism for SPDRs is based on a basket of stocks. Disruptions in the markets for the securities underlying SPDRs purchased or sold by a Fund could result in losses on SPDRs.

Futures Contracts and Options on Futures Contracts

Futures Contracts. A futures contract sale creates an obligation by the seller to deliver the type of security or other asset called for in the contract at a specified delivery time for a stated price. A futures contract purchase creates an obligation by the purchaser to take delivery of the type of security or other asset called for in the contract at a specified delivery time for a stated price. The specific security or other asset delivered or taken at the settlement date is not determined until on or near that date. The determination is made in accordance with the rules of the exchange on which the futures contract was made. A Fund may enter into futures contracts which are traded on national or foreign futures exchanges and are standardized as to maturity date and underlying security or other asset. Futures exchanges and trading in the United States are regulated under the Commodity Exchange Act (CEA) by the Commodity Futures Trading Commission (CFTC), a U.S. Government agency.

Traders in futures contracts may be broadly classified as either “hedgers” or “speculators.” Hedgers use the futures markets primarily to offset unfavorable changes (anticipated or potential) in the value of securities or other assets currently owned or expected to be acquired by them. Speculators less often own the securities or other assets underlying the futures contracts which they trade, and generally use futures contracts with the expectation of realizing profits from fluctuations in the value of the underlying securities or other assets. Pursuant to a notice of eligibility claiming exclusion from the definition of commodity pool operator filed with the CFTC and the National Futures Association on behalf of the Funds, neither the Trust nor any of the individual Funds is deemed to be a “commodity pool operator” under the CEA, and, accordingly, they excluded from registration or regulation as such under the CEA. However, on February 9, 2012, the CFTC adopted amendments to its rules that, should they come into effect, may affect the ability of a Fund to continue to claim this exclusion. A Fund that seeks to claim the exclusion after the effectiveness of the amended rules would be limited in its ability to use futures and options on futures or commodities or engage in swap transactions. If a Fund were no longer able to claim the exclusion, the Investment Manager would be required to register as a “commodity pool operator,” and the Fund and the Investment Manager would be subject to regulation under the CEA.

Upon entering into futures contracts, in compliance with the SEC’s requirements, cash or liquid securities, equal in value to the amount of a Fund’s obligation under the contract (less any applicable margin deposits and any assets that constitute “cover” for such obligation), will be segregated with a Fund’s custodian.

Unlike when a Fund purchases or sells a security, no price is paid or received by a Fund upon the purchase or sale of a futures contract, although a Fund is required to deposit with its custodian in a segregated account in the name of the futures broker an amount of cash and/or U.S. Government securities in order to initiate and maintain open positions in futures contracts. This amount is known as “initial margin.” The nature of initial margin in futures transactions is different from that of margin in security transactions, in that futures contract margin does not involve the borrowing of funds by a Fund to finance the transactions. Rather, initial margin is in the nature of a performance bond or good faith deposit intended to assure completion of the contract (delivery or acceptance of the underlying security or other asset) that is returned to a Fund upon termination of the futures contract, assuming all contractual obligations have been satisfied. Minimum initial margin requirements are established by the relevant futures exchange and may be changed. Brokers may establish deposit requirements

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which are higher than the exchange minimums. Futures contracts are customarily purchased and sold on margin which may range upward from less than 5% of the value of the contract being traded. Subsequent payments, called “variation margin,” to and from the broker (or the custodian) are made on a daily basis as the price of the underlying security or other asset fluctuates, a process known as “marking to market.” If the futures contract price changes to the extent that the margin on deposit does not satisfy margin requirements, payment of additional variation margin will be required. Conversely, a change in the contract value may reduce the required margin, resulting in a repayment of excess margin to the contract holder. Variation margin payments are made for as long as the contract remains open. A Fund expects to earn interest income on its margin deposits.

Although futures contracts by their terms call for actual delivery or acceptance of securities or other assets (stock index futures contracts or futures contracts that reference other intangible assets do not permit delivery of the referenced assets), the contracts usually are closed out before the settlement date without the making or taking of delivery. A Fund may elect to close some or all of its futures positions at any time prior to their expiration. The purpose of taking such action would be to reduce or eliminate the position then currently held by a Fund. Closing out an open futures position is done by taking an opposite position (“buying” a contract which has previously been “sold,” “selling” a contract previously “purchased”) in an identical contract (i.e., the same aggregate amount of the specific type of security or other asset with the same delivery date) to terminate the position. Final determinations are made as to whether the price of the initial sale of the futures contract exceeds or is below the price of the offsetting purchase, or whether the purchase price exceeds or is below the offsetting sale price. Final determinations of variation margin are then made, additional cash is required to be paid by or released to a Fund, and a Fund realizes a loss or a gain. Brokerage commissions are incurred when a futures contract is bought or sold.

Successful use of futures contracts by a Fund is subject to the Investment Manager’s ability to predict correctly movements in the direction of interest rates and other factors affecting securities and commodities markets. This requires different skills and techniques than those required to predict changes in the prices of individual securities. A Fund, therefore, bears the risk that future market trends will be incorrectly predicted.

The risk of loss in trading futures contracts in some strategies can be substantial, due both to the relatively low margin deposits required and the potential for an extremely high degree of leverage involved in futures contracts. As a result, a relatively small price movement in a futures contract may result in an immediate and substantial loss to the investor. For example, if at the time of purchase, 10% of the value of the futures contract is deposited as margin, a subsequent 10% decrease in the value of the futures contract would result in a total loss of the margin deposit, before any deduction for the transaction costs, if the account were then closed out. A 15% decrease would result in a loss equal to 150% of the original margin deposit if the contract were closed out. Thus, a purchase or sale of a futures contract may result in losses in excess of the amount posted as initial margin for the contract.

In the event of adverse price movements, a Fund would continue to be required to make daily cash payments in order to maintain its required margin. In such a situation, if a Fund has insufficient cash, it may have to sell portfolio securities in order to meet daily margin requirements at a time when it may be disadvantageous to do so. The inability to close the futures position also could have an adverse impact on the ability to hedge effectively.

To reduce or eliminate a hedge position held by a Fund, a Fund may seek to close out a position. The ability to establish and close out positions will be subject to the development and maintenance of a liquid secondary market. It is not certain that this market will develop or continue to exist for a particular futures contract, which may limit a Fund’s ability to realize its profits or limit its losses. Reasons for the absence of a liquid secondary market on an exchange include the following: (i) there may be insufficient trading interest in certain contracts; (ii) restrictions may be imposed by an exchange on opening transactions, closing transactions or both; (iii) trading halts, suspensions or other restrictions may be imposed with respect to particular classes or series of contracts, or underlying securities; (iv) unusual or unforeseen circumstances, such as volume in excess of trading or clearing capability, may interrupt normal operations on an exchange; (v) the facilities of an exchange or a clearing corporation may not at all times be adequate to handle current trading volume; or (vi) one or more

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exchanges could, for economic or other reasons, decide or be compelled at some future date to discontinue the trading of contracts (or a particular class or series of contracts), in which event the secondary market on that exchange (or in the class or series of contracts) would cease to exist, although outstanding contracts on the exchange that had been issued by a clearing corporation as a result of trades on that exchange would continue to be exercisable in accordance with their terms.

Interest Rate Futures Contracts. Bond prices are established in both the cash market and the futures market. In the cash market, bonds are purchased and sold with payment for the full purchase price of the bond being made in cash, generally within five business days after the trade. In the futures market, a contract is made to purchase or sell a bond in the future for a set price on a certain date. Historically, the prices for bonds established in the futures markets have tended to move generally in the aggregate in concert with the cash market prices and have maintained fairly predictable relationships. Accordingly, a Fund may use interest rate futures contracts as a defense, or hedge, against anticipated interest rate changes. A Fund presently could accomplish a similar result to that which it hopes to achieve through the use of interest rate futures contracts by selling bonds with long maturities and investing in bonds with short maturities when interest rates are expected to increase, or conversely, selling bonds with short maturities and investing in bonds with long maturities when interest rates are expected to decline. However, because of the liquidity that is often available in the futures market, the protection is more likely to be achieved, perhaps at a lower cost and without changing the rate of interest being earned by a Fund, through using futures contracts.

Interest rate futures contracts are traded in an auction environment on the floors of several exchanges – principally, the Chicago Board of Trade, the Chicago Mercantile Exchange and the New York Futures Exchange. Each exchange guarantees performance under contract provisions through a clearing corporation, a nonprofit organization managed by the exchange membership. A public market exists in futures contracts covering various financial instruments including long term U.S. Treasury Bonds and Notes; GNMA modified pass-through mortgage backed securities; three-month U.S. Treasury Bills; and ninety-day commercial paper. A Fund may also invest in exchange-traded Eurodollar contracts, which are interest rate futures on the forward level of LIBOR. These contracts are generally considered liquid securities and trade on the Chicago Mercantile Exchange. Such Eurodollar contracts are generally used to “lock-in” or hedge the future level of short-term rates. A Fund may trade in any interest rate futures contracts for which there exists a public market, including, without limitation, the foregoing instruments.

Index Futures Contracts. An index futures contract is a contract to buy or sell units of an index at a specified future date at a price agreed upon when the contract is made. Entering into a contract to buy units of an index is commonly referred to as buying or purchasing a contract or holding a long position in the index. Entering into a contract to sell units of an index is commonly referred to as selling a contract or holding a short position in the index. A unit is the current value of the index. A Fund may enter into stock index futures contracts, debt index futures contracts, or other index futures contracts appropriate to its objective(s). A Fund may use index futures contracts for hedging or non-hedging purposes.

There are several risks in connection with the use by a Fund of index futures as a hedging device. One risk arises because of the imperfect correlation between movements in the prices of the index futures and movements in the prices of securities which are the subject of the hedges. The Investment Manager may attempt to reduce this risk by selling, to the extent possible, futures on indices the movements of which will, in its judgment, have a significant correlation with movements in the prices of a Fund’s portfolio securities sought to be hedged.

Options on Futures Contracts. A Fund may purchase and write call and put options on those futures contracts that it is permitted to buy or sell. A Fund may use such options on futures contracts in lieu of writing options directly on the underlying securities or other assets or purchasing and selling the underlying futures contracts. Such options generally operate in the same manner as options purchased or written directly on the underlying investments. A futures option gives the holder, in return for the premium paid, the right to buy from (call) or sell to (put) the writer of the option a futures contract at a specified price at any time during the period of

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the option. Upon exercise, the writer of the option is obligated to pay the difference between the cash value of the futures contract and the exercise price. Like the buyer or seller of a futures contract, the holder or writer of an option has the right to terminate its position prior to the scheduled expiration of the option by selling or purchasing an option of the same series, at which time the person entering into the closing purchase transaction will realize a gain or loss. There is no guarantee that such closing purchase transactions can be effected.

A Fund will enter into written options on futures contracts only when, in compliance with the SEC’s requirements, cash or liquid securities equal in value to the underlying security’s or other asset’s value (less any applicable margin deposits) have been deposited in a segregated account. A Fund will be required to deposit initial margin and maintenance margin with respect to put and call options on futures contracts written by it pursuant to brokers’ requirements similar to those described above.

Investments in futures options involve some of the same risks that are involved in connection with investments in futures contracts (for example, the existence of a liquid secondary market). In addition, the purchase of an option also entails the risk that changes in the value of the underlying futures contract will not be fully reflected in the value of the option purchased. There may be circumstances when the purchase of a call or put option on a futures contract would result in a loss to a Fund when the purchase or sale of a futures contract would not, such as when there is no movement in the prices of the hedged investments. In general, the market prices of options can be expected to be more volatile than the market prices on the underlying futures contracts. Compared to the purchase or sale of futures contracts, however, the purchase of call or put options on futures contracts may frequently involve less potential risk to a Fund because the maximum amount at risk is the premium paid for the options (plus transaction costs).

Successful use of index futures by a Fund is also subject to the Investment Manager’s ability to predict correctly movements in the direction of the market. It is possible that, for example, where a Fund has sold futures to hedge its portfolio against a decline in the market, the index on which the futures are written may advance and the value of securities held in a Fund’s portfolio may decline. If this occurred, a Fund would lose money on the futures and also experience a decline in the value of its portfolio securities, as a Fund’s ability to effectively hedge all or a portion of the securities in its portfolio, in anticipation of or during a market decline, through transactions in futures or put options on stock indices, depends on the degree to which price movements in the underlying index correlate with the price movements of the securities held by a Fund. Inasmuch as a Fund’s securities will not duplicate the components of an index, the correlation will not be perfect. Consequently, a Fund bears the risk that the prices of its securities being hedged will not move to the same extent as do the prices of its put options on the stock indices. It is also possible that, if a Fund has hedged against the possibility of a decline in the market adversely affecting securities held in its portfolio and securities prices increase instead, a Fund will lose part or all of the benefit of the increased values of those securities that it has hedged, because it will have offsetting losses in its futures positions. In addition, in such situations, if a Fund has insufficient cash, it may have to sell securities to meet daily variation margin requirements.

In addition to the possibility that there may be an imperfect correlation, or no correlation at all, between movements in the index futures and the securities of the portfolio being hedged, the prices of index futures may not correlate perfectly with movements in the underlying index due to certain market distortions. First, all participants in the futures markets are subject to margin deposit and maintenance requirements. Rather than meeting additional margin deposit requirements, investors may close futures contracts through offsetting transactions, which would distort the normal relationship between the index and futures markets. Second, margin requirements in the futures market are less onerous than margin requirements in the securities market, and as a result, the futures market may attract more speculators than the securities market. Increased participation by speculators in the futures market may also cause temporary price distortions. Due to the possibility of price distortions in the futures market, and also because of the imperfect correlation between movements in an index and movements in the prices of index futures, even a correct forecast of general market trends by the Investment Manager may still not result in a successful hedging transaction.

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There is also the risk of loss by a Fund of margin deposits in the event of bankruptcy of a broker with whom a Fund has an open position in a futures contract or related option. Most futures exchanges limit the amount of fluctuation permitted in some contract prices during a single trading day. The daily limit establishes the maximum amount that the price of a futures contract may vary either up or down from the previous day’s settlement price at the end of a trading session. Once the daily limit has been reached in a particular type of contract, no trades may be made on that day at a price beyond that limit. The daily limit governs only price movement during a particular trading day and, therefore, does not limit potential losses, because the limit may prevent the liquidation of unfavorable positions. Futures contract prices have occasionally moved to the daily limit for several consecutive trading days with little or no trading, thereby preventing prompt liquidation of futures positions and subjecting some futures traders to substantial losses.

Options on Index Futures Contracts. A Fund may also purchase and sell options on index futures contracts. Options on index futures give the purchaser the right, in return for the premium paid, to assume a position in an index futures contract (a long position if the option is a call and a short position if the option is a put), at a specified exercise price at any time during the period of the option. Upon exercise of the option, the delivery of the futures position by the writer of the option to the holder of the option will be accompanied by delivery of the accumulated balance in the writer’s futures margin account, which represents the amount by which the market price of the index futures contract, at exercise, exceeds (in the case of a call) or is less than (in the case of a put) the exercise price of the option on the index future. If an option is exercised on the last trading day prior to the expiration date of the option, the settlement will be made entirely in cash equal to the difference between the exercise price of the option and the closing level of the index on which the future is based on the expiration date. Purchasers of options who fail to exercise their options prior to the exercise date suffer a loss of the premium paid.

There are various risks in connection with the use by a Fund of index futures as a hedging device. For example, a risk arises because of the imperfect correlation between movements in the prices of the index futures and movements in the prices of securities which are the subject of the hedges. The Investment Manager will attempt to reduce this risk by selling, to the extent possible, futures on indices the movements of which will, in its judgment, have a significant correlation with movements in the prices of a Fund’s portfolio securities sought to be hedged; there can be no assurance that the Investment Manager will be successful in doing so.

Stock Options and Stock Index Options

A Fund may purchase and write (i.e., sell) put and call options. Such options may relate to particular stocks or stock indices, and may or may not be listed on a domestic or foreign securities exchange and may or may not be issued by the Options Clearing Corporation (OCC). Stock index options are put options and call options on various stock indices. In most respects, they are identical to listed options on common stocks.

There is a key difference between stock options and stock index options in connection with their exercise. In the case of stock options, the underlying security, common stock, is delivered. However, upon the exercise of an index option, settlement does not occur by delivery of the securities comprising the index. The option holder who exercises the index option receives an amount of cash if the closing level of the stock index upon which the option is based is greater than (in the case of a call) or less than (in the case of a put) the exercise price of the option. This amount of cash is equal to the difference between the closing price of the stock index and the exercise price of the option expressed in dollars times a specified multiple. A stock index fluctuates with changes in the market value of the securities included in the index. For example, some stock index options are based on a broad market index, such as the S&P 500^® Index or a narrower market index, such as the S&P 100^® Index. Indices may also be based on an industry or market segment.

The successful use of a Fund’s options strategies depends on the ability of the Investment Manager to forecast interest rate and market movements correctly. When it purchases an option, a Fund runs the risk that it will lose its entire investment in the option in a relatively short period of time, unless a Fund exercises the option

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or enters into a closing sale transaction for such option during the life of the option. If the price of the underlying security does not rise (in the case of a call) or fall (in the case of a put) to an extent sufficient to cover the option premium and transaction costs, a Fund will lose part or all of its investment in the option. This contrasts with an investment by a Fund in the underlying securities, since a Fund may continue to hold its investment in those securities notwithstanding the lack of a change in price of those securities.

The effective use of options also depends on a Fund’s ability to terminate option positions at times when the Investment Manager deems it desirable to do so. Although a Fund will take an option position only if the Investment Manager believes there is a liquid secondary market for the option, there is no assurance that a Fund will be able to effect closing transactions at any particular time or at an acceptable price.

If a secondary trading market in options were to become unavailable, a Fund could no longer engage in closing transactions. The writer in such circumstances would be subject to the risk of market decline or appreciation in the instrument during such period. If an option purchased by a Fund expires unexercised, a Fund will realize a loss equal to the premium paid. Reasons for the absence of a liquid secondary market on an exchange include the following: (i) there may be insufficient trading interest in certain options; (ii) restrictions may be imposed by an exchange on opening transactions or closing transactions or both; (iii) trading halts, suspensions or other restrictions may be imposed with respect to particular classes or series of options, or underlying securities; (iv) unusual or unforeseen circumstances, such as volume in excess of trading or clearing capability, may interrupt normal operations on an exchange; (v) the facilities of an exchange or a clearing corporation may not at all times be adequate to handle current trading volume; or (vi) one or more exchanges could, for economic or other reasons, decide or be compelled at some future date to discontinue the trading of options (or a particular class or series of options), in which event the secondary market on that exchange (or in the class or series of options) would cease to exist, although outstanding options on the exchange that had been issued by a clearing corporation as a result of trades on that exchange would continue to be exercisable in accordance with their terms.

Disruptions in the markets for the securities underlying options purchased or sold by a Fund could result in losses on the options. If trading is interrupted in an underlying security, the trading of options on that security is normally halted as well. As a result, a Fund as purchaser or writer of an option will be unable to close out its positions until options trading resumes, and it may be faced with losses if trading in the security reopens at a substantially different price. In addition, the OCC or other options markets may impose exercise restrictions. If a prohibition on exercise is imposed at a time when trading in the option has also been halted, a Fund as purchaser or writer of an option will be locked into its position until one of the two restrictions has been lifted. If a prohibition on exercise remains in effect until an option owned by a Fund has expired, a Fund could lose the entire value of its option.

Special risks are presented by internationally traded options. Because of time differences between the United States and various foreign countries, and because different holidays are observed in different countries, foreign options markets may be open for trading during hours or on days when U.S. markets are closed. As a result, option premiums may not reflect the current prices of the underlying interest in the United States.

Dealer (Over-the-Counter) Options. Dealer options are options negotiated individually through dealers rather than traded on an exchange. Certain risks are specific to dealer options. While a Fund might look to a clearing corporation to exercise exchange-traded options, if a Fund purchases a dealer option it must rely on the selling dealer to perform if a Fund exercises the option. Failure by the dealer to do so would result in the loss of the premium paid by a Fund as well as loss of the expected benefit of the transaction. Exchange-traded options generally have a continuous liquid market while dealer options more often may not. Consequently, a Fund can realize the value of a dealer option it has purchased only by exercising or reselling the option to the issuing dealer. Similarly, when a Fund writes a dealer option, a Fund can close out the option prior to its expiration only by entering into a closing purchase transaction with the dealer. While each Fund seeks to enter into dealer options only with dealers who will agree to and can enter into closing transactions with a Fund, no assurance exists that a Fund

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will at any time be able to liquidate a dealer option at a favorable price at any time prior to expiration. Unless a Fund, as a covered dealer call option writer, can effect a closing purchase transaction, it will not be able to liquidate securities (or other assets) used as cover until the option expires or is exercised. In the event of insolvency of the other party, a Fund may be unable to liquidate a dealer option. With respect to options written by a Fund, the inability to enter into a closing transaction may result in material losses to a Fund. For example, because a Fund must maintain a secured position with respect to any call option on a security it writes, a Fund may not sell the assets that it has segregated to secure the position while it is obligated under the option. This requirement may impair a Fund’s ability to sell portfolio securities at a time when such sale might be advantageous.

A Fund generally will treat purchased dealer options as illiquid securities. A Fund may treat the cover used for written dealer options as liquid if the dealer agrees that a Fund may repurchase the dealer option it has written for a maximum price to be calculated by a predetermined formula. In such cases, the dealer option would be considered illiquid only to the extent the maximum purchase price under the formula exceeds the intrinsic value of the option.

Writing Covered Options. A Fund may write covered call options and covered put options on securities held in its portfolio when, in the opinion of the Investment Manager, such transactions are consistent with a Fund’s investment goal and policies. Call options written by a Fund give the purchaser the right to buy the underlying securities from a Fund at the stated exercise price at any time prior to the expiration date of the option, regardless of the security’s market price; put options give the purchaser the right to sell the underlying securities to a Fund at the stated exercise price at any time prior to the expiration date of the option, regardless of the security’s market price.

A Fund may write only covered options, which means that, so long as a Fund is obligated as the writer of a call option, it will own the underlying securities subject to the option (or comparable securities satisfying the cover requirements of securities exchanges). In the case of put options, a Fund will hold cash and/or high-grade short-term debt obligations equal to the price to be paid if the option is exercised. In addition, a Fund will be considered to have covered a put or call option if and to the extent that it holds an option that offsets some or all of the risk of the option it has written. A Fund may write combinations of covered puts and calls (straddles) on the same underlying security.

A Fund will receive a premium from writing a put or call option, which increases a Fund’s return on the underlying security if the option expires unexercised or is closed out at a profit. The amount of the premium reflects, among other things, the relationship between the exercise price and the current market value of the underlying security, the volatility of the underlying security, the amount of time remaining until expiration, current interest rates, and the effect of supply and demand in the options market and in the market for the underlying security. By writing a call option, a Fund limits its opportunity to profit from any increase in the market value of the underlying security above the exercise price of the option but continues to bear the risk of a decline in the value of the underlying security. By writing a put option, a Fund assumes the risk that it may be required to purchase the underlying security for an exercise price higher than the security’s then-current market value, resulting in a potential capital loss unless the security subsequently appreciates in value.

A Fund’s obligation to sell an instrument subject to a call option written by it, or to purchase an instrument subject to a put option written by it, may be terminated prior to the expiration date of the option by a Fund’s execution of a closing purchase transaction, which is effected by purchasing on an exchange an offsetting option of the same series (i.e., same underlying instrument, exercise price and expiration date) as the option previously written. A closing purchase transaction will ordinarily be effected in order to realize a profit on an outstanding option, to prevent an underlying instrument from being called, to permit the sale of the underlying instrument or to permit the writing of a new option containing different terms on such underlying instrument. A Fund realizes a profit or loss from a closing purchase transaction if the cost of the transaction (option premium plus transaction costs) is less or more than the premium received from writing the option. Because increases in the market price of a call option generally reflect increases in the market price of the security underlying the option, any loss resulting from a closing purchase transaction may be offset in whole or in part by unrealized appreciation of the underlying security.

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If a Fund writes a call option but does not own the underlying security, and when it writes a put option, a Fund may be required to deposit cash or securities with its broker as “margin” or collateral for its obligation to buy or sell the underlying security. As the value of the underlying security varies, a Fund may also have to deposit additional margin with the broker. Margin requirements are complex and are fixed by individual brokers, subject to minimum requirements currently imposed by the Federal Reserve Board and by stock exchanges and other self-regulatory organizations.

Purchasing Put Options. A Fund may purchase put options to protect its portfolio holdings in an underlying security against a decline in market value. Such hedge protection is provided during the life of the put option since a Fund, as holder of the put option, is able to sell the underlying security at the put exercise price regardless of any decline in the underlying security’s market price. For a put option to be profitable, the market price of the underlying security must decline sufficiently below the exercise price to cover the premium and transaction costs. By using put options in this manner, a Fund will reduce any profit it might otherwise have realized from appreciation of the underlying security by the premium paid for the put option and by transaction costs.

Purchasing Call Options. A Fund may purchase call options to hedge against an increase in the price of securities that a Fund wants ultimately to buy. Such hedge protection is provided during the life of the call option since a Fund, as holder of the call option, is able to buy the underlying security at the exercise price regardless of any increase in the underlying security’s market price. In order for a call option to be profitable, the market price of the underlying security must rise sufficiently above the exercise price to cover the premium and transaction costs. These costs will reduce any profit a Fund might have realized had it bought the underlying security at the time it purchased the call option.

Over-the-Counter (OTC) Options. A Fund will enter into OTC options transactions only with primary dealers in U.S. Government securities and, in the case of OTC options written by a Fund, only pursuant to agreements that will assure that a Fund will at all times have the right to repurchase the option written by it from the dealer at a specified formula price. A Fund will treat the amount by which such formula price exceeds the amount, if any, by which the option may be “in-the-money” as an illiquid investment. It is the present policy of a Fund not to enter into any OTC option transaction if, as a result, more than 15% (10% in some cases, refer to a Fund’s prospectuses) of a Fund’s net assets would be invested in (i) illiquid investments (determined under the foregoing formula) relating to OTC options written by a Fund, (ii) OTC options purchased by a Fund, (iii) securities which are not readily marketable, and (iv) repurchase agreements maturing in more than seven days.

Index Options. As an alternative to purchasing call and put options on index futures, a Fund may purchase call and put options on the underlying indices themselves. Such options could be used in a manner identical to the use of options on index futures. Options involving securities indices provide the holder with the right to make or receive a cash settlement upon exercise of the option based on movements in the relevant index. Such options must be listed on a national securities exchange and issued by the OCC. Such options may relate to particular securities or to various stock indices, except that a Fund may not write covered options on an index.

Foreign Stock Index Options. A Fund may, for the purpose of hedging its portfolio, subject to applicable securities regulations, purchase and write put and call options on foreign stock indices listed on foreign and domestic stock exchanges.

Swap Agreements

Swap agreements are derivative instruments that can be individually negotiated and structured to include exposure to a variety of different types of investments or market factors. Depending on their structure, swap agreements may increase or decrease a Fund’s exposure to long- or short-term interest rates, foreign currency values, mortgage securities, corporate borrowing rates, or other factors such as security prices or inflation rates. A Fund may enter into a variety of swap agreements, including interest rate, index, inflation index commodity, equity, credit default and currency exchange rate swap agreements, and other types of swap agreements such as caps, collars and floors. A Fund also may enter into swaptions, which are options to enter into a swap agreement.

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In a typical interest rate swap, one party agrees to make regular payments equal to a floating interest rate times a “notional principal amount,” in return for payments equal to a fixed rate times the same amount, for a specified period of time. If a swap agreement provides for payments in different currencies, the parties might agree to exchange notional principal amount as well. In a total return swap agreement, the non-floating rate side of the swap is based on the total return of an individual security, a basket of securities, an index or another reference asset. Swaps may also depend on other prices or rates, such as the value of an index or mortgage prepayment rates.

In a typical cap or floor agreement, one party agrees to make payments only under specified circumstances, usually in return for payment of a fee by the other party. For example, the buyer of an interest rate cap obtains the right to receive payments to the extent that a specified interest rate exceeds an agreed-upon level, while the seller of an interest rate floor is obligated to make payments to the extent that a specified interest rate falls below an agreed-upon level. Caps and floors have an effect similar to buying or writing options. A collar combines elements of buying a cap and selling a floor.

Swap agreements will tend to shift a Fund’s investment exposure from one type of investment to another. For example, if a Fund agreed to pay fixed rates in exchange for floating rates while holding fixed-rate bonds, the swap would tend to decrease a Fund’s exposure to long-term interest rates. Another example is if a Fund agreed to exchange payments in dollars for payments in foreign currency, the swap agreement would tend to decrease a Fund’s exposure to U.S. interest rates and increase its exposure to foreign currency and interest rates.

Swap agreements are sophisticated hedging instruments that typically involve a small investment of cash relative to the magnitude of risks assumed. As a result, swaps can be highly volatile and may have a considerable impact on a Fund’s performance. Depending on how they are used, swap agreements may increase or decrease the overall volatility of a Fund’s investments and its share price and yield. Additionally, whether a Fund’s use of swap agreements will be successful in furthering its investment objective will depend on the Investment Manager’s ability correctly to predict whether certain types of investments are likely to produce greater returns than other investments. Because they are two party contracts and because they may have terms of greater than seven days, swap agreements may be considered to be illiquid. Moreover, a Fund bears the risk of loss of the amount expected to be received under a swap agreement in the event of the default or bankruptcy of a swap agreement counterparty. The most significant factor in the performance of swap agreements is the change in the specific interest rate, currency, or other factor that determines the amounts of payments due to and from a Fund. If a swap agreement calls for payments by a Fund, a Fund must be prepared to make such payments when due. In addition, if the counterparty’s creditworthiness declines, the value of a swap agreement likely would decline, potentially resulting in losses for a Fund. A Fund will closely monitor the credit of a swap agreement counterparty in order to attempt to minimize this risk. A Fund may also suffer losses if it is unable to terminate outstanding swap agreements (either by assignment or other disposition) or reduce its exposure through offsetting transactions (i.e., by entering into an offsetting swap agreement with the same party or a similarly creditworthy party).

Credit Default Swap Agreements. A Fund may enter into credit default swap agreements, which may have as reference obligations one or more securities or a basket of securities that are or are not currently held by a Fund. The protection “buyer” in a credit default contract is generally obligated to pay the protection “seller” an upfront or a periodic stream of payments over the term of the contract provided that no credit event, such as a default, on a reference obligation has occurred. If a credit event occurs, the seller generally must pay the buyer the “par value” (full notional value) of the swap in exchange for an equal face amount of deliverable obligations of the reference entity described in the swap, or the seller may be required to deliver the related net cash amount, if the swap is cash settled. A Fund may be either the buyer or seller in the transaction. If a Fund is a buyer and no credit event occurs, a Fund may recover nothing if the swap is held through its termination date. However, if a credit event occurs, the buyer generally may elect to receive the full notional value of the swap in exchange for an equal face amount of deliverable obligations of the reference entity whose value may have significantly decreased. As a seller, a Fund generally receives an upfront payment or a fixed rate of income throughout the

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term of the swap provided that there is no credit event. As the seller, a Fund would effectively add leverage to its portfolio because, in addition to its total net assets, a Fund would be subject to investment exposure on the notional amount of the swap.

Credit default swap agreements may involve greater risks than if a Fund had invested in the reference obligation directly since, in addition to risks relating to the reference obligation, credit default swaps are subject to illiquidity risk, counterparty risk and credit risk. A Fund will enter into credit default swap agreements generally with counterparties that meet certain standards of creditworthiness. A buyer generally will lose its investment and recover nothing if no credit event occurs and the swap is held to its termination date. If a credit event were to occur, the value of any deliverable obligation received by the seller, coupled with the upfront or periodic payments previously received, may be less than the full notional value it pays to the buyer, resulting in a loss of value to the seller.

Equity Swaps. A Fund may engage in equity swaps. Equity swaps allow the parties to the swap agreement to exchange components of return on one equity investment (e.g., a basket of equity securities or an index) for a component of return on another non-equity or equity investment, including an exchange of differential rates of return. Equity swaps may be used to invest in a market without owning or taking physical custody of securities in circumstances where direct investment may be restricted for legal reasons or is otherwise impractical. Equity swaps also may be used for other purposes, such as hedging or seeking to increase total return.

The values of equity swaps can be very volatile. To the extent that the Investment Manager does not accurately analyze and predict the potential relative fluctuation on the components swapped with the other party, a Fund may suffer a loss. The value of some components of an equity swap (such as the dividend on a common stock) may also be sensitive to changes in interest rates. Furthermore, during the period a swap is outstanding, a Fund may suffer a loss if the counterparty defaults.

Total Return Swap Agreements. Total return swap agreements are contracts in which one party agrees to make periodic payments to another party based on the change in market value of the assets underlying the contract, which may include a specified security, basket of securities or securities indices during the specified period, in return for periodic payments based on a fixed or variable interest rate or the total return from other underlying assets. Total return swap agreements may be used to obtain exposure to a security or market without owning or taking physical custody of such security or investing directly in such market. Total return swap agreements may effectively add leverage to a Fund’s portfolio because, in addition to its total net assets, a Fund would be subject to investment exposure on the notional amount of the swap.

Total return swap agreements are subject to the risk that a counterparty will default on its payment obligations to a Fund thereunder, and conversely, that a Fund will not be able to meet its obligation to the counterparty. Generally, a Fund will enter into total return swaps on a net basis (i.e., the two payment streams are netted against one another with a Fund receiving or paying, as the case may be, only the net amount of the two payments). The net amount of the excess, if any, of a Fund’s obligations over its entitlements with respect to each total return swap will be accrued on a daily basis, and an amount of liquid assets having an aggregate net asset value (NAV) at least equal to the accrued excess will be segregated by a Fund. If the total return swap transaction is entered into on other than a net basis, the full amount of a Fund’s obligations will be accrued on a daily basis, and the full amount of a Fund’s obligations will be segregated by a Fund in an amount equal to or greater than the market value of the liabilities under the total return swap agreement or the amount it would have cost a Fund initially to make an equivalent direct investment, plus or minus any amount a Fund is obligated to pay or is to receive under the total return swap agreement.

Variance, Volatility and Correlation Swap Agreements. Variance and volatility swaps are contracts that provide exposure to increases or decreases in the volatility of certain referenced assets. Correlation swaps are contracts that provide exposure to increases or decreases in the correlation between the prices of different assets or different market rates.

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Dollar Rolls

Dollar rolls involve selling securities (e.g., mortgage-backed securities or U.S. Treasury securities) and simultaneously entering into a commitment to purchase those or similar (same collateral type, coupon and maturity) securities on a specified future date and price. Mortgage dollar rolls and U.S. Treasury rolls are types of dollar rolls. A Fund foregoes principal and interest paid on the securities during the “roll” period. A Fund is compensated by the difference between the current sales price and the lower forward price for the future purchase of the securities as well as the interest earned on the cash proceeds of the initial sale.

Dollar rolls involve the risk that the market value of the securities a Fund is obligated to repurchase may decline below the repurchase price or that the transaction costs may exceed the return earned by a Fund from the transaction. Dollar rolls also involve risk to a Fund if the other party should default on its obligation and a Fund is delayed or prevented from completing the transaction. In the event that the buyer of securities under a dollar roll files for bankruptcy or becomes insolvent, a Fund’s use of proceeds of the dollar roll may be restricted pending a determination by the other party, or its trustee or receiver, whether to enforce a Fund’s obligation to repurchase the securities. In addition, the security to be delivered in the future may turn out to be inferior to the security sold upon entering into the transaction.

Foreign Currency Transactions

Foreign currency transactions may be used to protect, to some extent, against uncertainty in the level of future currency exchange rates by establishing a fixed exchange rate. Foreign currency transactions may involve the purchase or sale of foreign currencies on a “spot” (cash) basis at the prevailing exchange rate or may involve “forward contracts” that allow a Fund to purchase or sell foreign currencies at a future date. The Funds may purchase and sell certain foreign currency forward contracts designed to align the Funds more closely with the foreign currency exposures of their primary benchmarks, without the necessity of changes to their equity portfolios. The Funds do not, however, typically engage in hedging of foreign currency risk against the U.S. dollar, though the portfolio manager is not precluded from employing that strategy. Forward contracts may be used for “transaction hedging,” “position hedging” and “cross-hedging.” A Fund may use forward sale contracts to sell an amount of a foreign currency approximating the value of a Fund’s securities denominated in the foreign security when that foreign currency suffers a substantial decline against the U.S. dollar. A Fund may use forward purchase contracts to purchase a foreign currency when it is believed that the U.S. dollar may suffer a substantial decline against the foreign currency. A Fund may use forward contracts to buy or sell a foreign currency or U.S. dollars when the Investment Manager believes it has exposure to a foreign currency or U.S. dollars which may suffer or enjoy a movement against another foreign currency to which the Fund has exposure or the U.S. dollar. Although these transactions tend to minimize the risk of loss due to a decline in the value of the hedged currency, they also tend to limit any potential gain that might be realized if the value of the hedged currency increases.

Transaction hedging may allow a Fund to “lock in” the U.S. dollar price of a security it has agreed to purchase or sell, or the U.S. dollar equivalent of a dividend or interest rate payment in a foreign currency. A Fund may use transaction hedging to protect itself against a possible loss resulting from an adverse change in the relationship between the U.S. dollar and the applicable foreign currency during the period between the date on which the security is purchased or sold, or on which the dividend or interest payment is declared, and the date on which such payments are made or received.

Position hedging may allow a Fund to protect against an adverse change in the relationship between the U.S. dollar and the applicable foreign currencies in which its portfolio securities are denominated. A Fund may use position hedging when it is believed that the U.S. dollar may suffer a decline against the foreign currency by entering into a forward purchase contract to purchase a currency in which a portfolio position of the Fund is denominated or by purchasing a currency in which the Fund anticipates acquiring a portfolio position for a fixed dollar amount. A Fund will not attempt to hedge all of its foreign portfolio positions.

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Cross-hedging may allow a Fund to enter into a forward contract to sell a different foreign currency for a fixed U.S. dollar amount when it is believed that the U.S. dollar value of the currency to be sold pursuant to the forward contract will fall if there is a decline in the U.S. dollar value of the currency in which a Fund’s securities are denominated.

A Fund also may purchase exchange-listed and over-the-counter call and put options on foreign currencies and foreign currency contracts. Options on foreign currencies and foreign currency contracts give the holder a right to buy or sell the underlying foreign currencies or foreign currency contracts for a specified period of time and for a specified amount. The value of an option on foreign currencies or foreign currency contracts reflects the value of an exchange rate, which depends on the relative values of the U.S. dollar and the relevant foreign currency.

Engaging in foreign currency transactions is subject to certain risks. For example, if the value of a foreign currency were to decline against the U.S. dollar, such decline would reduce the dollar value of any securities held by a Fund denominated in that currency. It is impossible to forecast with precision the market value of portfolio securities at the expiration or maturity of a forward or futures contract, which may make it necessary for a Fund to purchase additional foreign currency on the spot market if the market value of the security being hedged is less than the amount of foreign currency a Fund is obligated to deliver at the time a Fund sells the security being hedged. The value of any currency, including the U.S. dollar, may be affected by political and economic factors applicable to the issuer’s country. The exchange rates of currencies also may be affected adversely by governmental actions. Transaction, position and cross-hedging do not eliminate fluctuations in the underlying prices of securities that a Fund owns or intends to purchase or sell and may limit the amount of potential gain that might result from the increase in value of the currency being hedged. Settlement procedures relating to a Fund’s foreign currency transactions may be more complex than those relating to investments in securities of U.S. issuers.

Foreign Securities

Foreign securities include debt, equity and derivative securities that the Investment Manager determines are “foreign” based on the consideration of an issuer’s domicile, its principal place of business, its primary stock exchange listing, the source of its revenue, the location of its assets, its exposure to the economic fortunes and risks of countries or geographic regions outside the United States, or other factors. Foreign securities may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Foreign securities may include depositary receipts, such as American Depositary Receipts (ADRs), European Depositary Receipts (EDRs) and Global Depositary Receipts (GDRs). ADRs are U.S. dollar-denominated receipts issued in registered form by a domestic bank or trust company that evidence ownership of underlying securities issued by a foreign issuer. EDRs are foreign currency-denominated receipts issued in Europe, typically by foreign banks or trust companies and foreign branches of domestic banks, that evidence ownership of foreign or domestic securities. GDRs are receipts structured similarly to ADRs and EDRs and are marketed globally. Depositary receipts will not necessarily be denominated in the same currency as their underlying securities. In general, ADRs, in registered form, are designed for use in the U.S. securities markets, and EDRs, in bearer form, are designed for use in European securities markets. GDRs are tradable both in the United States and in Europe and are designed for use throughout the world. A Fund may invest in depositary receipts through “sponsored” or “unsponsored” facilities. A sponsored facility is established jointly by the issuer of the underlying security and a depositary, whereas a depositary may establish an unsponsored facility without participation by the issuer of the deposited security. Holders of unsponsored depositary receipts generally bear all the costs of such facilities and the depositary of an unsponsored facility frequently is under no obligation to distribute interestholder communications received from the issuer of the deposited security or to pass through voting rights to the holders of such receipts in respect of the deposited securities. The issuers of unsponsored

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depositary receipts are not obligated to disclose material information in the United States, and, therefore, there may be limited information available regarding such issuers and/or limited correlation between available information and the market value of the depositary receipts.

Due to the potential for foreign withholding taxes, Morgan Stanley Capital International (MSCI) publishes two versions of its indices reflecting the reinvestment of dividends using two different methodologies: gross dividends and net dividends. While both versions reflect reinvested dividends, they differ with respect to the manner in which taxes associated with dividend payments are treated. In calculating the net dividends version, MSCI incorporates reinvested dividends applying the withholding tax rate applicable to foreign non-resident institutional investors that do not benefit from double taxation treaties. The Investment Manager believes that the net dividends version of MSCI indices better reflects the returns U.S. investors might expect were they to invest directly in the component securities of an MSCI index.

Investing in foreign securities is subject to certain risks. For example, foreign markets can be extremely volatile. Fluctuations in currency exchange rates also may impact the value of foreign securities denominated in foreign currencies or U.S. dollars, without a change in the intrinsic value of those securities. Additionally, the U.S. dollar value of a foreign security tends to decrease when the value of the U.S. dollar rises against the foreign currency in which the security is denominated and tends to increase when the value of the U.S. dollar falls against such currency. A Fund may attempt to minimize the risk from adverse changes in the relationship between the U.S. dollar and foreign currencies by purchasing and selling forward foreign currency exchange contracts and foreign currency futures contracts and related options. Foreign securities may be less liquid than domestic securities so that a Fund may, at times, be unable to sell foreign securities at desirable prices. Brokerage commissions, custodial fees and other fees also are generally higher for foreign securities. A Fund may have limited legal recourse in the event of default with respect to certain debt securities issued by foreign governments. Foreign governments may impose potentially confiscatory withholding or other taxes, which would reduce a Fund’s return on these securities. There is generally less publicly available information about foreign companies. Investments in foreign companies may be adversely affected by the impact of political, social or diplomatic events or possible seizure, expropriation or nationalization of a company or its assets resulting in a partial or total loss of an investment in such foreign companies. Accounting, auditing and financial reporting standards may also be less comprehensive and stringent than those applicable to domestic companies.

Operational and Settlement Risks of Foreign Securities. A Fund’s foreign securities are generally held outside the United States in the primary market for the securities in the custody of certain eligible foreign banks and trust companies, as permitted under the 1940 Act (“foreign sub-custodians”). Settlement practices for foreign securities may differ from those in the United States. Some countries have limited governmental oversight and regulation of industry practices, stock exchanges, depositories, registrars, brokers and listed companies, which increases the risk of corruption and fraud and the possibility of losses to a Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that the Fund may be required to make payment for securities before the Fund has actually received delivery of the securities or deliver securities prior to the receipt of payment. Typically, in these cases, the Fund will receive evidence of ownership in accordance with the generally accepted settlement practices in the local market entitling the Fund to delivery or payment at a future date, but there is a risk that the security will not be delivered to the Fund or that payment will not be received, although the Fund and its foreign sub-custodians take reasonable precautions to mitigate this risk. Losses can also result from lost, stolen or counterfeit securities; defaults by brokers and banks; failures or defects of the settlement system; or poor and improper record keeping by registrars and issuers.

Share Blocking. Share blocking refers to a practice in certain foreign markets under which an issuer’s securities are blocked from trading at the custodian or sub-custodian level for a specified number of days before and, in certain instances, after a shareholder meeting where a vote of shareholders takes place. The blocking period can last up to several weeks. Share blocking may prevent a Fund from buying or selling securities during this period, because during the time shares are blocked, trades in such securities will not settle. It may be difficult or impossible to lift blocking restrictions, with the particular requirements varying widely by country. As a consequence of these restrictions, the Investment Manager, on behalf of a Fund, may abstain from voting proxies in markets that require share blocking.

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Emerging Market Securities. Risks associated with investments in foreign securities are increased with respect to investments in emerging market countries. Political and economic structures in many emerging market countries, especially Russia and those in Eastern Europe, the Middle East, Asia, Latin America and Africa, are undergoing significant evolutionary changes and rapid development, and may lack the social, political and economic stability of more developed countries. Investing in emerging market securities also involves risks beyond the risks applicable to foreign investments.

Operational and Settlement Risks of Securities in Emerging Markets. In addition to having less developed securities markets, banks in emerging markets that are eligible foreign sub-custodians may be recently organized, lack extensive operating experience or lack effective government oversight or regulation. In addition, there may be legal restrictions or limitations on the ability of a Fund to recover assets held in custody by a foreign sub-custodian in the event of the bankruptcy of the sub-custodian. Because settlement systems may be less organized than in developed markets and because delivery versus payment settlement may not be possible or reliable, there may be a greater risk that settlement may be delayed and that cash or securities of a Fund may be lost because of failures of or defects in the system, including fraud or corruption. Settlement systems in emerging markets also have a higher risk of failed trades. Ownership of Russian securities poses particular risks because ownership records are typically maintained in a decentralized fashion by registrars who may not be subject to effective governmental supervision leading to the possibility that a Fund may lose its ownership rights. In such a case, it may be difficult for a Fund to enforce any rights it may have against the registrar or issuer of the securities.

Risks Related to Currencies and Corporate Actions in Emerging Markets. Risks related to currencies and corporate actions are also greater in emerging market countries than in developed countries. For example, some emerging market countries may have fixed or managed currencies that are not free-floating against the U.S. dollar. Further, certain currencies may not be traded internationally, or countries may have varying exchange rates. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience sustained periods of high inflation or rapid changes in inflation rates which can have negative effects on a country’s economy and securities markets. Corporate action procedures in emerging market countries may be less reliable and have limited or no involvement by the depositories and central banks. Lack of standard practices and payment systems can lead to significant delays in payment.

Risks Related to Corporate and Securities Laws in Emerging Markets. Securities laws in emerging markets may be relatively new and unsettled and, consequently, there is a risk of rapid and unpredictable change in laws regarding foreign investment, securities regulation, title to securities and shareholder rights. Accordingly, foreign investors may be adversely affected by new or amended laws and regulations. In addition, the systems of corporate governance to which issuers in certain emerging markets are subject may be less advanced than the systems to which issuers located in more developed countries are subject, and therefore, shareholders of such issuers may not receive many of the protections available to shareholders of issuers located in more developed countries. These risks may be heightened in certain countries, including, without limitation, Russia.

Under normal conditions, the Funds’ investments in foreign companies (as a percent of total assets) are allocated as follows:

Fund	Total	Developed Countries	Emerging Markets
Columbia Acorn Fund	up to 33%	no additional limit	no additional limit
Columbia Acorn International	at least 75%	no limit	no limit
Columbia Acorn USA	up to 20%*	no additional limit	no additional limit
Columbia Acorn Select	up to 33%	no additional limit	no additional limit
Columbia Acorn International Select	at least 75%	at least 65%	up to 35%
Columbia Acorn European Fund	at least 80%	at least 70%	up to 30%
Columbia Acorn Emerging Markets Fund	at least 80%	up to 20%	at least 80%
Columbia Thermostat Fund	N/A**	N/A**	N/A**

* Not including securities represented by American Depositary Receipts.

** Certain of the Portfolio Funds may invest in foreign companies. Refer to the Portfolio Funds’ investment policies, as set forth in their respective statements of additional information, which are available at www.columbiamanagement.com and www.sec.gov.

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Guaranteed Investment Contracts (Funding Agreements)

Guaranteed investment contracts, or funding agreements, are debt instruments issued by insurance companies. Pursuant to such contracts, a Fund may make cash contributions to a deposit fund of the insurance company’s general account. The insurance company then credits to a Fund payments at negotiated, floating or fixed interest rates. A Fund will purchase guaranteed investment contracts only from issuers that, at the time of purchase, meet certain credit and quality standards.

Investing in guaranteed investment contracts is subject to certain risks. In general, guaranteed investment contracts are not assignable or transferable without the permission of the issuing insurance companies, and an active secondary market does not exist for these investments. In addition, the issuer may not be able to pay the principal amount to a Fund on seven days notice or less, at which time the investment may be considered illiquid under applicable SEC regulatory guidance and subject to certain restrictions.

Illiquid Securities

Illiquid securities are defined by a Fund consistent with the SEC staff’s current guidance and interpretations which provide that an illiquid security is an asset which may not be sold or disposed of in the ordinary course of business within seven days at approximately the value at which a Fund has valued the investment on its books. Some securities, such as those not registered under U.S. securities laws, cannot be sold in public transactions. Subject to its investment policies, a Fund may invest in illiquid investments and may invest in certain restricted securities that are deemed to be illiquid securities.

Initial Public Offerings

A Fund may invest in initial public offerings (IPOs) of common stock or other primary or secondary syndicated offerings of equity or debt securities issued by a corporate issuer. A purchase of IPO securities often involves higher transaction costs than those associated with the purchase of securities already traded on exchanges or markets. IPO securities are subject to market risk and liquidity risk. The market value of recently issued IPO securities may fluctuate considerably due to factors such as the absence of a prior public market, unseasoned trading and speculation, a potentially small number of securities available for trading, limited information about the issuer, and other factors. A Fund may hold IPO securities for a period of time, or may sell them soon after the purchase. Investments in IPOs could have a magnified impact — either positive or negative — on a Fund’s performance while the Fund’s assets are relatively small. The impact of an IPO on a Fund’s performance may tend to diminish as the Fund’s assets grow. Under circumstances in which investments in IPOs make a significant contribution to a Fund’s performance, there can be no assurance that similar contributions from IPOs will continue in the future.

Investments in Other Investment Companies

Investing in other investment companies may be a means by which a Fund seeks to achieve its investment objective. A Fund may invest in securities issued by other investment companies within the limits prescribed by the 1940 Act, the rules and regulations thereunder and any exemptive orders currently or in the future obtained by a Fund from the SEC. These securities include shares of other open-end investment companies (i.e., mutual funds), closed-end funds, exchange-traded funds and business development companies.

Except with respect to funds structured as funds-of-funds and master-feeder funds, the 1940 Act generally requires that a fund limit its investments in another investment company or series thereof so that, as determined at the time a securities purchase is made: (i) no more than 5% of the value of its total assets will be invested in the securities of any one investment company; (ii) no more than 10% of the value of its total assets will be invested in the aggregate in securities of other investment companies; and (iii) no more than 3% of the outstanding voting stock of any one investment company or series thereof will be owned by a fund or by companies controlled by the fund. Such other investment companies may include exchange-traded funds (ETFs), which are shares of publicly traded unit investment trusts, open-end funds or depositary receipts that seek to track the performance of specific indexes or companies in related industries.

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Investing in other investment companies is subject to certain risks. Although a Fund may derive certain advantages from being able to invest in shares of other investment companies, such as to be fully invested, there may be potential disadvantages. Investing in other investment companies may result in higher fees and expenses for a Fund and its shareholders. A shareholder may be charged fees not only on Fund shares held directly but also on the investment company shares that a Fund purchases.

In addition, investing in ETFs is subject to certain other risks. ETFs generally are subject to the same risks as the underlying securities the ETFs are designed to track as well as to the risks of the specific sector or industry to which the ETF relates. ETFs also are subject to the risk that their prices may not totally correlate to the prices of the underlying securities the ETFs are designed to track and the risk of possible trading halts due to market conditions or for other reasons.

Under the 1940 Act and rules and regulations thereunder, a Fund may purchase shares of affiliated funds, subject to certain conditions. Investing in affiliated Funds may present certain actual or potential conflicts of interest. For more information about such actual and potential conflicts of interest, see Investment Advisory and Other Services—Other Roles and Relationships of Ameriprise Financial and its Affiliates—Certain Conflicts of Interest.

Low and Below Investment Grade Securities

Low and below investment grade securities (below investment grade securities are also known as “junk bonds”) are debt securities with the lowest investment grade rating (e.g., BBB by S&P and Fitch or Baa by Moody’s), that are below investment grade (e.g., lower than BBB by S&P and Fitch or Baa by Moody’s) or that are unrated but determined by the Investment Manager to be of comparable quality. These types of securities may be issued to fund corporate transactions or restructurings, such as leveraged buyouts, mergers, acquisitions, debt reclassifications or similar events, are more speculative in nature than securities with higher ratings and tend to be more sensitive to credit risk, particularly during a downturn in the economy. These types of securities generally are issued by unseasoned companies without long track records of sales and earnings, or by companies or municipalities that have questionable credit strength. Low and below investment grade securities and comparable unrated securities: (i) likely will have some quality and protective characteristics that, in the judgment of one or more NRSROs, are outweighed by large uncertainties or major risk exposures to adverse conditions; (ii) are speculative with respect to the issuer’s capacity to pay interest and repay principal in accordance with the terms of the obligation; and (iii) may have a less liquid secondary market, potentially making it difficult to value or sell such securities. Low and below investment grade securities may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Investing in low and below investment grade securities and comparable unrated securities is subject to certain risks. The rates of return on these types of securities generally are higher than the rates of return available on more highly rated securities, but generally involve greater volatility of price and risk of loss of principal and income, including the possibility of default by or insolvency of the issuers of such securities. Accordingly, a Fund may be more dependent on the Investment Manager’s credit analysis with respect to these types of securities than is the case for more highly rated securities.

The market values of certain low and below investment grade securities and comparable unrated securities tend to be more sensitive to individual corporate developments and changes in economic conditions than are the market value of more highly rated securities. In addition, issuers of low and below investment grade and comparable unrated securities often are highly leveraged and may not have more traditional methods of financing available to them, so that their ability to service their debt obligations during an economic downturn or during sustained periods of rising interest rates may be impaired.

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The risk of loss due to default is greater for low and below investment grade and comparable unrated securities than it is for higher rated securities because low and below investment grade securities and comparable unrated securities generally are unsecured and frequently are subordinated to more senior indebtedness. A Fund may incur additional expenses to the extent that it is required to seek recovery upon a default in the payment of principal or interest on its holdings of such securities. The existence of limited markets for lower-rated debt securities may diminish a Fund’s ability to: (i) obtain accurate market quotations for purposes of valuing such securities and calculating portfolio net asset value (NAV); and (ii) sell the securities at the price at which they are valued by the Fund either to meet redemption requests or to respond to changes in the economy or in financial markets.

Many lower-rated securities are not registered for offer and sale to the public under the 1933 Act. Investments in these restricted securities may be determined to be liquid (able to be sold within seven days at approximately the price at which they are valued by a Fund) pursuant to policies approved by the Board. Restricted securities may be less liquid than other lower-rated securities, potentially making it difficult to value or sell such securities.

Money Market Instruments

Money market instruments are high-quality, short-term debt obligations, which include: (i) bank obligations, including certificates of deposit, time deposits and bankers’ acceptances; (ii) funding agreements; (iii) repurchase agreements; (iv) obligations of the United States, foreign countries and supranational entities, and each of their subdivisions, agencies and instrumentalities; (v) certain corporate debt securities, such as commercial paper, short-term corporate obligations and extendible commercial notes; (vi) participation interests; and (vii) municipal securities. Money market instruments may be structured as fixed-, variable- or floating rate obligations and may be publicly offered or privately placed. See Permissible Fund Investments — Variable- and Floating-Rate Obligations and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Investing in money market instruments is subject to certain risks. Money market instruments (other than certain U.S. Government obligations) are not backed or insured by the U.S. Government, its agencies or its instrumentalities. Accordingly, only the creditworthiness of an issuer, or guarantees of that issuer, support such instruments.

Mortgage-Backed Securities

Mortgage-backed securities are a type of asset-backed security and represent interests in, or debt instruments backed by, pools of underlying mortgages. In some cases, these underlying mortgages may be insured or guaranteed by the U.S. Government or its agencies. Mortgage-backed securities entitle the security holders to receive distributions that are tied to the payments made on the underlying mortgage collateral (less fees paid to the originator, servicer, or other parties, and fees paid for credit enhancement), so that the payments made on the underlying mortgage collateral effectively pass through to such security holders. Mortgage-backed securities are created when mortgage originators (or mortgage loan sellers who have purchased mortgage loans from mortgage loan originators) sell the underlying mortgages to a special purpose entity in a process called a securitization. The special purpose entity issues securities that are backed by the payments on the underlying mortgage loans, and have a minimum denomination and specific term. Mortgage-backed securities may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Mortgage-backed securities may be issued or guaranteed by the GNMA (also known as Ginnie Mae), FNMA (also known as Fannie Mae), or FHLMC (also known as Freddie Mac), but also may be issued or

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guaranteed by other issuers, including private companies. GNMA is a government-owned corporation that is an agency of the U.S. Department of Housing and Urban Development. It guarantees, with the full faith and credit of the United States, full and timely payment of all monthly principal and interest on its mortgage-backed securities. Until recently, FNMA and FHLMC were government-sponsored corporations owned entirely by private stockholders. Both issue mortgage-related securities which contain guarantees as to timely payment of interest and principal, but the securities are not backed by the full faith and credit of the U.S. Government. The value of the companies’ securities fell sharply in 2008 due to concerns that the firms did not have sufficient capital to offset losses. The U.S. Treasury has historically had the authority to purchase obligations of Fannie Mae and Freddie Mac. In addition, in 2008, due to capitalization concerns, Congress provided the U.S. Treasury with additional authority to lend Fannie Mae and Freddie Mac emergency funds and to purchase the companies’ stock, as described below. In September 2008, the U.S. Treasury and the Federal Housing Finance Agency (FHFA) announced that Fannie Mae and Freddie Mac had been placed in conservatorship.

Since 2009, Fannie Mae and Freddie Mac have received significant capital support through U.S. Treasury preferred stock purchases and Federal Reserve purchases of their mortgage backed securities. While the Federal Reserve’s purchases have terminated, the U.S. Treasury announced in December 2009 that it would continue its support for the entities’ capital as necessary to prevent a negative net worth through at least 2012. While the U.S. Treasury is committed to offset negative equity at Fannie Mae and Freddie Mac through its preferred stock purchases through 2012, no assurance can be given that the Federal Reserve, U.S. Treasury, or FHFA initiatives discussed above will ensure that Fannie Mae and Freddie Mac will remain successful in meeting their obligations with respect to the debt and mortgage-backed securities they issue beyond that date. In addition, Fannie Mae and Freddie Mac also are the subject of several continuing class action lawsuits and investigations by federal regulators over certain accounting, disclosure or corporate governance matters, which (along with any resulting financial restatements) may adversely affect the guaranteeing entities. Importantly, the future of the entities is in serious question as the U.S. Government reportedly is considering multiple options, ranging from nationalization, privatization, consolidation, or abolishment of the entities.

CMOs are debt obligations issued by special-purpose trusts, collateralized by underlying mortgage assets. Principal prepayments on underlying mortgage assets may cause the CMOs to be retired substantially earlier than their stated maturities or final distribution dates, resulting in a loss of all or part of the premium if any has been paid. Interest is paid or accrues on all classes of the CMOs on a periodic basis. The principal and interest payments on the underlying mortgage assets may be allocated among the various classes of CMOs in several ways. Typically, payments of principal, including any prepayments, on the underlying mortgage assets are applied to the classes in the order of their respective stated maturities or final distribution dates, so that no payment of principal is made on CMOs of a class until all CMOs of other classes having earlier stated maturities or final distribution dates have been paid in full.

REMICs are entities that own mortgages and elect REMIC status under the Code and, like CMOs, issue debt obligations collateralized by underlying mortgage assets that have characteristics similar to those issued by CMOs.

Investing in mortgage-backed securities is subject to certain risks, including, among others, prepayment, market and credit risks. Prepayment risk reflects the risk that borrowers may prepay their mortgages more quickly than expected, which may affect the security’s average maturity and rate of return. Whether or not a mortgage loan is prepaid is almost entirely controlled by the borrower. Borrowers are most likely to exercise prepayment options at the time when it is least advantageous to investors, generally prepaying mortgages as interest rates fall, and slowing payments as interest rates rise. Besides the effect of prevailing interest rates, the rate of prepayment and refinancing of mortgages also may be affected by home value appreciation, ease of the refinancing process and local economic conditions, among other factors. Market risk reflects the risk that the price of a security may fluctuate over time. The price of mortgage-backed securities can be particularly sensitive to prevailing interest rates, the length of time the security is expected to be outstanding and the liquidity of the issue. In a period of unstable interest rates, there may be decreased demand for certain types of mortgage-backed

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securities, which in turn may decrease their value. Credit risk reflects the risk that a holder of mortgage-backed securities may not receive all or part of its principal because the issuer, any credit enhancer and/or the underlying mortgage borrower has defaulted on its obligations. Credit risk is increased for mortgage-backed securities that are backed by mortgages to so-called subprime borrowers (who may pose a greater risk of defaulting on their loans) or that are subordinated to another security (i.e., if the holder of a mortgage-backed security is entitled to receive payments only after payment obligations to holders of the other security are satisfied). The more deeply subordinated the security, the greater the credit risk associated with the security will be. Mortgage-backed securities issued by private issuers, whether or not such obligations are subject to guarantees by the private issuer, may entail greater risk than mortgage-backed securities guaranteed by the U.S. Government. The performance of mortgage-backed securities issued by private issuers generally depends on the financial health of those institutions.

Municipal Securities

Municipal securities include debt obligations issued by governmental entities to obtain funds for various public purposes, including the construction of a wide range of public facilities, the refunding of outstanding obligations, the payment of general operating expenses, and the extension of loans to public institutions and facilities. Municipal securities can be classified into two principal categories, including “general obligation” bonds and other securities and “revenue” bonds and other securities. General obligation bonds are secured by the issuer’s full faith, credit and taxing power for the payment of principal and interest. Revenue securities are payable only from the revenues derived from a particular facility or class of facilities or, in some cases, from the proceeds of a special excise tax or other specific revenue source, such as the user of the facility being financed. Municipal securities also may include “moral obligation” securities, which normally are issued by special purpose public authorities. If the issuer of moral obligation securities is unable to meet its debt service obligations from current revenues, it may draw on a reserve fund, the restoration of which is a moral commitment but not a legal obligation of the governmental entity that created the special purpose public authority. Municipal securities may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Municipal securities may include municipal bonds, municipal notes and municipal leases. Municipal bonds are debt obligations of a governmental entity that obligate the municipality to pay the holder a specified sum of money at specified intervals and to repay the principal amount of the loan at maturity.

Municipal notes may be issued by governmental entities and other tax-exempt issuers in order to finance short-term cash needs or, occasionally, to finance construction. Most municipal notes are general obligations of the issuing entity payable from taxes or designated revenues expected to be received within the relevant fiscal period. Municipal notes generally have maturities of one year or less. Municipal notes can be subdivided into two sub-categories: (i) municipal commercial paper and (ii) municipal demand obligations.

Municipal commercial paper typically consists of very short-term unsecured negotiable promissory notes that are sold, for example, to meet seasonal working capital or interim construction financing needs of a governmental entity or agency. While these obligations are intended to be paid from general revenues or refinanced with long-term debt, they frequently are backed by letters of credit, lending agreements, note repurchase agreements or other credit facility agreements offered by banks or institutions.

Municipal demand obligations can be subdivided into two general types: variable rate demand notes and master demand obligations. Variable rate demand notes are tax-exempt municipal obligations or participation interests that provide for a periodic adjustment in the interest rate paid on the notes. They permit the holder to demand payment of the notes, or to demand purchase of the notes at a purchase price equal to the unpaid

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principal balance, plus accrued interest either directly by the issuer or by drawing on a bank letter of credit or guaranty issued with respect to such note. The issuer of the municipal obligation may have a corresponding right to prepay at its discretion the outstanding principal of the note plus accrued interest upon notice comparable to that required for the holder to demand payment. The variable rate demand notes in which a Fund may invest are payable, or are subject to purchase, on demand usually on notice of seven calendar days or less. The terms of the notes generally provide that interest rates are adjustable at intervals ranging from daily to six months.

Master demand obligations are tax-exempt municipal obligations that provide for a periodic adjustment in the interest rate paid and permit daily changes in the amount borrowed. The interest on such obligations is, in the opinion of counsel for the borrower, excluded from gross income for federal income tax purposes (but not necessarily for alternative minimum tax purposes). Although there is no secondary market for master demand obligations, such obligations are considered by a Fund to be liquid because they are payable upon demand.

Municipal lease obligations are participations in privately arranged loans to state or local government borrowers. In general, such loans are unrated, in which case they will be determined by the Investment Manager to be of comparable quality at the time of purchase to rated instruments that may be acquired by a Fund. Frequently, privately arranged loans have variable interest rates and may be backed by a bank letter of credit. In other cases, they may be unsecured or may be secured by assets not easily liquidated. Moreover, such loans in most cases are not backed by the taxing authority of the issuers and may have limited marketability or may be marketable only by virtue of a provision requiring repayment following demand by the lender.

Although lease obligations do not constitute general obligations of the municipal issuer to which the government’s taxing power is pledged, a lease obligation ordinarily is backed by the government’s covenant to budget for, appropriate, and make the payments due under the lease obligation. However, certain lease obligations contain “non-appropriation” clauses that provide that the government has no obligation to make lease or installment purchase payments in future years unless money is appropriated for such purpose on a periodic basis. In the case of a “non-appropriation” lease, a Fund’s ability to recover under the lease in the event of non-appropriation or default likely will be limited to the repossession of the leased property in the event that foreclosure proves difficult.

Tender option bonds are municipal securities having relatively long maturities and bearing interest at a fixed interest rate substantially higher than prevailing short-term tax-exempt rates that is coupled with the agreement of a third party, such as a bank, broker-dealer or other financial institution, to grant the security holders the option, at periodic intervals, to tender their securities to the institution and receive the face value thereof. The financial institution receives periodic fees equal to the difference between the municipal security’s coupon rate and the rate that would cause the security to trade at face value on the date of determination.

Investing in municipal securities is subject to certain risks. There are variations in the quality of municipal securities, both within a particular classification and between classifications, and the rates of return on municipal securities can depend on a variety of factors, including general money market conditions, the financial condition of the issuer, general conditions of the municipal bond market, the size of a particular offering, the maturity of the obligation, and the rating of the issue. The ratings of NRSROs represent their opinions as to the quality of municipal securities. It should be emphasized, however, that these ratings are general and are not absolute standards of quality, and municipal securities with the same maturity, interest rate, and rating may have different rates of return while municipal securities of the same maturity and interest rate with different ratings may have the same rate of return.

Because municipal securities are often issued to support health care, education, utilities, and transportation, a Fund’s or Portfolio Fund’s investment in municipal securities may subject the Fund to risks of those sectors, including the risks which are described below. Companies in the health care sector are subject to extensive government regulation. Their profitability can be affected significantly and adversely by, among other factors, restrictions on government reimbursement for medical expenses, government approval of medical products and services and competitive pricing pressures. Companies in the health care sector also potentially are subject to

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extensive product liability and other similar litigation. Bonds related to education may be subject to the risk of unanticipated revenue decline caused by lower enrollment, higher operating costs or decreasing governmental funding. Student loan revenue bonds are subject to the risk of default and repayment deferral, periods of forbearance, changes in federal legislation, and loss of federal or state subsidies. Bonds relating to utilities are subject to the risks facing utilities companies, such as domestic and international competition and rate changes initiated by governments and their agencies. Bonds relating to transportation are highly dependent on economic conditions and fuel costs and may be adversely affected by government regulation and local and world events.

The payment of principal and interest on most municipal securities purchased by a Fund will depend upon the ability of the issuers to meet their obligations. Each state, each of their political subdivisions, municipalities, and public authorities, as well as the District of Columbia, Puerto Rico, Guam, and the Virgin Islands, is a separate “issuer.” An issuer’s obligations under its municipal securities are subject to the provisions of bankruptcy, insolvency, and other laws affecting the rights and remedies of creditors, such as the United States Bankruptcy Code. The power or ability of an issuer to meet its obligations for the payment of interest on and principal of its municipal securities may be materially adversely affected by litigation or other conditions.

There are particular considerations and risks relevant to investing in a portfolio of a single state’s municipal securities, such as the greater risk of the concentration of portfolio holdings.

A Fund ordinarily purchases municipal securities whose interest, in the opinion of bond counsel, is excluded from gross income for federal income tax purposes. The opinion of bond counsel may assert that such interest is not an item of tax preference for the purposes of the alternative minimum tax or is exempt from certain state or local taxes. There is no assurance that applicable taxing authorities will agree with this opinion. In the event, for example, that the IRS determines that an issuer does not comply with the relevant tax requirements, interest payments from a security could become federally taxable, possibly retroactively to the date the security was issued. As a shareholder of the Fund, you may be required to file an amended tax return as a result.

Participation Interests

Participation interests (also called pass-through certificates or securities) represent an interest in a pool of debt obligations, such as municipal bonds or notes, that have been “packaged” by an intermediary, such as a bank or broker-dealer. Participation interests typically are issued by partnerships or trusts through which a Fund receives principal and interest payments that are passed through to the holder of the participation interest from the payments made on the underlying debt obligations. The purchaser of a participation interest receives an undivided interest in the underlying debt obligations. The issuers of the underlying debt obligations make interest and principal payments to the intermediary, as an initial purchaser, which are passed through to purchasers in the secondary market, such as a Fund. Mortgage-backed securities are a common type of participation interest. Participation interests may be structured as fixed-, variable- or floating-rate obligations or as zero-coupon, pay-in-kind or step-coupon securities and may be privately placed or publicly offered. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Loan participations also are a type of participation interest. Loan participations are interests in loans that are administered by a lending bank or agent for a syndicate of lending banks and sold by the bank or syndicate members.

Investing in participation interests is subject to certain risks. Participation interests generally are subject to the credit risk associated with the underlying borrowers. If the underlying borrower defaults, a Fund may be subject to delays, expenses and risks that are greater than those that would have been involved if a Fund had purchased a direct obligation of the borrower. A Fund also may be deemed a creditor of the lending bank or syndicate members and be subject to the risk that the lending bank or syndicate members may become insolvent.

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Preferred Stock

Preferred stock represents units of ownership of a corporation that frequently have dividends that are set at a specified rate. Preferred stock has preference over common stock in the payment of dividends and the liquidation of assets. Preferred stock shares some of the characteristics of both debt and equity. Preferred stock ordinarily does not carry voting rights. Most preferred stock is cumulative; if dividends are passed (i.e., not paid for any reason), they accumulate and must be paid before common stock dividends. Participating preferred stock entitles its holders to share in profits above and beyond the declared dividend, along with common shareholders, as distinguished from nonparticipating preferred stock, which is limited to the stipulated dividend. Convertible preferred stock is exchangeable for a given number of shares of common stock and thus tends to be more volatile than nonconvertible preferred stock, which generally behaves more like a fixed income bond. Preferred stock may be privately placed or publicly offered. See Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

Auction preferred stock (APS) is a type of adjustable-rate preferred stock with a dividend determined periodically in a Dutch auction process by corporate bidders. Shares typically are bought and sold at face values generally ranging from $100,000 to $500,000 per share.

In addition to reinvestment risk if interest rates fall, some specific risks with regard to APS include:

• Failed auction: A breakdown in the auction process can occur; in the event that the process fails, the rate is reset at the maximum applicable rate, which is usually described in the prospectuses and typically is influenced by the issuer’s credit rating. In a failed auction, current shareholders generally are unable to sell some, or all, of the shares when the auction is completed. Typically, the liquidity for APS that have experienced a failed auction becomes very limited. If a failed auction were to occur, the shareholder generally would hold his or her shares until the next auction. Should there not be subsequent auctions that “cure” the failed process, the shareholder may: (1) hold the APS in anticipation of a refinancing by the issuer that would cause the APS to be called, or (2) hold securities either indefinitely or in anticipation of the development of a secondary market.

• Early call risk: APS generally is redeemable at any time, usually upon notice, at the issuer’s option, at par plus accrued dividends.

Investing in preferred stock is subject to certain risks. For example, stock market risk is the risk that the value of such stocks, like the broader stock markets, may decline over short or even extended periods. Domestic and foreign stock markets tend to be cyclical, with periods when prices generally rise and periods when prices generally decline. The value of individual stocks will rise and decline based on factors specific to each corporation, such as changes in earnings or management.

Investing in preferred stock also may involve the risks applicable to investing in a particular company. For example, stocks of smaller companies tend to have greater price fluctuations than stocks of larger companies because, among other things, they trade less frequently and in lower volumes, are more susceptible to changes in economic conditions, are more reliant on singular products or services and are more vulnerable to larger competitors. Stocks of these companies may have a higher potential for gains but also are subject to greater risk of loss.

Investing in preferred stock also may involve the risks applicable to investing in a particular industry, such as technology, financial services, consumer goods or natural resources (e.g., oil and gas). To some extent, the prices of stocks tend to move by industry sector. When market conditions favorably affect, or are expected to favorably affect, an industry, the prices of the stocks of companies in that industry tend to rise. Conversely, negative news or a poor outlook for a particular industry can cause the value of those companies’ stock to decline.

Private Placement and Other Restricted Securities

Private placement securities are securities that have been privately placed and the offer and sale of which are not registered under the 1933 Act. They are eligible for sale only to certain eligible investors. Private

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placements often may offer attractive opportunities for investment not otherwise available on the open market. Private placement and other “restricted” securities often cannot be sold to the public without registration under the 1933 Act or the availability of an exemption from registration (such as Rules 144 or 144A), or they are “not readily marketable” because they are subject to other legal or contractual delays in or restrictions on resale. Asset-backed securities, common stock, convertible securities, corporate debt securities, foreign securities, low and below investment grade securities, money market instruments, mortgage-backed securities, municipal securities, participation interests, preferred stock and other types of equity and debt instruments may be privately placed or restricted securities.

Private placements typically may be sold only to qualified institutional buyers (or, in the case of the initial sale of certain securities, such as those issued in collateralized debt obligations or collateralized loan obligations, to accredited investors (as defined in Rule 501(a) under the 1933 Act)), or in a privately negotiated transaction or to a limited number of purchasers, or in limited quantities after they have been held for a specified period of time and other conditions are met pursuant to an exemption from registration.

Investing in private placement and other restricted securities is subject to certain risks. Private placements may be considered illiquid securities. Private placements typically are subject to restrictions on resale as a matter of contract or under federal securities laws. Because there may be relatively few potential purchasers for such securities, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer, a Fund could find it more difficult to sell such securities when it may be advisable to do so or it may be able to sell such securities only at prices lower than if such securities were more widely held. At times, it also may be more difficult to determine the fair value of such securities for purposes of computing a Fund’s NAV due to the absence of a trading market.

Real Estate Investment Trusts and Master Limited Partnerships

REITs are entities that either own properties or make construction or mortgage loans and also may include operating or finance companies. An equity REIT generally holds equity positions in real estate and seeks to provide its shareholders with income from the leasing of its properties and with capital gains from any sales of properties. A mortgage REIT generally specializes in lending money to owners of properties and passes through any interest income it may earn to its shareholders.

Partnership units of real estate and other types of companies sometimes are organized as master limited partnerships in which ownership interests are publicly traded. Master limited partnerships often own several properties or businesses (or directly own interests) that are related to real estate development and the oil and gas industries, but they also may finance motion pictures, research and development and other projects.

Equity investments in REITs are subject to certain risks associated with direct ownership of real estate, including, for example, declines in the value of real estate, risks related to general and local economic conditions, overbuilding and increased competition, increases in property taxes and operating expenses, and variations in rental income. REITs also may be subject to interest rate risk. In general, increases in interest rates will decrease the value of high-yield securities and increase the costs of obtaining financing, which could decrease the value of a REIT’s investments. In addition, equity REITs may be affected by changes in the value of the underlying property owned by the REITs, while mortgage REITs may be affected by the quality of credit extended. Both equity and mortgage REITs are dependent upon management skills. REITs also may be subject to heavy cash flow dependency, defaults by borrowers, and the possibility of failing to qualify for preferential tax treatment under the Code, which could adversely affect dividend payments. REITs also may not be diversified.

Equity investments in master limited partnerships generally are subject to the risks applicable to investing in a partnership as opposed to a corporation, which may include fewer protections afforded to investors. Additional risks include those associated with the specific industries in which a master limited partnership invests, such as the risks associated with investing in the real estate or oil and gas industries.

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Repurchase Agreements

Repurchase agreements are agreements under which a Fund acquires a security for a relatively short period of time subject to the obligation of a seller to repurchase and a Fund to resell such security at a fixed time and price (representing a Fund’s cost plus interest). Repurchase agreements also may be viewed as loans made by a Fund that are collateralized by the securities subject to repurchase. A Fund typically will enter into repurchase agreements only with commercial banks, registered broker-dealers and the Fixed Income Clearing Corporation (FICC). Such transactions are monitored to ensure that the value of the underlying securities will be at least equal at all times to the total amount of the repurchase obligation, including any accrued interest.

Repurchase agreements generally are subject to counterparty risk. If a counterparty defaults, a Fund could realize a loss on the sale of the underlying security to the extent that the proceeds of the sale are less than the resale price provided in the repurchase agreement including interest. In the event that a counterparty fails to perform because it is insolvent or otherwise subject to insolvency proceedings against it, a Fund’s right to take possession of the underlying securities would be subject to applicable insolvency law and procedure, including an automatic stay (which would preclude immediate enforcement of a Fund’s rights) and exemptions thereto (which would permit a Fund to take possession of the underlying securities or to void a repurchase agreement altogether). Since it is possible that an exemption from the automatic stay would not be available, a Fund might be prevented from immediately enforcing its rights against the counterparty. Accordingly, if a counterparty becomes insolvent or otherwise subject to insolvency proceedings against it, a Fund may incur delays in or be prevented from liquidating the underlying securities and could experience losses, including the possible decline in value of the underlying securities during the period in which a Fund seeks to enforce its rights thereto, possible subnormal levels of income or lack of access to income during such time, as well as the costs incurred in enforcing a Fund’s rights. For example, if a Fund enters into a repurchase agreement with a broker that becomes insolvent, it is possible for the Securities Investor Protection Corporation (SIPC) to institute a liquidation proceeding in federal court against the broker counterparty which could lead to a foreclosure by SIPC of the underlying securities or SIPC may stay, or preclude, a Fund’s ability under contract to terminate the repurchase agreement.

Reverse Repurchase Agreements

Reverse repurchase agreements are agreements under which a Fund sells a security subject to the obligation of a buyer to resell and a Fund to repurchase such security at a fixed time and price. Reverse repurchase agreements also may be viewed as borrowings made by a Fund.

Reverse repurchase agreements involve the risk that the market value of the securities a Fund is obligated to repurchase under the agreement may decline below the repurchase price. In the event the buyer of securities under a reverse repurchase agreement files for bankruptcy or becomes insolvent, a Fund’s use of proceeds of the agreement may be restricted pending a determination by the other party, or its trustee or receiver, whether to enforce a Fund’s obligation to repurchase the securities. In addition, reverse repurchase agreements are techniques involving leverage, and are subject to asset coverage requirements. Under the requirements of the 1940 Act, a Fund is required to maintain an asset coverage (including the proceeds of the borrowings) of at least 300% of all borrowings.

Sovereign Debt

A sovereign debtor’s willingness or ability to repay principal and pay interest in a timely manner may be affected by a variety of factors, including its cash flow situation, the extent of its reserves, the availability of sufficient foreign exchange on the date a payment is due, the relative size of the debt service burden to the economy as a whole, the sovereign debtor’s policy toward international lenders, and he political constraints to which a sovereign debtor may be subject. (See also Permissible Fund Investments — Foreign Securities.) In addition, there may be no legal recourse against a sovereign debtor in the event of default.

With respect to sovereign debt of emerging market issuers, investors should be aware that certain emerging market countries are among the largest debtors to commercial banks and foreign governments. At times, certain

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emerging market countries have declared moratoria on the payment of principal and interest on external debt. Certain emerging market countries have experienced difficulty in servicing their sovereign debt on a timely basis that led to defaults and the restructuring of certain indebtedness.

Sovereign debt includes Brady Bonds, which are securities issued under the framework of the Brady Plan, an initiative announced by former U.S. Treasury Secretary Nicholas F. Brady in 1989 as a mechanism for debtor nations to restructure their outstanding external commercial bank indebtedness.

Standby Commitments

Standby commitments are securities under which a purchaser, usually a bank or broker-dealer, agrees to purchase, for a fee, an amount of a Fund’s municipal obligations. The amount payable by a bank or broker-dealer to purchase securities subject to a standby commitment typically will be substantially the same as the value of the underlying municipal securities. A Fund may pay for standby commitments either separately in cash or by paying a higher price for portfolio securities that are acquired subject to such a commitment.

Using standby commitments is subject to certain risks. Standby commitments are subject to the risk that a counterparty will not fulfill its obligation to purchase securities subject to a standby commitment.

Stripped Securities

Stripped securities are securities that evidence ownership in either the future interest or principal payments on an instrument. There are many different types and variations of stripped securities. For example, Separately Traded Interest and Principal Securities, or STRIPS, can be component parts of a U.S. Treasury security where the principal and interest components are traded independently through DTC, a clearing agency registered pursuant to Section 17A of the 1934 Act, and created to hold securities for its participants, and to facilitate the clearance and settlement of securities transactions between participants through electronic computerized book-entries, thereby eliminating the need for physical movement of certificates. Treasury Investor Growth Receipts, or TIGERS, are U.S. Treasury securities stripped by brokers. Stripped mortgage-backed securities, or SMBS, also can be issued by the U.S. Government or its agencies. Stripped securities may be structured as fixed-, variable- or floating-rate obligations. See Permissible Fund Investments — Variable- and Floating-Rate Obligations for more information.

SMBS usually are structured with two or more classes that receive different proportions of the interest and principal distributions from a pool of mortgage-backed assets. Common types of SMBS will be structured so that one class receives some of the interest and most of the principal from the mortgage-backed assets, while another class receives most of the interest and the remainder of the principal.

Investing in stripped securities is subject to certain risks. If the underlying obligations experience greater than anticipated prepayments of principal, a Fund may fail fully to recoup its initial investment in such securities. The market value of the class consisting primarily or entirely of principal payments can be especially volatile in response to changes in interest rates. The rates of return on a class of SMBS that receives all or most of the interest are generally higher than prevailing market rates of return on other mortgage-backed obligations because their cash flow patterns also are volatile and there is a greater risk that the initial investment will not be recouped fully.

U.S. Government and Related Obligations

U.S. Government obligations include U.S. Treasury obligations and securities issued or guaranteed by various agencies of the U.S. Government or by various instrumentalities which have been established or sponsored by the U.S. Government. U.S. Treasury obligations and securities issued or guaranteed by various agencies of the U.S. Government differ in their interest rates, maturities and time of issuance, as well as with respect to whether they are guaranteed by the U.S. Government. U.S. Government and related obligations may be

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structured as fixed-, variable- or floating-rate obligations. See Permissible Fund Investments — Variable- and Floating-Rate Obligations for more information.

U.S. Government obligations also include senior unsecured debt securities issued between October 14, 2008 and October 31, 2009 by eligible issuers (including U.S. depository institutions insured by the Federal Deposit Insurance Corporation (FDIC) (and certain affiliates), U.S. bank holding companies and certain U.S. savings and loan holding companies) that are guaranteed by the FDIC under its Temporary Liquidity Guarantee Program (the TLGP). The FDIC’s guarantee under the TLGP will expire upon the earlier of (i) maturity of such security or (ii) December 31, 2012. It is the view of the FDIC and the staff of the SEC that any debt security that is guaranteed by the FDIC under the TLGP and that has a maturity that ends on or before December 31, 2012 would be a security exempt from registration under the Section 3(a)(2) of the 1933 Act because such security would be fully and unconditionally guaranteed by the FDIC.

Investing in securities guaranteed under the TLGP is subject to certain risks. Given that there is a limited track record for securities guaranteed under the TLGP, it is uncertain whether such securities will continue to trade in line with recent experience in relation to U.S. Treasury and government agency securities in terms of yield spread and the volatility of such spread, and it is uncertain how such securities will trade in the secondary market and whether that market will be liquid or illiquid. The TLGP is a new program that is subject to change. In order to collect from the FDIC under the TLGP, a claims process must be followed. Failure to follow the claims process could result in a loss of the right to payment under the guarantee. In addition, guarantee payments by the FDIC under the TLGP may be delayed.

Investing in U.S. Government and related obligations is subject to certain risks. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies and U.S. Government-sponsored instrumentalities may or may not be backed by the full faith and credit of the U.S. Government. These securities may be supported by the ability to borrow from the U.S. Treasury or only by the credit of the issuing agency or instrumentality and, as a result, may be subject to greater credit risk than securities issued or guaranteed by the U.S. Treasury. Obligations of U.S. Government agencies, authorities, and instrumentalities and sponsored entities historically have involved limited risk of loss of principal if held to maturity. However, no assurance can be given that the U.S. Government can or would provide financial support to any of these entities, regardless of whether it is obligated to do so by law.

On August 5, 2011, S&P lowered its long-term sovereign credit rating for the United States of America to “AA+” from “AAA”. Because a Fund may invest in U.S. Government obligations, the value of a Fund’s shares may be adversely affected by S&P’s downgrade or any future downgrades of the U.S. Government’s credit rating. While the long-term impact of the downgrade is uncertain, it could, for example, lead to increased volatility in the short-term. See Appendix A for a description of securities ratings.

Variable- and Floating-Rate Obligations

Variable- and floating-rate obligations provide for periodic adjustments in the interest rate and, under certain circumstances, varying principal amounts. Unlike a fixed interest rate, a variable, or floating, rate is one that rises and declines based on the movement of an underlying index of interest rates and may pay interest at rates that are adjusted periodically according to a specified formula. Asset-backed securities, bank obligations, convertible securities, corporate debt securities, foreign securities, low and below investment grade securities, mortgage-backed securities, money market instruments, municipal securities, participation interests, stripped securities, U.S. Government and related obligations and other types of debt instruments may be structured as variable- and floating-rate obligations.

Investing in variable- and floating-rate obligations is subject to certain risks. Variable- and floating-rate obligations may involve direct lending arrangements between the purchaser and the issuer and there may be no active secondary market, making it difficult to resell such obligations to a third party. Variable- and floating-rate

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obligations also may be subject to interest rate and credit risks. Changes in interest rates can affect the rate of return on such obligations. If an issuer of a variable- or floating rate obligation defaults, a Fund could sustain a loss to the extent of such default.

Warrants and Rights

Warrants and rights are types of securities that give a holder a right to purchase shares of common stock. Warrants usually are issued together with a bond or preferred stock and entitle a holder to purchase a specified amount of common stock at a specified price typically for a period of years. Rights usually have a specified purchase price that is lower than the current market price and entitle a holder to purchase a specified amount of common stock typically for a period of only weeks. Warrants may be used to enhance the marketability of a bond or preferred stock.

Warrants and rights may be subject to the risk that the securities could lose value. There also is the risk that the potential exercise price may exceed the market price of the warrants or rights, such as when there is no movement in the market price or the market price of such securities declines.

When-Issued, Delayed Delivery and Forward Commitment Transactions

When-issued, delayed delivery and forward commitment transactions involve the purchase or sale of securities by a Fund, with payment and delivery taking place in the future. When engaging in when-issued, delayed delivery and forward commitment transactions, a Fund typically will hold cash or liquid securities in a segregated account in an amount equal to or greater than the purchase price. The payment obligation and, if applicable, the interest rate that will be received on the securities, are fixed at the time that a Fund agrees to purchase the securities. A Fund generally will enter into when-issued, delayed delivery and forward commitment transactions only with the intention of completing such transactions. However, the Investment Manager may determine not to complete a transaction if it deems it appropriate. In such cases, a Fund may realize short-term gains or losses.

When-issued, delayed delivery and forward commitment transactions involve the risks that the securities purchased may fall in value by the time they actually are issued or that the other party may fail to honor the contract terms. A Fund that invests in delayed delivery securities may rely on a third party to complete the transaction. Failure by a third party to deliver a security purchased on a delayed delivery basis may result in a financial loss to a Fund or the loss of an opportunity to make an alternative investment.

Zero-Coupon, Pay-in-Kind and Step-Coupon Securities

Zero-coupon, pay-in-kind and step-coupon securities are types of debt instruments that do not necessarily make payments of interest in fixed amounts or at fixed intervals. Asset-backed securities, convertible securities, corporate debt securities, foreign securities, low and below investment grade securities, mortgage-backed securities, participation interests, stripped securities, U.S. Government and related obligations and other types of debt instruments may be structured as zero-coupon, pay-in-kind and step-coupon securities.

Zero-coupon securities do not pay interest on a current basis but instead accrue interest over the life of the security. These securities include, among others, zero-coupon bonds, which either may be issued at a discount by a corporation or government entity or may be created by a brokerage firm when it strips the coupons from a bond or note and then sells the bond or note and the coupon separately. This technique is used frequently with U.S. Treasury bonds, and zero-coupon securities are marketed under such names as CATS (Certificate of Accrual on Treasury Securities), TIGERs (Treasury Investor Growth Receipts) or STRIPS (Separate Trading of Registered Interest and Principal of Securities). Zero-coupon bonds also are issued by municipalities. Buying a municipal zero-coupon bond frees its purchaser of the obligation to pay regular federal income tax on imputed interest, since the interest is exempt for regular federal income tax purposes. Zero-coupon certificates of deposit and zero-coupon mortgages are generally structured in the same fashion as zero-coupon bonds; the certificate of deposit holder or mortgage holder receives face value at maturity and no payments until then.

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Pay-in-kind securities normally give the issuer an option to pay cash at a coupon payment date or to give the holder of the security a similar security with the same coupon rate and a face value equal to the amount of the coupon payment that would have been made.

Step-coupon securities trade at a discount from their face value and pay coupon interest. The coupon rate is paid according to a schedule for a series of periods, typically lower for an initial period and then increasing to a higher coupon rate thereafter. The discount from the face amount or par value depends on the time remaining until cash payments begin, prevailing interest rates, liquidity of the security and the perceived credit quality of the issue.

Zero-coupon, step-coupon and pay-in-kind securities holders generally have substantially all the rights and privileges of holders of the underlying coupon obligations or principal obligations. Holders of these securities have the right upon default on the underlying coupon obligations or principal obligations to proceed directly and individually against the issuer and are not required to act in concert with other holders of such securities.

Investing in zero-coupon, pay-in-kind and step-coupon securities is subject to certain risks, including that market prices of zero-coupon, pay-in-kind and step-coupon securities generally are more volatile than the prices of securities that pay interest periodically and in cash, and are likely to respond to changes in interest rates to a greater degree than other types of debt securities.

Because zero-coupon securities bear no interest, they are volatile. Since zero-coupon bondholders do not receive interest payments, zero-coupon securities fall more dramatically than bonds paying interest on a current basis when interest rates rise. However, when interest rates fall, zero-coupon securities rise more rapidly in value than interest paying bonds.

Borrowings

Each Fund has a fundamental policy with respect to borrowing that can be found under the heading About the Funds’ Investments — Fundamental and Non-Fundamental Investment Policies. Specifically, each Fund may not borrow money or issue senior securities except to the extent permitted by the 1940 Act, the rules and regulations thereunder and any exemptive relief obtained by the Funds. In general, pursuant to the 1940 Act, a Fund may borrow money only from banks in an amount not exceeding 33 ¹/₃% of its total assets (including the amount borrowed) less liabilities (other than borrowings). Any borrowings that come to exceed this amount must be reduced within three days (not including Sundays and holidays) to the extent necessary to comply with the 33 ¹/₃% limitation.

The Trust maintains a line of credit in order to permit borrowing on a temporary basis to meet share redemption requests in circumstances in which temporary borrowing may be preferable to liquidation of portfolio securities. Any borrowings under that line of credit by the Funds would be subject to each Fund’s restrictions on borrowing. See About the Funds’ Investments — Fundamental and Non-Fundamental Investment Policies.

Short Sales

A Fund will sometimes sell securities short when it owns an equal amount of such securities as those securities sold short. This is a technique known as selling short “against the box.” If a Fund makes a short sale “against the box,” it would not immediately deliver the securities sold and would not receive the proceeds from the sale. The seller is said to have a short position in the securities sold until it delivers the securities sold, at which time it receives the proceeds of the sale. To secure its obligation to deliver securities sold short, a Fund will deposit in escrow in a separate account with the custodian an equal amount of the securities sold short or securities convertible into or exchangeable for such securities. A Fund can close out its short position by purchasing and delivering an equal amount of the securities sold short, rather than by delivering securities already held by a Fund, because a Fund might want to continue to receive interest and dividend payments on securities in its portfolio that are convertible into the securities sold short.

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Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn European Fund, Columbia Acorn Emerging Markets Fund and Columbia Thermostat Fund may not sell securities short or maintain a short position, except short sales “against the box,” in which the Fund owns at least an equal amount of such securities, contracts or instruments or owns securities that are convertible or exchangeable into, without payment of further consideration, at least an equal amount of such securities, contracts or instruments. Other Funds, including the Portfolio Funds, under certain circumstances, may engage in short sales that are not “against the box,” which are sales by a Fund of securities or commodity futures contracts that it does not own in hopes of purchasing the same security at a later date at a lower price. The technique is also used to protect a profit in a long-term position in a security, contract or instrument. To make delivery to the buyer, a Fund must borrow or purchase the security. If borrowed, a Fund is then obligated to replace the security borrowed from the third party, so a Fund must purchase the security at the market price at a later time. If the price of the security has increased during this time, then a Fund will incur a loss equal to the increase in price of the security from the time of the short sale plus any premiums and interest paid to the third party. (Until the security is replaced, a Fund is required to pay to the lender amounts equal to any dividends or interest which accrue during the period of the loan. To borrow the security, a Fund also may be required to pay a premium, which would increase the cost of the security sold. The proceeds of the short sale will be retained by the broker, to the extent necessary to meet the margin requirements, until the short position is closed out.)

Short sales by a Fund that are not made “against the box” create opportunities to increase a Fund’s return but, at the same time, involve specific risk considerations and may be considered a speculative technique. Because a Fund in effect profits from a decline in the price of the securities sold short without the need to invest the full purchase price of the securities on the date of the short sale, a Fund’s net asset value (NAV) per share tends to increase more when the securities it has sold short decrease in value, and to decrease more when the securities it has sold short increase in value, than if it had not engaged in such short sales. The amount of any gain will be decreased, and the amount of any loss increased, by the amount of any premium, dividends or interest a Fund may be required to pay in connection with the short sale. Short sales could potentially involve unlimited loss, as the market price of securities sold short may continually increase, although a Fund can mitigate any such losses by replacing the securities sold short. Under adverse market conditions, a Fund might have difficulty purchasing securities to meet its short sale delivery obligations, and might have to sell portfolio securities to raise the capital necessary to meet its short sale obligations at a time when fundamental investment considerations would not favor such sales. There is also the risk that the third party to the short sale may fail to honor its contract terms, causing a loss to a Fund.

Short sales “against the box” entail many of the same risks and considerations described above regarding short sales not “against the box.” However, when a Fund sells short “against the box” it typically limits the amount of securities that it has leveraged. A Fund’s decision to make a short sale “against the box” may be a technique to hedge against market risks when the Investment Manager believes that the price of a security may decline, causing a decline in the value of a security owned by a Fund or a security convertible into or exchangeable for such security. In such case, any future losses in a Fund’s long position would be reduced by a gain in the short position. The extent to which such gains or losses in the long position are reduced will depend upon the amount of securities sold short relative to the amount of the securities a Fund owns, either directly or indirectly, and, in the case where a Fund owns convertible securities, changes in the investment values or conversion premiums of such securities. Short sales may have adverse tax consequences to a Fund and its shareholders.

A Fund’s successful use of short sales also will be subject to the ability of the Investment Manager to predict movements in the directions of the relevant market. A Fund therefore bears the risk that the Investment Manager will incorrectly predict future price directions. In addition, if a Fund sells a security short, and that security’s price goes up, a Fund will have to make up the margin on its open position (i.e., purchase more securities on the market to cover the position). It may be unable to do so and thus its position may not be closed out. There can be no assurance that a Fund will not incur significant losses in such a case.

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In the view of the SEC, a short sale involves the creation of a “senior security” as such term is defined in the 1940 Act, unless the sale is “against the box” and the securities sold short are placed in a segregated account (not with the broker), or unless a Fund’s obligation to deliver the securities sold short is “covered” by placing in a segregated account (not with the broker) cash, U.S. Government securities or other liquid debt or equity securities in an amount equal to the difference between the market value of the securities sold short at the time of the short sale and any such collateral required to be deposited with a broker in connection with the sale (not including the proceeds from the short sale), which difference is adjusted daily for changes in the value of the securities sold short. The total value of the cash, U.S. Government securities or other liquid debt or equity securities deposited with the broker and otherwise segregated may not at any time be less than the market value of the securities sold short at the time of the short sale.

Lending Securities

Securities lending refers to the lending of a Fund’s portfolio securities. Each Fund may lend portfolio securities representing up to one-third of the value of its total assets to broker-dealers, banks or other institutional borrowers of securities that the Funds’ securities lending agent (GSAL) has determined are creditworthy. The Funds will pay a portion of income earned on lending transactions to its securities lending agent, and also may pay administrative and custodial fees in connection with loans of securities. The cost of administering the program is included in fees paid by the Funds to the Administrator.

The Funds receive collateral, in the form of cash, equal to at least 102% under normal circumstances, of the value of the securities loaned. Loans are subject to termination at any time by the Funds or a borrower. In the event of bankruptcy or other default of a borrower, a Fund could experience delays both in liquidating the loan collateral and in recovering the loaned securities and could sustain losses, arising from, among others matters: (i) a decline in the value of the collateral or in the value of the securities loaned during the period the Fund seeks to enforce its rights thereto; (ii) lower than expected levels of income and lack of access to income during that period; (iii) expenses of enforcing the Fund’s rights; and (iv) losses on the investment or reinvestment of cash collateral.

When a Fund lends portfolio securities, payments in lieu of dividends made by the borrower to the Fund do not constitute “qualified dividends” taxable at the same rate as long-term capital gains, even if the actual dividends would have constituted qualified dividends had the Fund held the securities. A lending Fund does not have the right to vote loaned securities. In accordance with the procedures adopted by the Board, a lending Fund will attempt to call all loaned securities back to permit the exercise of voting rights, if time and jurisdictional restrictions permit. There is no guarantee that all loans can be recalled.

Portfolio Turnover

A change in the securities held by a Fund is known as “portfolio turnover.” High portfolio turnover (e.g., over 100% annually) involves correspondingly greater expenses to the Fund, including brokerage commissions or dealer mark-ups and other transaction costs on the sale of securities and reinvestments in other securities. Such sales may also result in adverse tax consequences to a Fund’s shareholders. The trading costs and tax effects associated with portfolio turnover may adversely affect a Fund’s performance.

For each Fund’s portfolio turnover rate, see the Financial Highlights section in the prospectuses for that Fund.

Under normal conditions, the portfolio turnover rates for Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn Select, Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund are expected to be below 50%, and for Columbia Acorn International Select are expected to be below 75%.

For the fiscal year ended December 31, 2010, Columbia Thermostat Fund’s portfolio turnover rate was 118%, and for the fiscal year ended December 31, 2011, it was 130%. Columbia Thermostat Fund’s portfolio

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turnover rate is based on changes in the S&P 500^® Index, which dictates the Fund’s purchase and sale of shares of the underlying Portfolio Funds in which it invests. Under normal conditions the portfolio turnover rate for Columbia Thermostat Fund is expected to be below 150%. Because Columbia Thermostat Fund is a Fund of Funds that exchanges shares of the Portfolio Funds at NAV, the costs associated with Columbia Thermostat Fund’s portfolio turnover rate are lower than the costs that would be associated with another fund that had the same portfolio turnover rate but directly bore the trading costs of its portfolio transactions.

Disclosure of Portfolio Information

The Board and the Investment Manager believe that the investment ideas and trading strategies of the Investment Manager with respect to portfolio management of a Fund should benefit the Fund and its shareholders, and do not want to afford speculators an opportunity to profit by anticipating Fund trading strategies or by using Fund portfolio holdings information for stock picking. However, the Board also believes that knowledge of a Fund’s portfolio holdings can assist shareholders in monitoring their investments, making asset allocation decisions, and evaluating portfolio management techniques.

The Board has therefore adopted policies and procedures relating to disclosure of the Funds’ portfolio securities. These policies and procedures are intended to protect the confidentiality of Fund portfolio holdings information and generally prohibit the release of such information until it is made available to the general public. It is the policy of the Funds not to provide or permit others to provide portfolio holdings on a selective basis, and the Investment Manager does not intend to selectively disclose portfolio holdings in advance of public dissemination.

The Investment Manager does not expect that such holdings information will be selectively disclosed, except where necessary for the Funds’ operation or where there are other legitimate business purposes for doing so and, in any case, where conditions are met that are designed to protect the interests of the Funds and their shareholders, including that the recipients are subject to a duty of confidentiality, including a duty not to trade on the nonpublic information. These policies and procedures prohibit Ameriprise Financial, the Investment Manager and the Funds’ other service providers from entering into any agreement to disclose Fund portfolio holdings information or trading strategies in violation of the policies and procedures and from entering into any agreement to disclose portfolio information in exchange for any form of consideration. The policies and procedures incorporate and adopt the supervisory controls and recordkeeping requirements established in the Investment Manager’s policies and procedures. The Investment Manager has also adopted policies and procedures to monitor for compliance with the Funds’ portfolio holdings disclosure policies and procedures.

Although the Investment Manager seeks to limit the selective disclosure of portfolio holdings information and such selective disclosure is monitored under the Funds’ compliance program for conformity with the policies and procedures, there can be no assurance that the policies and procedures will protect the Funds from the potential misuse of holdings information by individuals or firms in possession of that information.

Public Disclosures

The Funds’ portfolio holdings are currently disclosed to the public through required filings with the SEC and on the Funds’ website. Once posted, the portfolio holdings information will remain available on the website until at least the date on which a Fund files a Form N-CSR or Form N-Q for the period that includes the date as of which the information is current. The Funds’ complete holdings (and in the case of Columbia Thermostat Fund, percentage holdings of the Portfolio Funds) are disclosed on the Funds’ website at www.columbiamanagement.com as of a month-end approximately 30 calendar days after such month-end. In addition, the largest 10 to 15 holdings of each Fund are usually available sooner, approximately 15 calendar days after each month-end. Purchases and sales of the Funds’ portfolio securities can take place at any time, so the portfolio holdings information available to the website may not always be current. The scope of the information disclosed on the Funds’ website pursuant to the policies and procedures described above also may change from time to time, without prior notice.

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The Funds file their portfolio holdings with the SEC for each fiscal quarter on either Form N-CSR (with respect to each annual period and semiannual period) or Form N-Q (with respect to the first and third quarters of the Funds’ fiscal year). Shareholders may obtain the Funds’ Forms N-CSR and N-Q filings on the SEC’s website at www.sec.gov, a link to which is provided on the Funds’ website at www.columbiamanagement.com. In addition, the Funds’ Forms N-CSR and N-Q filings may be reviewed and copied at the SEC’s public reference room in Washington, D.C. You may call the SEC at 202.551.8090 for information about the SEC’s website or the operation of the public reference room.

The Funds, the Investment Manager, Ameriprise Financial or their affiliates may include portfolio holdings information that has already been made public through a web posting or SEC filing in marketing literature and other communications to shareholders, financial advisors or other parties. In addition, certain advisory clients of the Investment Manager that follow a strategy similar to that of a Fund have access to their own custodial account’s portfolio holdings information before such Fund posts its holdings on the Funds’ website at www.columbiamanagement.com. It is possible that when clients observe transactions in their own accounts, they may infer transactions of the Funds prior to public disclosure of Fund transactions.

Other Disclosures

Pursuant to the policies and procedures described above, the Funds may selectively disclose their portfolio holdings information in advance of public disclosure on a confidential basis to various Fund service providers that require such information for the legitimate business purpose of assisting the Funds with day-to-day business affairs.

In determining the existence of a legitimate business purpose for making portfolio disclosures, the following factors, among others, are considered: (i) any prior disclosure must be consistent with the anti fraud provisions of the federal securities laws and the fiduciary duties of the Investment Manager; (ii) any conflicts of interest between the interests of Fund shareholders, on the one hand, and those of the Investment Manager, the Distributor or any affiliated person of a Fund, the Investment Manager or Distributor on the other; and (iii) any prior disclosure to a third party, although subject to a confidentiality agreement, would not make conduct lawful that is otherwise unlawful.

In addition, the Funds periodically disclose their portfolio information on a confidential basis to various service providers that require such information to assist the Funds with their day-to-day business affairs. In addition to the Investment Manager and its affiliates, these service providers include, but are not limited to, affiliates of the Investment Manager, the Funds’ custodian, any any sub-custodians, independent registered public accounting firm, legal counsel, financial printers, proxy solicitor and proxy voting service provider, as well as ratings agencies that maintain ratings on certain Funds. These service providers are required to keep such information confidential, and are prohibited from trading based on the information or otherwise using the information except as necessary in providing services to the Funds. The Funds also may disclose portfolio holdings information to broker-dealers and certain other entities in connection with potential transactions and management of the Funds, provided that reasonable precautions, including limitations on the scope of the portfolio holdings information disclosed, are taken to avoid any potential misuse of the disclosed information.

The Fund also discloses portfolio holdings information as required by federal, state or international securities laws, and may disclose portfolio holdings information in response to requests by governmental authorities, or in connection with litigation or potential litigation, a restructuring of a holding, where such disclosure is necessary to participate or explore participation in a restructuring of the holding (e.g., as part of a bondholder group), or to the issuer of a holding, pursuant to a request of the issuer or any other party who is duly authorized by the issuer.

Neither the Funds nor Ameriprise Financial, the Investment Manager or their affiliates receive compensation or consideration from the service providers for the portfolio holdings information. In addition to

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Ameriprise Financial, the Investment Manager and their affiliates, including Threadneedle International Limited, these service providers are listed below. Portfolio holdings information disclosed to such recipients is current as of the time of its disclosure, is disclosed to each recipient solely for purposes consistent with the services described below, and has been authorized in accordance with the policy.

IDENTITY OF RECIPIENT	PURPOSE OF DISCLOSURE	FREQUENCY OF DISCLOSURE
Wilshire Associates	Supports performance analysis software.	Daily
JPMorgan	Funds’ Custodian; receives trade files containing information for the Funds.	Daily
Sikich ICS	Host of the Funds’ Trustee website.	Monthly
Linedata (MFACT)	Provides support for the Investment Manager’s accounting systems.	As needed, generally less than twice per year
Investment Technology Group	Provides support for the Investment Manager’s trading system.	As needed, generally less than twice per year
Factset Research Data Systems, Inc.	Provides quantitative analysis, charting and fundamental data to investment, marketing, performance and distribution personnel.	Daily
Interactive Data Corporation (IDC)	Provides statistical fair valuation services to support the Investment Manager.	As needed
Merrill Corporation	Printer for the Funds’ prospectuses, SAIs, supplements and sales materials.	As needed
RR Donnelley Financial	Printer for the Funds’ prospectuses, SAIs, supplements and sales materials.	As needed
Abel Noser	Evaluation and assessment of trading activity, execution and practices by the Investment Manager.	As needed, generally no less than quarterly
Bloomberg, L.P.	Provides support for the Investment Manager’s trading system; evaluation and assessment of trading activity, execution and practices by the Investment Manager.	Daily
GSAL	Funds’ securities lending agent.	As needed in connection with the Funds’ securities lending program

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IDENTITY OF RECIPIENT	PURPOSE OF DISCLOSURE	FREQUENCY OF DISCLOSURE
Institutional Shareholder Services, Inc. (ISS)	Proxy service provider to the Funds. Holdings are only redistributed by ISS through voting the shares held and within the Funds’ N-PX filings.	Daily
Perkins Coie LLP	Legal counsel to the Funds.	As needed
Drinker Biddle & Reath LLP	Legal counsel to the Independent Trustees.	As needed
ING Insurance Company	Provides quarterly fact sheets.	Quarterly
PricewaterhouseCoopers LLP	Funds’ independent registered public accounting firm, providing audit services, tax return review services, and assistance in connection with the review of various SEC filings.	As needed

Pursuant to agreements in such form as the Chief Compliance Officer (CCO) of the Funds may require, these service providers are required to keep such information confidential, and are prohibited from trading based on the information or otherwise using the information except as necessary in providing services to the Funds.

The Funds have authorized the Investment Manager’s President (and his designated subordinates) to make appropriate disclosures of the Funds’ holdings to certain Ameriprise Financial affiliates (to provide monitoring of compliance with codes of ethics and to monitor various holdings limitations that must be aggregated with affiliated funds, among other purposes), to provide the Custodian, sub-custodians and pricing service with daily trade information, to disclose necessary portfolio information to the Funds’ proxy service. The Funds have also authorized the Investment Manager’s President and Chief Operating Officer (and their designated subordinates) to disclose portfolio information to independent auditors in connection with audit procedures. In addition, the Funds have authorized Ameriprise Financial and the Investment Manager’s President (and his designated subordinates) to disclose necessary information to printing firms engaged by Ameriprise Financial to prepare periodic reports to Fund shareholders.

The Investment Manager uses a variety of broker-dealers and other agents to effect securities transactions on behalf of the Funds. These broker-dealers become aware of the Funds’ intentions, transactions and positions, in performing their functions. Further, the Funds’ ability to identify and execute transactions in securities is dependent, in part, on information provided to the Investment Manager by broker-dealers who are market makers in certain securities or otherwise have the ability to assist the Funds in executing their orders. To facilitate that process, the Board has authorized the Investment Manager’s President and Director of Global Trading (and their designated subordinates) to disclose portfolio information or anticipated transactions to broker-dealers who may execute Fund transactions. This disclosure is limited to that information necessary to effect the Funds’ securities transactions and assist the Investment Manager in seeking to obtain best execution.

The CCO is responsible for implementation of the Funds’ portfolio holdings disclosure policies and procedures. The CCO is required to report to the Board any violations of the policies and procedures that come to his attention and may approve non-public disclosures of a Fund’s portfolio holdings. Such disclosure must be consistent with the policies and procedures in that it furthers a legitimate business purpose of a Fund, is therefore in the best interests of that Fund’s shareholders and is appropriately reported to the Board.

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INVESTMENT ADVISORY AND OTHER SERVICES

The Investment Manager and Investment Advisory Services

Columbia Wanger Asset Management, LLC (CWAM or the Investment Manager) (operating as a limited partnership prior to May 1, 2010 and named Wanger Asset Management, L.P. prior to September 29, 2000), serves as the investment adviser for the Funds, the series of Wanger Advisors Trust and other institutional accounts. The Investment Manager and its predecessors have managed mutual funds, including Columbia Acorn Fund, since 1992.

As of September 30, 2012, the Investment Manager had assets under management of approximately $32 billion.

The Investment Manager is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, and is a registered investment adviser and wholly owned subsidiary of Columbia Management, which is a wholly owned subsidiary of Ameriprise Financial. Prior to May 1, 2010, when the long-term asset management business of Columbia Management Group, LLC, including 100% of the Investment Manager, was acquired by Ameriprise Financial, the Investment Manager was a wholly owned subsidiary of Bank of America. Prior to April 1, 2004, when FleetBoston Financial Corporation (Fleet) was acquired by Bank of America, Columbia Management Group, LLC was a wholly owned subsidiary of Fleet.

Under the 1940 Act, the May 1, 2010 closing of the acquisition (the Acquisition) of the Investment Manager by Ameriprise Financial (the Closing) caused the Trust’s investment advisory agreement with the Investment Manager dated August 1, 2007 (the Prior Advisory Agreement) to terminate. At a special meeting held on May 27, 2010, as recommended by the Board, shareholders approved the Trust’s Advisory Agreement (with respect to each of the Funds other than Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund), which initially took effect immediately and continued in effect through July 31, 2011. At a Meeting held on March 2, 2011, the Board approved the Advisory Agreement with respect to Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund, to be effective on August 19, 2011. The Advisory Agreement continues from year to year with respect to each Fund, until terminated by either the Trust or the Investment Manager, as long as it is specifically approved at least annually by either the Board or by a vote of the majority of the outstanding shares of the Fund and by the vote of a majority of the Independent Trustees, cast in person at a meeting called for the purpose of voting on such approval.

The Board approved an interim investment advisory agreement (the Interim Advisory Agreement) with the Investment Manager for each Fund (other than Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund), which became effective as of the Closing and which remained in effect until the May 27, 2010 shareholder approval of the Advisory Agreement. The terms of the Interim Advisory Agreement were the same as those of the Prior Advisory Agreement, except for certain provisions that were required by law and the date and term of the agreement.

The Advisory Agreement generally provides that, subject to the overall supervision and control of the Board, the Investment Manager shall have supervisory responsibility for the general management and investment of the Funds’ assets and will endeavor to preserve the autonomy of the Trust. Under the Advisory Agreement, the Investment Manager is authorized to make decisions to buy and sell securities and other assets for the Funds, to place the Funds’ portfolio transactions with broker-dealers and to negotiate the terms of such transactions including brokerage commissions on brokerage transactions on behalf of the Funds. The Investment Manager is authorized to exercise discretion within the Trust’s policy concerning allocation of its portfolio brokerage, as permitted by law, and in so doing shall not be required to make any reduction in its investment advisory fees. The Investment Manager is required to use its best efforts to seek to obtain the best overall terms available for portfolio transactions for each Fund. See Brokerage Allocation and Other Practices—General Brokerage Policy, Brokerage Transactions and Broker Selection.

The Investment Manager, at its own expense, provides office space, facilities and supplies, equipment and personnel for the performance of its functions under the Advisory Agreement. The Trust pays all compensation

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of the Independent Trustees (although certain fees were reimbursed by the Investment Manager and its affiliated persons in connection with the Acquisition).

Under the Advisory Agreement, the Investment Manager is not liable for any loss suffered by a Fund or its shareholders as a result of any error of judgment, or any loss arising out of any investment, or as a consequence of any other act or omission of the Investment Manager or any of its affiliates in the performance of the Investment Manager’s duties under the agreement, except for (i) with respect to acts or omissions in respect of investment activities, liability resulting from willful misfeasance, bad faith, reckless disregard or gross negligence, and (ii) with respect to all other matters, liability resulting from bad faith, intentional misconduct or negligence, on the part of the Investment Manager or its affiliates.

A discussion regarding the basis of the Board’s approval of the continuation, through July 31, 2012, of the Advisory Agreement with respect to the Funds other than Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund is available in the Funds’ semiannual report to shareholders for the period ended June 30, 2011. A discussion regarding the Board’s approval of the continuation, through July 31, 2013, of the Advisory Agreement with respect to each Fund will be available in the Funds’ semiannual report to shareholders for the period ending June 30, 2012.

Advisory Fee Rates and Fees Paid

The Funds pay the Investment Manager an annual fee for its investment advisory services as shown in the section entitled Fees and Expenses — Annual Fund Operating Expenses in each Fund’s prospectuses. The advisory fee is calculated as a percentage of the average daily net assets of each Fund and is paid monthly. The advisory fee rates payable to the Investment Manager under the Advisory Agreement are identical to those payable under the Prior Advisory Agreement. The Investment Manager may pay amounts from its own assets to the Distributor and/or to selling agents for services they provide.

The Investment Manager also received advisory fees from certain of the Portfolio Funds in which Columbia Thermostat Fund invests. Please refer to the Portfolio Funds’ respective prospectuses, which are available on the Columbia Funds website at www.columbiamanagement.com and on the SEC’s website at www.sec.gov.

The Investment Manager received fees from the Funds for its services as reflected in the following chart, which shows the advisory fees paid to the Investment Manager and the fees waived/reimbursed by the Investment Manager, where applicable, for the three most recently completed fiscal years.

Advisory Fees Paid by the Funds

Fund	Fiscal Year Ended December 31, 2011		Fiscal Year Ended December 31, 2010		Fiscal Year Ended December 31, 2009
Columbia Acorn Fund
Gross Advisory Fee	$	114,050,000	$	99,409,000	$	77,909,000
Amount Waived/Reimbursed by the Investment Manager	$	0	$	0	$	0
Net Advisory Fee	$	114,050,000	$	99,409,000	$	77,909,000
Columbia Acorn International
Gross Advisory Fee	$	46,342,000	$	37,945,000	$	26,444,000
Amount Waived/Reimbursed by the Investment Manager	$	159,000	$	0	$	0
Net Advisory Fee	$	46,183,000	$	37,945,000	$	26,444,000
Columbia Acorn USA
Gross Advisory Fee	$	14,918,000	$	12,548,000	$	9,677,000
Amount Waived/Reimbursed by the Investment Manager	$	0	$	0	$	0
Net Advisory Fee	$	14,918,000	$	12,548,000	$	9,677,000

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Fund	Fiscal Year Ended December 31, 2011			Fiscal Year Ended December 31, 2010			Fiscal Year Ended December 31, 2009
Columbia Acorn Select
Gross Advisory Fee	$	15,322,000		$	16,589,000		$	12,761,000
Amount Waived/Reimbursed by the Investment Manager	$	0		$	0		$	0
Net Advisory Fee	$	15,322,000		$	16,589,000		$	12,761,000
Columbia Acorn International Select
Gross Advisory Fee	$	3,885,000		$	3,892,000		$	3,039,000
Amount Waived/Reimbursed by the Investment Manager	$	0		$	2,000		$	5,000
Net Advisory Fee	$	3,885,000		$	3,890,000		$	3,034,000
Columbia Acorn European Fund
Gross Advisory Fee	$	7,000			N/A*			N/A*
Amount Waived/Reimbursed by the Investment Manager	$	174,000			N/A*			N/A*
Net Advisory Fee	$	(167,000	)		N/A*			N/A*
Columbia Acorn Emerging Markets Fund
Gross Advisory Fee	$	13,000			N/A*			N/A*
Amount Waived/Reimbursed by the Investment Manager	$	182,000			N/A*			N/A*
Net Advisory Fee	$	(169,000	)		N/A*			N/A*
Columbia Thermostat Fund
Gross Advisory Fee	$	141,000		$	125,000		$	128,000
Amount Waived/Reimbursed by the Investment Manager	$	216,000		$	267,000		$	327,000
Net Advisory Fee	$	(75,000	)	$	(142,000	)	$	(199,000	)

* Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund commenced operations on August 19, 2011.

The Investment Manager has voluntarily agreed to reimburse a portion of the expenses of Columbia Acorn Select and Columbia Acorn International Select (excluding brokerage commissions, interest, taxes and extraordinary expenses, but including custodial charges relating to overdrafts, if any), after giving effect to any balance credits from the Custodian, so that ordinary operating expenses do not exceed (i) the annual rates of 1.70%, 2.20%, 2.45%, 1.28%, 1.45%, 1.33%, 1.28% and 1.45% of Columbia Acorn International Select’s average daily net assets attributable to Class A, Class B, Class C, Class I, Class R4, Class R5, Class Y and Class Z shares, respectively, on an annualized basis and (ii) the annual rates of 1.60%, 2.10%, 2.35%, 1.25%, 1.35%, 1.30%, 1.25% and 1.35% of Columbia Acorn Select’s average daily net assets attributable to Class A, Class B, Class C, Class I, Class R4, Class R5, Class Y and Class Z shares, respectively, on an annualized basis. This arrangement may be modified or terminated by either the Investment Manager or a Fund on 30 days notice to the other.

With respect to Columbia Thermostat Fund, the Investment Manager has contractually agreed to bear a portion of the Fund’s expenses so that the Fund’s ordinary operating expenses (excluding distribution and service fees, expenses associated with investments in other investment companies and interest and fees on borrowings, but including custodial charges relating to overdrafts, if any), after giving effect to any balance credits from the Custodian, do not exceed (i) the annual rate of 0.25% of the Fund’s average daily net assets attributable to Class A, Class B, Class C and Class Z shares, through April 30, 2013, on an annualized basis and (ii) the annual rates of 0.25%, 0.27% and 0.22% of the Fund’s average daily net assets attributable to Class R4, Class R5 and Class Y shares, respectively, through November 8, 2012, on an annualized basis. There is no guarantee that these arrangements will continue thereafter. In addition to the fees and expenses paid by Columbia Thermostat Fund directly, Columbia Thermostat Fund pays its pro rata share of the fees and expenses of the Portfolio Funds in which it invests.

With respect to Columbia Acorn European Fund, the Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that the ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rates of 1.75%, 2.50%, 1.31%, 1.36% and 1.50% of the Fund’s average daily net assets

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attributable to Class A, Class C, Class I, Class R5 and Class Z shares, respectively, through April 30, 2013 for Class A, Class C, Class I and Class Z shares, and through November 8, 2013 for Class R5 shares. The Investment Manager may recoup any fees waived and/or expenses reimbursed with respect to any share class of the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in this prospectus, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This expense arrangement may only be modified or amended in writing with approval from all parties to such arrangements, including the Trust and the Investment Manager. This expense agreement may be terminated only upon the mutual agreement of the Board and the Investment Manager.

With respect to Columbia Acorn Emerging Markets Fund, the Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that the ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rates of 1.85%, 2.60%, 1.41%, 1.60% and 1.46% and 1.60% of the Fund’s average daily net assets attributable to Class A, Class C, Class I, Class R4, Class R5 and Class Z shares, respectively, through April 30, 2013 for Class A, Class C, Class I and Class Z shares, and through November 8, 2013 for Class R4 and Class R5 shares. The Investment Manager may recoup any fees waived and/or expenses reimbursed with respect to any share class of the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in this prospectus, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This expense arrangement may only be modified or amended in writing with approval from all parties to such arrangements, including the Trust and the Investment Manager. This expense agreement may be terminated only upon the mutual agreement of the Board and the Investment Manager.

Portfolio Managers

The following provides additional information about the portfolio managers of the Investment Manager who are responsible for making the day-to-day investment decisions for the Funds. As described in the Management of the Fund — Primary Service Providers section of each Fund’s prospectuses, the portfolio managers of the Investment Manager who are responsible for the Funds are:

Portfolio Managers of the Investment Manager

Portfolio Manager	Fund
Ben Andrews	Columbia Acorn Select
Robert A. Chalupnik	Columbia Acorn Select
P. Zachary Egan	Columbia Acorn International Columbia Acorn Emerging Markets Fund
Fritz Kaegi	Columbia Acorn Emerging Markets Fund
Stephen Kusmierczak	Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund
Charles P. McQuaid	Columbia Acorn Fund Columbia Thermostat Fund
Louis J. Mendes	Columbia Acorn International Columbia Acorn Emerging Markets Fund
Robert A. Mohn	Columbia Acorn Fund Columbia Acorn USA
Christopher J. Olson	Columbia Acorn International Select
Andreas Waldburg-Wolfegg	Columbia Acorn European Fund

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Compensation

For services performed for the 2011 calendar year and incentives paid in early 2012, Messrs. Andrews, Chalupnik, Egan, Kaegi, Kusmierczak, McQuaid, Mendes, Mohn, Olson and Waldburg-Wolfegg and analysts and other key employees of the Investment Manager received all of their compensation in the form of salary and incentive compensation provided in whole by Ameriprise Financial. Typically, a high proportion of an analyst’s or portfolio manager’s incentive compensation is paid in cash with a smaller proportion going into two separate incentive plans. The first plan is a notional investment based on the performance of certain Columbia Funds, including the Columbia Acorn Funds. The second plan consists of Ameriprise Financial restricted stock and/or options. Both plans vest over three years from the date of issuance.

Portfolio managers and key analysts are positioned in compensation tiers based on cumulative performance of the portfolios/stocks that they manage. Portfolio manager performance is measured versus primary portfolio benchmarks. Analyst performance is measured versus a custom benchmark for each analyst. One- and three-year performance periods primarily drive incentive levels. Incentive compensation varies by tier and can range from between a fraction of base pay to a multiple of base pay, the objective being to provide very competitive total compensation for high performing analysts and portfolio managers. Incentives are adjusted up or down up to 15% based on qualitative performance factors, which include investment performance impacts not included in benchmarks such as industry (or country) weighting recommendations, plus adherence to compliance standards, business building, and citizenship. Less seasoned analysts’ incentives are also based on performance versus benchmarks, though they are less formulaic in order to emphasize investment process instead of initial investment results. The qualitative factors discussed above are also considered. These analysts participate in an incentive pool which is based on a formula primarily driven by firm-wide investment performance.

In addition, the incentive amounts available for the entire pool for 2012 will be adjusted up or down based upon the increase/decrease in the Investment Manager’s revenues versus an agreed upon base revenue amount. Investment performance, however, impacts incentives far more than revenues. The Investment Manager determines incentive compensation, subject to review by Ameriprise Financial.

Performance Benchmarks

Portfolio Manager	Benchmark(s)
Ben Andrews (Columbia Acorn Select)	S&P MidCap 400® Index (primary benchmark), S&P 500® Index and Lipper Mid-Cap Growth Funds Index
Robert A. Chalupnik (Columbia Acorn Select)	S&P MidCap 400® Index (primary benchmark), S&P 500® Index and Lipper Mid-Cap Growth Funds Index
P. Zachary Egan (Columbia Acorn International)	S&P Global Ex-U.S. Between $500 Million and $5 Billion® Index (primary benchmark), S&P Global Ex-U.S. Small Cap® Index, MSCI Europe, Australasia and Far East (MSCI EAFE) Index (Net) and Lipper International Small/Mid Growth Funds Index
P. Zachary Egan (Columbia Acorn Emerging Markets Fund)	S&P Emerging Markets $500 Million to $5 Billion® Index (primary benchmark), MSCI Emerging Markets Small Cap Index and Lipper Emerging Markets Index
Fritz Kaegi (Columbia Acorn Emerging Markets Fund)	S&P Emerging Markets $500 Million to $5 Billion® Index (primary benchmark), MSCI Emerging Markets Small Cap Index and Lipper Emerging Markets Index
Stephen Kusmierczak (Columbia Acorn European Fund)	S&P Europe $500 Million to $5 Billion® Index (primary benchmark), HSBC Smaller European Companies Index and Lipper European Region Index
Stephen Kusmierczak (Columbia Acorn Emerging Markets Fund)	S&P Emerging Markets $500 Million to $5 Billion® Index (primary benchmark), MSCI Emerging Markets Small Cap Index and Lipper Emerging Markets Index

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Portfolio Manager	Benchmark(s)
Charles P. McQuaid (Columbia Acorn Fund)	Russell 2500 Index (primary benchmark), S&P 500® Index, Russell 2000 Index and Lipper Mid-Cap Growth Funds Index
Charles P. McQuaid (Columbia Thermostat Fund)	S&P 500® Index (primary equity benchmark), Barclays U.S. Aggregate Bond Index (primary debt benchmark), Lipper Flexible Portfolio Funds Index and the 50/50 Blended Benchmark (an equally weighted custom composite of the Fund’s primary equity and debt benchmarks, established by the Investment Manager)
Louis J. Mendes (Columbia Acorn International)	S&P Global Ex-U.S. Between $500 Million and $5 Billion® Index (primary benchmark), S&P Global Ex-U.S. Small Cap® Index, MSCI EAFE Index (Net) and Lipper International Small/Mid Growth Funds Index
Louis J. Mendes (Columbia Acorn Emerging Markets Fund)	S&P Emerging Markets $500 Million to $5 Billion® Index (primary benchmark), MSCI Emerging Markets Small Cap Index and Lipper Emerging Markets Index
Robert A. Mohn (Columbia Acorn Fund)	Russell 2500 Index (primary benchmark), S&P 500® Index, Russell 2000 Index and Lipper Mid-Cap Growth Funds Index
Robert A. Mohn (Columbia Acorn USA)	Russell 2000 Index (primary benchmark) and Lipper Small-Cap Growth Funds Index
Christopher J. Olson (Columbia Acorn International Select)	S&P Developed Ex-U.S. Between $2 Billion and $10 Billion® Index (primary benchmark), MSCI EAFE Index (Net) and Lipper International Small/Mid Growth Funds Index
Andreas Waldburg-Wolfegg (Columbia Acorn European Fund)	S&P Europe $500 Million to $5 Billion® Index (primary benchmark), HSBC Smaller European Companies Index and Lipper European Region Index

Other Accounts Managed by the Portfolio Managers as of December 31, 2011

The following table shows the number and assets of other investment accounts (or portions of investment accounts) that the portfolio managers of the Investment Manager managed in addition to the Funds.

Portfolio Manager	Other SEC-registered  open- end and closed-end funds				Other pooled investment vehicles				Other accounts
	Number of accounts		Assets		Number of accounts		Assets		Number of accounts		Assets
Ben Andrews		1	$	242,543,407		0	$	0		3	$	7,663,896
Robert A. Chalupnik		2	$	397,890,575		0	$	0		2	$	454,633
P. Zachary Egan		1	$	523,134,719		0	$	0		9	$	252,602,388
Charles P. McQuaid		0	$	0		0	$	0		8	$	912,416,622
Fritz Kaegi		0	$	0		0	$	0		6	$	1,594,354
Stephen Kusmierczak		0	$	0		1	$	22,727,131		6	$	2,796,043
Louis J. Mendes		2	$	1,205,351,969		0	$	0		7	$	252,799,220
Robert A. Mohn		3	$	1,583,588,758		1	$	48,018,959		5	$	881,222,977
Christopher J. Olson		2	$	706,235,759		0	$	0		8	$	1,517,951
Andreas Waldburg-Wolfegg		0	$	0		1	$	22,727,131		6	$	2,472,545

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Other Accounts Managed by the Portfolio Managers for which the Advisory Fee is Based on Performance

As of December 31, 2011, none of the Funds’ portfolio managers managed an account for which the advisory fee was based on performance.

Ownership of Securities

Portfolio Manager Ownership as of December 31, 2011

The table below shows the dollar ranges of shares of each Fund beneficially owned (as determined pursuant to Rule 16a-1(a)(2) under the 1934 Act) by the portfolio managers of the Funds as of December 31, 2011.

Portfolio Manager	Fund	Dollar Range of Equity Securities in the Fund Beneficially Owned
Ben Andrews	Columbia Acorn Select Columbia Acorn International Columbia Thermostat Fund	over $1,000,000 $1 - $10,000 $100,001 - $500,000
Robert A. Chalupnik	Columbia Acorn Fund Columbia Acorn USA Columbia Acorn Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund	$100,001 - $500,000 $100,001 - $500,000 $100,001 - $500,000 $10,001 - $50,000 $50,001 - $100,000
P. Zachary Egan	Columbia Acorn Fund Columbia Acorn International Columbia Acorn International Select Columbia Acorn Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund Columbia Thermostat Fund	$10,001 - $50,000 over $1,000,000 $100,001 - $500,000 $50,001 - $100,000 $100,001 - $500,000 $100,001 - $500,000 $10,001 - $50,000
Fritz Kaegi	Columbia Acorn Fund Columbia Acorn International Columbia Acorn USA Columbia Acorn Select Columbia Acorn International Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund	$50,001 - $100,000 $100,001 - $500,000 $10,001 - $50,000 $1 - $10,000 $1 - $10,000 $50,001 - $100,000 $100,001 - $500,000
Stephen Kusmierczak	Columbia Acorn Fund Columbia Acorn International Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund Columbia Thermostat Fund	$100,001 - $500,000 $500,001 - $1,000,000 $100,001 - $500,000 $100,001 - $500,000 $1 - $10,000

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Portfolio Manager	Fund	Dollar Range of Equity Securities in the Fund Beneficially Owned
Charles P. McQuaid	Columbia Acorn Fund Columbia Acorn International Columbia Acorn USA Columbia Acorn Select Columbia Acorn International Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund Columbia Thermostat Fund	over $1,000,000 over $1,000,000 over $1,000,000 over $1,000,000 $500,001 - $1,000,000 $500,001 - $1,000,000 $100,001 - $500,000 over $1,000,000
Louis J. Mendes	Columbia Acorn Fund Columbia Acorn International Columbia Acorn Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund	$10,001 - $50,000 over $1,000,000 $1 - $10,000 $50,001 - $100,000 $100,001 - $500,000
Robert A. Mohn	Columbia Acorn Fund Columbia Acorn International Columbia Acorn USA Columbia Acorn Select Columbia Acorn International Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund	$500,001 - $1,000,000 $500,001 - $1,000,000 over $1,000,000 $100,001 - $500,000 $50,001 - $100,000 $10,001 - $50,000 $50,001 - $100,000
Christopher J. Olson	Columbia Acorn International Select	$100,001 - $500,000
Andreas Waldburg-Wolfegg	Columbia Acorn International Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund	$100,001 - $500,000 $100,001 - $500,000 $100,001 - $500,000

The Investment Manager’s Portfolio Managers and Potential Conflicts of Interests

Like other investment professionals with multiple clients, a Fund’s portfolio manager(s) may face certain potential conflicts of interest in connection with managing both the Fund and other accounts at the same time. The Investment Manager and the Funds have adopted compliance policies and procedures that attempt to address certain of the potential conflicts that portfolio managers face in this regard. Certain of these conflicts of interest are summarized below.

The management of accounts with different advisory fee rates and/or fee structures, including accounts that pay advisory fees based on account performance (performance fee accounts), if any, may raise potential conflicts of interest for a portfolio manager by creating an incentive to favor higher fee accounts.

Potential conflicts of interest also may arise when a portfolio manager has personal investments in other accounts that may create an incentive to favor those accounts. As a general matter and subject to the Investment Manager’s Code of Ethics and certain limited exceptions, the Investment Manager’s investment professionals do not have the opportunity to invest in client accounts, other than the Funds and the series of Wanger Advisors Trust.

A portfolio manager who is responsible for managing multiple funds and/or accounts may devote unequal time and attention to the management of those funds and/or accounts. The effects of this potential conflict may

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be more pronounced where funds and/or accounts managed by a particular portfolio manager have different investment strategies.

A portfolio manager may be able to select or influence the selection of the broker-dealers that are used to execute securities transactions for the Funds. A portfolio manager’s decision as to the selection of broker-dealers could produce disproportionate costs and benefits among the Funds and the other accounts the portfolio manager manages.

A potential conflict of interest may arise when a portfolio manager buys or sells the same securities for a Fund and other accounts. On occasions when a portfolio manager considers the purchase or sale of a security to be in the best interests of a Fund as well as other accounts, the Investment Manager’s trading desk may, to the extent consistent with applicable laws and regulations, aggregate the securities to be sold or bought in order to obtain the best execution and lower brokerage commissions, if any. Aggregation of trades may create the potential for unfairness to a Fund or another account if a portfolio manager favors one account over another in allocating the securities bought or sold.

“Cross trades,” in which a portfolio manager sells a particular security held by a Fund to another account (potentially saving transaction costs for both accounts), could involve a potential conflict of interest if, for example, a portfolio manager is permitted to sell a security from one account to another account at a higher price than an independent third party would pay. The Investment Manager and the Funds have adopted compliance procedures that provide that any transactions between a Fund and another account managed by the Investment Manager are to be made at an independent current market price, consistent with applicable laws and regulation.

Another potential conflict of interest may arise based on the different investment objectives and strategies of a Fund and other accounts managed by its portfolio manager(s). Depending on another account’s objectives and other factors, a portfolio manager may give advice to and make decisions for a Fund that may differ from advice given, or the timing or nature of decisions made, with respect to another account. A portfolio manager’s investment decisions are the product of many factors in addition to basic suitability for the particular account involved. Thus, a portfolio manager may buy or sell a particular security for certain accounts, and not for a Fund, even though it could have been bought or sold for the Fund at the same time. A portfolio manager also may buy a particular security for one or more accounts when one or more other accounts are selling the security (including short sales). There may be circumstances when a portfolio manager’s purchases or sales of portfolio securities for one or more accounts may have an adverse effect on other accounts, including the Funds.

A Fund’s portfolio manager(s) also may have other potential conflicts of interest in managing the Fund, and the description above is not a complete description of every conflict that could exist in managing the Fund and other accounts. Many of the potential conflicts of interest to which the Investment Manager’s portfolio managers are subject are essentially the same as or similar to the potential conflicts of interest related to the investment management activities of the Investment Manager and its affiliates. See Investment Advisory and Other Services — Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest for more information about conflicts of interest, including those that relate to the Investment Manager and its affiliates.

The Administrator

CWAM (which is also the Investment Manager) serves as Administrator of the Funds.

Services Provided

Pursuant to the terms of the Administration Agreement, the Administrator provides certain administrative services to each Fund, including: (i) maintaining the books and records, including financial and corporate records, of the Trust, and providing pricing and bookkeeping services to the Funds; (ii) supervising the preparation and

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filing of registration statements, notices, reports, proxy statements, tax returns and other documents, as deemed necessary or desirable by the Trust; (iii) overseeing and assisting in the coordination of the performance of administrative and third party professional services rendered to the Funds, including the Funds’ securities lending agent; (iv) providing corporate secretarial services and data processing facilities and calculating and arranging for notice and payment of distribution to shareholders; (v) developing and implementing procedures to monitor each Fund’s compliance with regulatory requirements and with each Fund’s investment policies and restrictions; (vi) providing for the services of employees of the Administrator who may be appointed as officers of the Trust; and (vii) providing services to shareholders of the Funds. The Administration Agreement may be terminated by the Board or the Administrator upon 60 days written notice. The Administrator has the power under the Administration Agreement to delegate some or all of its responsibilities to others, at the Administrator’s expense. The Administrator retains responsibility for any services it delegates.

The Administrator has delegated a majority of its responsibilities under the Administration Agreement to Columbia Management as the Funds’ Sub-Administrator. The Sub-Administrator provides certain of the above enumerated services to the Funds, including fund accounting services, and receives a fee from the Administrator for such services.

Administration Fee Rates and Fees Paid

The Administrator receives compensation for its administration services, which is computed daily and paid monthly as a percentage of the average daily net assets of each Fund at the annual rates shown in each Fund’s prospectuses.

The following chart shows the administration fees paid to the Administrator for the three most recently completed fiscal years.

Administration Fees Paid by the Funds

Fund	Fiscal Year Ended December 31, 2011		Fiscal Year Ended December 31, 2010		Fiscal Year Ended December 31, 2009
Columbia Acorn Fund
Administration Fee	$	6,839,000	$	6,176,000	$	5,179,000
Columbia Acorn International
Administration Fee	$	2,343,000	$	1,979,000	$	1,459,000
Columbia Acorn USA
Administration Fee	$	666,000	$	580,000	$	477,000
Columbia Acorn Select
Administration Fee	$	720,000	$	813,000	$	666,000
Columbia Acorn International Select
Administration Fee	$	159,000	$	165,000	$	138,000
Columbia Acorn European Fund
Administration Fee	$	240		N/A*		N/A*
Columbia Acorn Emerging Markets Fund
Administration Fee	$	400		N/A*		N/A*
Columbia Thermostat Fund
Administration Fee	$	54,000	$	50,000	$	55,000

* Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund commenced operations on August 19, 2011.

The Administrator did not waive or reimburse any Fund’s administration fees for the fiscal years ended December 31, 2011, December 31, 2010 or December 31, 2009.

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The Principal Underwriter/Distributor

Columbia Management Investment Distributors, Inc. (formerly known as RiverSource Fund Distributors, Inc.) (the Distributor) serves as the principal underwriter and distributor of the shares of the Funds. The Distributor is a wholly owned subsidiary of Ameriprise Financial. Its address is: 225 Franklin Street, Boston, MA 02110.

Prior to May 1, 2010, Columbia Management Distributors, Inc. (CMD) served as the principal underwriter and distributor of the shares of the Funds.

Distribution Obligations

Pursuant to the Distribution Agreement, the Distributor, as agent, sells shares of the Funds on a continuous basis and transmits purchase and redemption orders that it receives to the Trust or the Transfer Agent. Additionally, the Distributor has agreed to use appropriate efforts to solicit orders for the sale of shares and to undertake advertising and promotion as it believes appropriate in connection with such solicitation. Pursuant to the Distribution Agreement, the Distributor, at its own expense, finances those activities which are primarily intended to result in the sale of shares of the Funds, including, but not limited to, advertising, compensation of underwriters, dealers and sales personnel, the printing of prospectuses to other than existing shareholders, and the printing and mailing of sales literature. The Distributor, however, may be compensated or reimbursed for all or a portion of such expenses to the extent permitted by a Distribution Plan adopted by the Trust pursuant to Rule 12b-1 under the 1940 Act.

The Distribution Agreement became effective with respect to each Fund after approval by the Board, and continues from year to year, provided that such continuation of the Distribution Agreement is specifically approved at least annually by (i) the Board, or (ii) a majority vote of the Funds’ outstanding securities, provided that in either instance, the continuance is also approved by the majority of the Independent Trustees who are not parties to the agreement, by vote cast in person at a meeting called for the purpose of voting such approval. The Distribution Agreement terminates automatically in the event of its assignment, and is terminable with respect to each Fund at any time without penalty by the Trust (by vote of the Board or by vote of a majority of the outstanding voting securities of the Fund) or by the Distributor on 60 days written notice.

Underwriting Commissions

The following table shows all commissions and other compensation received by the Distributor and CMD (the former distributor of the Funds’ shares), as well as amounts the Distributor and CMD retained, after paying commissions and other expenses, during the Funds’ three most recent fiscal years.

Because they commenced operations on August 19, 2011, amounts are not shown for Columbia Acorn European Fund or Columbia Acorn Emerging Markets Fund for periods prior to the fiscal year ended December 31, 2011.

	Class A Shares Fiscal Year Ended December 31, 2011
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Acorn European Fund		Columbia Acorn Emerging Markets Fund		Columbia Thermostat Fund
Aggregate initial sales charges on Fund share sales	$	2,294,592	$	416,728	$	77,372	$	137,201	$	41,658	$	863	$	2,612	$	481,213
Initial sales charges retained by the Distributor	$	319,613	$	58,492	$	10,839	$	19,084	$	7,314	$	0	$	0	$	67,586

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	Class A Shares Fiscal Year Ended December 31, 2011
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Acorn European Fund		Columbia Acorn Emerging Markets Fund		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by the Distributor	$	3,650	$	6,693	$	0	$	0	$	28	$	0	$	0	$	0

	Class B Shares Fiscal Year Ended December 31, 2011
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Acorn European Fund		Columbia Acorn Emerging Markets Fund		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by the Distributor	$	35,379	$	23,136	$	1,894	$	8,649	$	1,830	$	0	$	0	$	5,952

	Class C Shares Fiscal Year Ended December 31, 2011
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Acorn European Fund		Columbia Acorn Emerging Markets Fund		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by the Distributor	$	42,550	$	10,549	$	1,047	$	1,960	$	911	$	0	$	100	$	946

	Class A Shares Fiscal Year Ended December 31, 2010
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Thermostat Fund
Aggregate initial sales charges on Fund share sales	$	1,717,767	$	508,460	$	94,987	$	227,877	$	49,100	$	144,300
Aggregate initial sales charges retained by CMD/the Distributor	$	252,880	$	71,375	$	12,582	$	31,833	$	7,076	$	44,324
Aggregate contingent deferred sales charges (CDSC) on Fund redemptions retained by CMD/the Distributor	$	2,424	$	287	$	209	$	1,070	$	17	$	31

	Class B Shares Fiscal Year Ended December 31, 2010
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by CMD/the Distributor	$	107,495	$	39,669	$	5,458	$	44,723	$	2,987	$	13,134

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	Class C Shares Fiscal Year Ended December 31, 2010
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by CMD/the Distributor	$	30,730	$	7,364	$	1,148	$	6,264	$	1,621	$	1,248

	Class A Shares Fiscal Year Ended December 31, 2009
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Thermostat Fund
Aggregate initial sales charges on Fund share sales	$	1,309,125	$	377,949	$	45,595	$	181,610	$	49,837	$	96,935
Initial sales charges retained by CMD	$	200,550	$	58,351	$	6,730	$	27,468	$	7,436	$	14,764
Aggregate CDSC on Fund redemptions retained by CMD	$	152	$	1,735	$	0	$	9	$	0	$	0

	Class B Shares Fiscal Year Ended December 31, 2009
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by CMD	$	300,064	$	59,565	$	14,025	$	99,190	$	6,363	$	57,194

	Class C Shares Fiscal Year Ended December 31, 2009
	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn Select		Columbia Acorn International Select		Columbia Thermostat Fund
Aggregate CDSC on Fund redemptions retained by CMD	$	28,853	$	7,380	$	382	$	2,343	$	3,319	$	3,375

  Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest

As described above in the Investment Advisory and Other Services section of this SAI, and in the Management of the Fund — Primary Service Providers section of each Fund’s prospectus, the Investment Manager, Administrator, Sub-Administrator, Distributor and Transfer Agent, all affiliates of Ameriprise Financial, receive compensation from the Funds for the various services they provide to the Funds. Additional information as to the specific terms regarding such compensation is set forth in these affiliated service providers’ contracts with the Funds, each of which typically is included as an exhibit to Part C of each Fund’s registration statement.

In many instances, the compensation paid to the Investment Manager and other Ameriprise Financial affiliates for the services they provide to the Funds is based, in some manner, on the size of the Funds’ assets

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under management. As the size of the Funds’ assets under management grows, so does the amount of compensation paid to the Investment Manager and other Ameriprise Financial affiliates for providing services to the Funds. This relationship between Fund assets and affiliated service provider compensation may create economic and other conflicts of interests of which Fund investors should be aware. These potential conflicts of interest, as well as additional ones, are discussed in detail below and also are addressed in other disclosure materials, including the Funds’ prospectuses. These conflicts of interest also are highlighted in account documentation and other disclosure materials of Ameriprise Financial affiliates that make available or offer the Columbia Funds as investments in connection with their respective products and services. In addition, the Investment Manager’s Form ADV, which it must file with the SEC as an investment adviser registered under the Investment Advisers Act of 1940, provides information about the Investment Manager’s business, assets under management, affiliates and potential conflicts of interest. Parts 1 and 2 of the Investment Manager’s Form ADV are available online through the SEC’s website at www.adviserinfo.sec.gov.

Additional actual or potential conflicts of interest and certain investment activity limitations that could affect the Funds may arise from the financial services activities of Ameriprise Financial and its affiliates, including, for example, the investment advisory/management services provided for clients and customers other than the Funds. In this regard, Ameriprise Financial is a major financial services company. Ameriprise Financial and its affiliates, are engaged in a wide range of financial activities beyond the mutual fund-related activities of the Investment Manager, including, among others, broker-dealer (sales and trading), asset management, insurance and other financial activities. The broad range of financial services activities of Ameriprise Financial and its affiliates may involve multiple advisory, transactional, lending, financial and other interests in securities and other instruments, and in companies, that may be bought, sold or held by the Funds. The following describes certain actual and potential conflicts of interest that may be presented.

Actual and Potential Conflicts of Interest Related to the Investment Advisory/Management Activities of Ameriprise Financial and its Affiliates in Connection With Other Advised/Managed Funds and Accounts

The Investment Manager and other affiliates of Ameriprise Financial may advise or manage funds and accounts other than the Funds. In this regard, Ameriprise Financial and its affiliates may provide investment advisory/management and other services to other advised/managed funds and accounts that are similar to those provided to the Funds. The Investment Manager and Ameriprise Financial’s other investment adviser affiliates (including, for example, Columbia Management) will give advice to and make decisions for all advised/managed funds and accounts, including the Funds, as they believe to be in that fund’s and/or account’s best interests, consistent with their fiduciary duties. The Funds and the other advised/managed funds and accounts of Ameriprise Financial and its affiliates are separately and potentially divergently managed, and there is no assurance that any investment advice Ameriprise Financial and its affiliates give to other advised/managed funds and accounts will also be given simultaneously or otherwise to the Funds.

A variety of other actual and potential conflicts of interest may arise from the advisory relationships of the Investment Manager and other Ameriprise Financial affiliates with other clients and customers. Advice given to the Funds and/or investment decisions made for the Funds by the Investment Manager or other Ameriprise Financial affiliates may differ from, or may conflict with, advice given to and/or investment decisions made for other advised/managed funds and accounts. As a result, the performance of the Funds may differ from the performance of other funds or accounts advised/managed by the Investment Manager or other Ameriprise Financial affiliates. Similarly, a position taken by Ameriprise Financial and its affiliates, including the Investment Manager, on behalf of other funds or accounts may be contrary to a position taken on behalf of the Funds. Moreover, Ameriprise Financial and its affiliates, including the Investment Manager, may take a position on behalf of other advised/managed funds and accounts, or for their own proprietary accounts, that is adverse to companies or other issuers in which the Funds are invested. For example, the Funds may hold equity securities of a company while another advised/managed fund or account may hold debt securities of the same company. If the portfolio company were to experience financial difficulties, it might be in the best interest of the Funds for the company to reorganize while the interests of the other advised/managed fund or account might be better served

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by the liquidation of the company. This type of conflict of interest could arise as the result of circumstances that cannot be generally foreseen within the broad range of investment advisory/management activities in which Ameriprise Financial and its affiliates engage.

Investment transactions made on behalf of other funds or accounts advised/managed by the Investment Manager or other Ameriprise Financial affiliates also may have a negative effect on the value, price or investment strategies of the Funds. For example, this could occur if another advised/managed fund or account implements an investment decision ahead of, or at the same time as, the Funds and causes the Funds to experience less favorable trading results than they otherwise would have experienced based on market liquidity factors. In addition, the other funds and accounts advised/managed by the Investment Manager and other Ameriprise Financial affiliates, including the other Columbia Funds, may have the same or very similar investment objective and strategies as the Funds. In this situation, the allocation of, and competition for, investment opportunities among the Funds and other funds and/or accounts advised/managed by the Investment Manager or other Ameriprise Financial affiliates may create conflicts of interest especially where, for example, limited investment availability is involved. The Investment Manager has adopted policies and procedures addressing the allocation of investment opportunities among the Funds and other funds and accounts advised by the Investment Manager and other affiliates of Ameriprise Financial. For more information, see Investment Advisory and Other Services — The Investment Manager and Investment Advisory Services — Portfolio Managers — The Investment Manager’s Portfolio Managers and Potential Conflicts of Interests.

Sharing of Information among Advised/Managed Accounts

Ameriprise Financial and its affiliates also may possess information that could be material to the management of a Fund and may not be able to, or may determine not to, share that information with the Fund, even though the information might be beneficial to the Fund. This information may include actual knowledge regarding the particular investments and transactions of other advised/managed funds and accounts, as well as proprietary investment, trading and other market research, analytical and technical models, and new investment techniques, strategies and opportunities. Depending on the context, Ameriprise Financial and its affiliates generally will have no obligation to share any such information with the Funds. In general, employees of Ameriprise Financial and its affiliates, including the portfolio managers of the Investment Manager, will make investment decisions without regard to information otherwise known by other employees of Ameriprise Financial and its affiliates, and generally will have no obligation to access any such information and may, in some instances, not be able to access such information because of legal and regulatory constraints or the internal policies and procedures of Ameriprise Financial and its affiliates. For example, if the Investment Manager or another Ameriprise Financial affiliate, or their respective employees, come into possession of non-public information regarding another advised/managed fund or account, they may be prohibited by legal and regulatory constraints, or internal policies and procedures, from using that information in connection with transactions made on behalf of the Funds. For more information, see Investment Advisory and Other Services — The Investment Manager and Investment Advisory Services — Portfolio Managers — The Investment Manager’s Portfolio Managers and Potential Conflicts of Interests.

Soft Dollar Benefits

Certain products and services, commonly referred to as “research products” (including, to the extent permitted by law, research reports, economic and financial data, financial publications, proxy analysis, computer databases and other research-oriented materials), that the Investment Manager may receive in connection with brokerage services provided to a Fund may have the inadvertent effect of disproportionately benefiting other advised/managed funds or accounts. This could happen because of the relative amount of brokerage services provided to a Fund as compared to other advised/managed funds or accounts, as well as the relative compensation paid by a Fund. For more information, see Brokerage Allocation and Other Practices — Brokerage Commissions.

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Services Provided to Other Advised/Managed Accounts

Ameriprise Financial and its affiliates also may act as an investment adviser, investment manager, administrator, transfer agent, custodian, trustee, broker-dealer, agent, or in another capacity, for advised/managed funds and accounts other than the Funds, and may receive compensation for acting in such capacity. This compensation that the Investment Manager, Distributor and Transfer Agent and other Ameriprise Financial affiliates receive could be greater than the compensation Ameriprise Financial and its affiliates receive for acting in the same or similar capacity for the Funds. In addition, the Investment Manager, Distributor and Transfer Agent and other Ameriprise Financial affiliates may receive other benefits, including enhancement of new or existing business relationships. This compensation and/or the benefits that Ameriprise Financial and its affiliates may receive from other advised/ managed funds and accounts and other relationships could potentially create incentives to favor other advised/managed funds and accounts over the Funds. Trades made by Ameriprise Financial and its affiliates for the Funds may be, but are not required to be, aggregated with trades made for other funds and accounts advised/managed by the Investment Manager and other Ameriprise Financial affiliates. If trades are aggregated among the Funds and those other funds and accounts, the various prices of the securities being traded may be averaged, which could have the potential effect of disadvantaging the Funds as compared to the other funds and accounts with which trades were aggregated.

Proxy Voting

Although the Investment Manager endeavors to make all proxy voting decisions with respect to the interests of the Funds for which it is responsible in accordance with its proxy voting policies and procedures, the Investment Manager’s proxy voting decisions with respect to a Fund’s portfolio securities may nonetheless benefit other advised/managed funds and accounts, and/or clients, of Ameriprise Financial and its affiliates. The Investment Manager has adopted proxy voting policies and procedures that are designed to provide that all proxy voting is done in the best interests of its clients, including the Funds, without any resulting benefit or detriment to the Investment Manager and/or its affiliates, including Ameriprise Financial and its affiliates. For more information about the Investment Manager’s proxy voting policies and procedures, see Investment Advisory and Other Services — Proxy Voting Policies and Procedures.

Certain Trading Activities

The directors/trustees, officers and employees of Ameriprise Financial and its affiliates may buy and sell securities or other investments for their own accounts, and in doing so may take a position that is adverse to the Funds. In order to reduce the possibility that such personal investment activities of the directors/trustees, officers and employees of Ameriprise Financial and its affiliates will materially adversely affect the Funds, Ameriprise Financial and its affiliates have adopted policies and procedures, and the Funds, the Board, the Investment Manager and the Distributor have each adopted a Code of Ethics that addresses such personal investment activities. For more information, see Investment Advisory and Other Services — Codes of Ethics.

Affiliate Transactions

Subject to applicable legal and regulatory requirements, the Funds may enter into transactions in which Ameriprise Financial and/or its affiliates may have an interest that potentially conflicts with the interests of the Funds. For example, an affiliate of Ameriprise Financial may sell securities to the Funds from an offering in which it is an underwriter or from securities that it owns as a dealer, subject to applicable legal and regulatory requirements.

Investment Limitations Arising from Ameriprise Financial Activities

Regulatory restrictions applicable to Ameriprise Financial and its affiliates may limit the Funds’ investment activities in various ways. For example, regulations regarding certain industries and markets, such as those in

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emerging or international markets, and certain transactions, such as those involving certain futures and derivatives, may impose a cap on the aggregate amount of investments that may be made by affiliated investors, including accounts managed by the same affiliated manager, in the aggregate or in individual issuers. At certain times, Ameriprise Financial and its affiliates also may be restricted in the securities that can be bought or sold for the Funds and other advised/managed funds and accounts because of the investment banking, lending or other relationships Ameriprise Financial and its affiliates have with the issuers of securities. This could happen, for example, if the Funds and/or other advised/managed funds and accounts desired to buy a security issued by a company for which Ameriprise Financial or its affiliates served as underwriter. The internal policies and procedures of Ameriprise Financial and its affiliates covering these types of regulatory restrictions and addressing similar issues also may at times restrict the Funds’ investment activities. A client not advised by Ameriprise Financial and its affiliates would not be subject to many of these restrictions. See also About the Funds’ Investments — Certain Investment Activity Limits.

Actual and Potential Conflicts of Interest Related to Ameriprise Financial and its Affiliates’ Non-Advisory Relationships with Clients and Customers other than the Funds

The financial relationships that Ameriprise Financial and its affiliates may have with companies and other entities in which a Fund may invest can give rise to actual and potential conflicts of interest. Subject to applicable legal and regulatory requirements, a Fund may invest (a) in the securities of Ameriprise Financial and/or its affiliates and/or in companies in which Ameriprise Financial and its affiliates have an equity, debt or other interest, and/or (b) in the securities of companies held by other Columbia Funds. The purchase, holding and sale of such securities by a Fund may enhance the profitability and the business interests of Ameriprise Financial and/or its affiliates and/or other Columbia Funds. There also may be limitations as to the sharing with the Investment Manager of information derived from the non-investment advisory/management activities of Ameriprise Financial and its affiliates because of legal and regulatory constraints and internal policies and procedures (such as information barriers and ethical walls). Because of these limitations, Ameriprise Financial and its affiliates generally will not share information derived from its non-investment advisory/management activities with the Investment Manager.

Actual and Potential Conflicts of Interest Related to Ameriprise Financial Affiliates’ Marketing and Use of the Columbia Funds as Investment Options

Ameriprise Financial and its affiliates also provide a variety of products and services that, in some manner, may utilize the Columbia Funds as investment options. For example, the Columbia Funds may be offered as investments in connection with brokerage and other securities products offered by Ameriprise Financial and its affiliates, and may be utilized as investments in connection with fiduciary, investment management and other accounts offered by affiliates of Ameriprise Financial, as well as for other Columbia Funds structured as “funds of funds.” The use of the Columbia Funds in connection with other products and services offered by Ameriprise Financial and its affiliates may introduce economic and other conflicts of interest. These conflicts of interest are highlighted in account documentation and other disclosure materials for the other products and services offered by Ameriprise Financial and its affiliates.

Ameriprise Financial and its affiliates, including the Investment Manager, may make payments to their affiliates in connection with the promotion and sale of the Funds’ shares, in addition to the sales-related and other compensation that these parties may receive from the Funds. As a general matter, personnel of Ameriprise Financial and its affiliates do not receive compensation in connection with their sales or use of the Funds that is greater than that paid in connection with their sales of other comparable products and services. Nonetheless, because the compensation that the Investment Manager and other affiliates of Ameriprise Financial may receive for providing services to the Funds is generally based on the Funds’ assets under management and those assets will grow as shares of the Funds are sold, potential conflicts of interest may exist. See Brokerage Allocation and Other Practices — Additional Selling Agent Payments for more information.

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Other Service Providers

The Transfer Agent

Columbia Management Investment Services Corp. (formerly known as RiverSource Service Corporation) acts as Transfer Agent for each Fund’s shares and can be contracted at P.O. Box 8081, Boston, MA 02266-8081. The Transfer Agent is a subsidiary of Ameriprise Financial. Under the Transfer Agency Agreement, the Transfer Agent is responsible for providing transfer agency, dividend disbursing and shareholder servicing services to the Funds (Shareholder Services). The Transfer Agent has engaged DST/BFDS as the Funds’ sub-transfer agent to provide certain Shareholder Services and assist the Transfer Agent is carrying out its duties. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which investors may hold Fund shares; these intermediaries also may provide Shareholder Services. For more information, see Brokerage Allocation and Other Practices — Additional Shareholder Servicing Payments.

Through April 30, 2013, the Funds pay the Transfer Agent a base per account fee of $18.50 ($20.00 beginning May 1, 2013) for each account held directly with the Transfer Agent, and reimburse the Transfer Agent for certain out-of-pocket expenses. Such out-of-pocket expenses are approved by the Trustees from time to time, and may include networking account fees paid to dealer firms by the Transfer Agent on shareholder accounts established or maintained pursuant to the National Securities Clearing Corporation’s (NSCC) networking system. In addition, subject to certain limitations, the Funds reimburse payments made by the Transfer Agent to financial intermediaries for the Shareholder Services that the intermediaries provide, in amounts that vary by share class and also vary with the type of intermediary and the type of Shareholder Services provided. Generally, through April 30, 2013, each Columbia Acorn Fund reimburses the Transfer Agent for the cost of Shareholder Services at a rate of (i) 0.115% of the average aggregate value of the Fund’s shares attributable to financial intermediaries that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders of the Fund; or (ii) an annual fee of $12.25 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by certain mutual fund trading platforms (also known as “fund supermarkets”) and other financial intermediaries not covered by clause (i), provided that (a) total combined Transfer Agent fees and payments for Shareholder Services by Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class and (b) Class Y shares do not make any reimbursement payments for Shareholder Services. Amounts in excess of those reimbursed by a Fund are borne by the Distributor, the Investment Manager and/or their affiliates. Class I shares currently make no Transfer Agent fee and no Shareholder Services reimbursement payments. The Transfer Agent does not pay financial intermediaries for Shareholder Services and the Funds do not reimburse the Transfer Agent for any Shareholder Services provided by financial intermediaries with respect to Class I and Class Y shares.

The Transfer Agent may also retain as additional compensation for its services all of its revenues for fees for wire, telephone and redemption orders, IRA trustee agent fees and account transcripts due the Transfer Agent from shareholders of the Fund and interest (net of bank charges) earned with respect to the balances in accounts the Transfer Agent maintains in connection with its services to the Funds.

DST/BFDS is located at 2 Heritage Drive, North Quincy, MA 02171.

The Custodian

JPMorgan, One Chase Manhattan Plaza, New York, New York 10005, is the Custodian of the Funds’ assets. It is responsible for holding all securities and cash of the Funds, receiving and paying for securities purchased, delivering against payment securities sold, receiving and collecting income from investments and performing other administrative duties, all as directed by authorized persons of the Funds. The Investment Manager and Columbia Management supervise JPMorgan in such matters as the purchase and sale of portfolio securities. Portfolio securities purchased in the United States are maintained in the custody of JPMorgan or other domestic banks or depositories. Portfolio securities purchased outside of the United States are maintained in the custody of foreign banks and trust companies who are members of JPMorgan’s foreign depository and foreign sub-custodial network.

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With respect to foreign depositories and foreign sub-custodians, there can be no assurance that a Fund, and the value of its shares, will not be adversely affected by acts of foreign governments, financial or operational difficulties of the foreign sub-custodians, difficulties and costs of obtaining jurisdiction over, or enforcing judgments against, the foreign sub-custodians or application of foreign law to a Fund’s foreign sub-custodial arrangements. Accordingly, an investors should recognize that the noninvestment risks involved in holding assets abroad are greater than those associated with holding assets in the U.S.

The Funds may invest in obligations of JPMorgan and may purchase securities from or sell securities to JPMorgan.

Prior to July 22, 2011, State Street served as the custodian for the assets of the Columbia Acorn Funds.

Independent Registered Public Accounting Firm

PricewaterhouseCoopers LLP, located at One North Wacker, Chicago, Illinois 60606, serves as the Funds’ independent registered public accounting firm, providing audit services, tax return review services and assistance and consultation in connection with the review of various SEC filings.

Audited Financial Statements. The report of the Funds’ independent registered public accounting firm and the audited financial statements included in the Funds’ annual reports to shareholders dated December 31, 2011, are incorporated herein by reference. No other parts of the annual reports are incorporated by reference herein. The audited financial statements incorporated by reference into the Fund’s prospectuses and this SAI have been so incorporated in reliance upon the report of the independent registered public accounting firm, given on its authority as an expert in auditing and accounting.

Unaudited Semiannual Financial Statements. The unaudited financial statements included in the Funds’ semiannual reports to shareholders dated June 30, 2012 are incorporated herein by reference. No other parts of the semiannual reports are incorporated by reference herein.

Counsel

Perkins Coie LLP serves as counsel to the Funds. Drinker Biddle & Reath LLP serves as counsel to the Independent Trustees. Perkins Coie LLP is located at 700 13^th Street, N.W., Washington, DC 20005. Drinker Biddle & Reath LLP is located at One Logan Square, Suite 200, Philadelphia, PA 19103.

Securities Lending Agent

GSAL, 125 High Street, Oliver Street Tower, Suite 1700, Boston, MA 02110, is the Funds’ securities lending agent. As such, GSAL is responsible, among other things for: entering into and maintaining securities loan agreements with borrowers; negotiating fees with borrowers; delivering securities to borrowers; receiving collateral from borrowers in connection with loans; and investing cash collateral in accordance with instructions received from the Investment Manager.

Distribution Plan

The Trustees have approved a Distribution Plan pursuant to Rule 12b-1 under the 1940 Act for each of the Funds’ Class A, Class B, Class C and Class R shares. Class I, Class R4, Class R5, Class Y and Class Z shares of the Funds do not pay service and distribution fees. Under the Distribution Plan, each Fund pays the Distributor monthly service and distribution fees at the annual rates described in the prospectuses for that Fund’s Class A, Class B, Class C and Class R shares. The Distributor may use the entire amount of such fees to defray the costs of commissions and service fees paid to selling agents and for certain other purposes. Since the distribution and service fees are payable regardless of the Distributor’s expenses, the Distributor may realize a profit from the fees. Effective February 29, 2008, the Funds no longer accept investments from new or existing investors in Class B shares of the Funds. See the prospectuses for Class B shares of the Funds for details.

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The Distribution Plan authorizes payments by the Funds to the Distributor and its affiliates (including the Investment Manager) with respect to the Funds’ Class A, Class B, Class C and Class R shares to the extent that such payments might be construed to be indirect financing of the distribution of those shares.

The Board believes the Distribution Plan could be a significant factor in the growth and retention of Fund assets resulting in a more advantageous expense ratio and increased investment flexibility which could benefit each class of Fund shareholders. The Distribution Plan will continue in effect from year to year so long as its continuance is specifically approved at least annually by a vote of the Trustees, including the Independent Trustees that have no direct or indirect financial interest in the operation of the Distribution Plan or in any agreements related to the Plan, by vote cast in person at a meeting called for the purpose of voting on the Distribution Plan. The Distribution Plan may not be amended to increase the fee materially without approval by vote of a majority of the outstanding voting securities of the relevant class of shares and all material amendments of the Plan must be approved by the Trustees in the manner described above. The Distribution Plan may be terminated at any time by vote of a majority of the Independent Trustees or by vote of a majority of the outstanding voting securities of the relevant class of shares.

During the most recently completed fiscal year, the Distributor and CMD (the former distributor of the Funds’ shares), received distribution and service fees from the Funds for its services as reflected in the following table.

Distribution and Service Fees Paid by the Funds for the Fiscal Year Ended December 31, 2011

Fund	Class A Shares		Class B Shares		Class C Shares		Class R Shares
Columbia Acorn Fund
Distribution and Service Fee	$	9,005,000	$	1,342,000	$	8,052,000		—
Columbia Acorn International
Distribution and Service Fee	$	2,276,000	$	200,000	$	1,067,000	$	4,000
Columbia Acorn USA
Distribution and Service Fee	$	496,000	$	48,000	$	337,000		—
Columbia Acorn Select
Distribution and Service Fee	$	1,180,000	$	375,000	$	821,000		—
Columbia Acorn International Select
Distribution and Service Fee	$	169,000	$	19,000	$	108,000		—
Columbia Acorn European Fund
Distribution and Service Fee	$	100		—	$	20		—
Columbia Acorn Emerging Markets Fund
Distribution and Service Fee	$	170		—	$	80		—
Columbia Thermostat Fund
Distribution and Service Fee	$	136,000	$	160,000	$	236,000		—

Codes of Ethics

The Funds, the Investment Manager and the Distributor have adopted Codes of Ethics pursuant to the requirements of the 1940 Act, including Rule 17j-1 under the 1940 Act. These Codes of Ethics permit personnel subject to the Codes of Ethics to invest in securities, including securities that may be bought or held by the Funds. These Codes of Ethics are included as exhibits to Part C of the Funds’ registration statement. These Codes of Ethics can be reviewed and copied at the SEC’s Public Reference Room and may be obtained by calling the SEC at 202.551.8090; they also are available on the SEC’s website at www.sec.gov, and may be obtained, after paying a duplicating fee, by electronic request to publicinfo@sec.gov or by writing to the SEC’s Public Reference Room, 100 F Street N.E., Washington, D.C. 20549-1520.

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Proxy Voting Policies and Procedures

The Funds have delegated to the Investment Manager the responsibility to vote proxies relating to portfolio securities held by the Funds. In deciding to delegate this responsibility to the Investment Manager, the Board reviewed and approved the policies and procedures adopted by the Investment Manager. These included the procedures that the Investment Manager follows when a vote presents a conflict between the interests of the Funds and their shareholders and the Investment Manager, its affiliates, its other clients or other persons.

The Investment Manager’s policy is that all proxies for Fund securities must be voted in a manner considered by the Investment Manager to be in the best interest of the Funds and their shareholders without regard to any benefit to the Investment Manager, its affiliates, its other clients or other persons. The Investment Manager examines each proposal and votes against the proposal, if, in its judgment, approval or adoption of the proposal would be expected to have an adverse impact on the current or potential market value of the issuer’s securities. The Investment Manager also examines each proposal and votes the proxies against the proposal, if, in its judgment, the proposal would be expected to affect adversely the best interest of the Funds. The Investment Manager determines the best interest of the Funds in light of the potential economic return on the Funds’ investment. The Investment Manager submits an annual report to the Board addressing various proxy voting matters, including, among other matters, votes cast contrary to the Investment Manager’s general voting guidelines, votes involving potential conflicts of interest and significant issues considered by the Investment Manager’s Proxy Voting Committee (Proxy Committee). In certain circumstances, the Investment Manager’s policies permit the Investment Manager to abstain on votes or refrain from voting with respect to shares of foreign stocks.

The Investment Manager seeks to address potential material conflicts of interest by having predetermined voting guidelines and by having each individual stock analyst review and vote each proxy for the stocks that he or she follows. For those proposals that require special consideration or in instances where special circumstances may require varying from the predetermined guideline, the Proxy Committee determines the vote in the best interest of the Funds, without consideration of any benefit to the Investment Manager, its affiliates, its other clients or other persons. The Proxy Committee is composed of representatives of the Investment Manager’s equity investments, equity research, compliance and administration functions. In addition to the responsibilities described above, the Proxy Committee has the responsibility to review, on an annual basis, the Investment Manager’s proxy voting policies to ensure consistency with internal and regulatory agency policies, and to develop additional predetermined voting guidelines to assist in the review of proxy proposals.

The Proxy Committee may vary from a predetermined guideline if it determines that voting on the proposal according to the predetermined guideline would be expected to have an adverse impact on the current or potential market value of the issuer’s securities or to affect adversely the best interest of the client. References to the best interest of a client refer to the interest of the client in terms of the potential economic return on the client’s investment. In determining the vote on any proposal, the Proxy Committee does not consider any benefit other than benefits to the owner of the securities to be voted. A member of the Proxy Committee is prohibited from voting on any proposal for which he or she has a conflict of interest by reason of a direct relationship with the issuer or other party affected by a given proposal. Persons making recommendations to the Proxy Committee or its members are required to disclose to the Committee any relationship with a party making a proposal or other matter known to the person that would create a potential conflict of interest.

The Investment Manager has retained Institutional Shareholder Services (ISS), a third party vendor, to implement its proxy voting process. ISS provides proxy analysis, record keeping services, vote disclosure services and independent proxy voting services.

Information about how the Funds voted proxies relating to portfolio securities during the most recent twelve month period ended June 30 will be available by August 31 of each year free of charge: (i) through the Columbia Funds website, www.columbiamanagement.com, (ii) by calling Columbia Funds at 800.426.3750 or (iii) through the SEC’s website at www.sec.gov. For a copy of the Investment Manager’s policies and procedures that are used to determine how to vote proxies relating to portfolio securities held by the Fund, see Appendix B to this SAI.

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FUND GOVERNANCE

The Board

The following table provides basic information about the Trustees, including their names, the date each was first elected or appointed to office, the principal business occupations of each during at least the last five years and other directorships held. Each Trustee also serves as a trustee of Wanger Advisors Trust, another open-end investment company, the series of which also are managed by the Investment Manager. The mailing address of each Trustee is: c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606.

Independent Trustee Biographical Information

Name, Position Held with the Trust and Age at March 31, 2012	Year First Appointed or Elected to a Board in the Columbia Funds Complex*	Principal Occupation(s) During the Past Five Years	Number of Funds in the Columbia Funds Complex Overseen	Other Directorships Held by Trustee During the Past Five Years
Laura M. Born, 47, Trustee and Chair	2007	Adjunct Assistant Professor of Finance, University of Chicago Booth School of Business; Managing Director — Investment Banking, JP Morgan Chase & Co. (broker-dealer) 2002-2007; prior thereto, associated with JP Morgan as an investment banking professional since 1991.	12	Wanger Advisors Trust
Michelle L. Collins, 52, Trustee	2008	President, Cambium LLC (financial and business advisory firm) since 2007; Advisory Board Member, Svoboda Capital Partners LLC (private equity firm) since 2007; Managing Director, Svoboda Capital Partners LLC, 1998-2006.	12	Wanger Advisors Trust; Integrys Energy Group, Inc. (public utility); Molex, Inc. (electronics components manufacturer); CDW Corporation (provider of technology products and services) until October 2007.

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Name, Position Held with the Trust and Age at March 31, 2012	Year First Appointed or Elected to a Board in the Columbia Funds Complex*	Principal Occupation(s) During the Past Five Years	Number of Funds in the Columbia Funds Complex Overseen	Other Directorships Held by Trustee During the Past Five Years
Maureen M. Culhane, 63, Trustee	2007	Retired. Formerly, Vice President, Goldman Sachs Asset Management, L.P. (investment adviser), 2005-2007, and Vice President (Consultant) — Strategic Relationship Management, Goldman, Sachs & Co., 1999-2005.	12	Wanger Advisors Trust
Margaret M. Eisen, 58, Trustee	2002	Chief Investment Officer, EAM International LLC (corporate finance and asset management) since 2003; Managing Director, CFA Institute, 2005-2008.	12	Wanger Advisors Trust; Antigenics, Inc. (biotechnology and pharmaceuticals) until June 2009.
John C. Heaton, 52, Trustee	2010	Joseph L. Gidwitz Professor of Finance, University of Chicago Booth School of Business since July 2006; James H. Lorie Professor of Finance, University of Chicago Booth School of Business July 2000-July 2006; financial consultant since 2004.	12	Wanger Advisors Trust
Steven N. Kaplan, 52, Trustee and Vice Chair	1999	Neubauer Family Distinguished Service Professor of Entrepreneurship and Finance, University of Chicago Booth School of Business; faculty member of the University of Chicago Booth School of Business since 1988.	12	Wanger Advisors Trust; Accretive Health, Inc. (healthcare management services provider); Morningstar, Inc. (provider of independent investment research).
David J. Rudis, 59, Trustee	2010	National Checking and Debit Executive, and Illinois President, Bank of America, 2007-2009; President, Consumer Banking Group, LaSalle National Bank, 2004-2007.	12	Wanger Advisors Trust

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Name, Position Held with the Trust and Age at March 31, 2012	Year First Appointed or Elected to a Board in the Columbia Funds Complex*	Principal Occupation(s) During the Past Five Years	Number of Funds in the Columbia Funds Complex Overseen	Other Directorships Held by Trustee During the Past Five Years
David B. Small, 55, Trustee	2010	Managing Director, Grosvenor Capital Management, L.P. (investment adviser) since March 1994; Adjunct Associate Professor of Finance, University of Chicago Booth School of Business.	12	Wanger Advisors Trust

Interested Trustee and Trustee Emeritus Biographical Information

Name, Position Held with the Trust and Age at March 31, 2012	Year First Appointed or Elected to a Board in the Columbia Funds Complex*	Principal Occupation(s) During the Past Five Years	Number of Funds in the Columbia Funds Complex Overseen	Other Directorships Held by Trustee During the Past Five Years
Charles P. McQuaid, 58, Trustee and President(1)	1992	President and Chief Investment Officer, CWAM or its predecessors since October 2003; associated with CWAM or its predecessors as an investment professional since 1978.	12	Wanger Advisors Trust
Ralph Wanger, 77, Trustee Emeritus(2)	1970	Founder, CWAM. Formerly, President, Chief Investment Officer and portfolio manager, CWAM or its predecessors, July 1992-September 2003; Director, Wanger Investment Company PLC; Consultant, CWAM or its predecessors, September 2003-September 2005.	12	Wanger Advisors Trust

* Dates prior to April 1992 correspond to the date first elected or appointed as a director or officer of The Acorn Fund Inc., the Trust’s predecessor.

⁽¹⁾  Mr. McQuaid is an “interested person” of the Trust and of the Investment Manager, as defined in the 1940 Act, because he is an officer of the Trust and of the Investment Manager.

⁽²⁾  As permitted under the Trust’s Bylaws, Mr. Wanger serves as Trustee Emeritus of the Trust.

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The Board and its Committees

Responsibilities

The Board has overall management responsibility for the Funds. The Trustees are responsible for supervising and overseeing the management and operation of the Trust. Each Trustee serves a term of unlimited duration, provided that at all times a majority of Trustees has been elected by shareholders. The Trustees appoint their own successors, provided that at least two-thirds of the Trustees, after such appointment, have been elected by shareholders. Shareholders may remove a Trustee, with or without cause, upon the vote of two-thirds of the Trust’s outstanding shares at any meeting called for that purpose. A Trustee may be removed with or without cause upon the vote of a majority of the Trustees.

Leadership Structure

The Board is currently composed of nine Trustees, eight of whom are Independent Trustees and one of whom is an Interested Trustee. In addition to the nine Trustees, Ralph Wanger serves as Trustee Emeritus of the Trust. The Chair of the Board, Laura M. Born, is an Independent Trustee.

Charles P. McQuaid is considered an Interested Trustee because he is an officer of the Funds and of the Investment Manager.

The Board met six times during 2011.

Each trustee was nominated to serve on the Board because of his or her experience, skills and qualifications. See Trustee Experience below. The Board believes that its leadership structure is consistent with industry practices and is appropriate in light of the size of the Trust and the nature and complexity of its business. In particular:

• Board Composition. The Trustees believe that maintaining a Board composed of a super-majority of at least 75% Independent Trustees is appropriate and in the best interest of Fund shareholders. The Trustees also believe that having Mr. McQuaid serve as an Interested Trustee and Mr. Wanger serve as Trustee Emeritus brings management and financial insight that is important to certain of the Board’s decisions and also in the best interest of shareholders.

• Independent Trustee Meetings and Executive Sessions. The Trustees believe that meetings of the Independent Trustees and meetings in executive session help prevent conflicts of interest from occurring and allow the Independent Trustees to deliberate candidly and constructively separately from management in a manner that affords honest disagreement and critical questioning.

• Executive Committee. The Trustees believe that having an Executive Committee allows for expeditious action when the delay necessary to convene a full Board meeting could cause the Funds to miss business opportunities, fail to fulfill regulatory obligations or for other reasons. Actions taken by the Executive Committee generally are ratified by the full Board at its next meeting, ensuring that the Executive Committee acts in the best interests of Fund shareholders and in the absence of conflicts of interest.

The Board has established eight standing committees: the Executive Committee; the Audit Committee; the Valuation Committee; the Contract Committee; the Governance Committee; the Investment Performance Analysis Committee; the Compliance Committee; and the Securities Lending Committee. The Trustees believe

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that the number of standing committees, as well as the composition and scope of activities of each committee, is appropriate. The functions, responsibilities and composition of each committee are set forth below.

Committee	Members	Function	Number of Meetings in 2011
Audit	Michelle L. Collins (chair) Maureen M. Culhane John C. Heaton	Makes recommendations to the Board regarding the selection of independent auditors for the Trust; confers with the independent auditors regarding the scope and results of each audit; oversees the provision of fund accounting services by the Sub-Administrator and of custody services by JPMorgan; and carries out the provisions of its charter.	6
Compliance	Margaret M. Eisen (chair) Michelle L. Collins Steven N. Kaplan David J. Rudis	Provides oversight of the monitoring processes and controls regarding the Trust with respect to legal, regulatory and internal rules, policies, procedures and standards, other than those relating to accounting matters and oversees compliance and risk management by the Funds’ service providers.	5
Contract	David J. Rudis (chair) Laura M. Born Maureen M. Culhane Margaret M. Eisen David B. Small	Makes recommendations to the Board regarding the continuation or amendment of the investment advisory agreements between the Trust and the Investment Manager and other agreements with third party service providers.	11
Executive	Laura M. Born (chair) Steven N. Kaplan Charles P. McQuaid	Exercises powers of the Board during intervals between meetings of the Board, with certain exceptions.	0
Governance	Steven N. Kaplan (chair) Laura M. Born Michelle L. Collins	Makes recommendations to the Board regarding committees of the Board and committee assignments, the composition of the Board, the compensation of the Independent Trustees and candidates for election as Independent Trustees; oversees the process for evaluating the functioning of the Board, including addressing potential conflicts of interest; monitors the performance of the CCO and makes recommendations to the Board regarding the selection and compensation of the CCO; and monitors the performance of counsel to the Funds and the Independent Trustees and makes recommendations to the Independent Trustees regarding the selection of their counsel.	7

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Committee	Members	Function	Number of Meetings in 2011
Investment Performance Analysis	Maureen M. Culhane (chair) John C. Heaton Steven N. Kaplan David B. Small Charles P. McQuaid (ex-officio*)	Monitors and reviews the investment performance of each Fund; develops an appropriate framework for measuring, comparing and assessing Fund performance; provides interpretation of performance information in connection with Fund advisory contracts; makes proposals to the Investment Manager regarding Fund investment objectives, policies and limitations; and acts as a liaison between the Investment Manager and the Board in overseeing and discussing investment-related issues.	5
Valuation	Charles P. McQuaid (chair) Maureen M. Culhane John C. Heaton Laura M. Born (alternate) Michelle L. Collins (alternate) Margaret M. Eisen (alternate) Steven N. Kaplan (alternate) David J. Rudis (alternate) David B. Small (alternate) Bruce H. Lauer (alternate, representative of CWAM)	Determines in good faith the fair valuation of portfolio securities held by any Fund in instances as required by the Trust’s Portfolio Pricing Policy adopted by the Board, and carries out the provisions of its charter.	28
Securities Lending	John C. Heaton (chair) Maureen M. Culhane Margaret M. Eisen Steven N. Kaplan	Meets periodically to consider matters related to the Funds’ securities lending program.	4

* Non-voting member.

The Governance Committee’s policy with respect to considering Trustee candidates recommended by shareholders and the procedures to be followed by shareholders in submitting such recommendations are set forth in the charter. The Governance Committee has stated that the principal criterion for the selection of candidates is their ability to contribute to the overall functioning of the Board and to carry out the responsibilities of the Trustees.

The Governance Committee believes that the Board should be comprised of Trustees who represent a broad cross section of backgrounds, skills and experience, and that each Trustee should generally exhibit stature and experience commensurate with the responsibility of representing the Funds. The Governance Committee periodically reviews the membership of the Board to determine whether it may be appropriate to add individuals with backgrounds or skill sets different from those of the current Trustees. The Governance Committee follows the process it deems appropriate under the circumstances. Generally, the Committee identifies Trustee candidates

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from references provided by the Independent Trustees and others, including nominees recommended by shareholders, and evaluates them through a process of questionnaires and multiple interviews. Through this process, the Governance Committee seeks to identify candidates who meet the particular needs of the Board at the time based on the existing make up of the Board. In addition, counsel to the Independent Trustees analyzes each Independent Trustee candidate to ensure that the candidate meets the independence requirements of the 1940 Act. The Trustees believe that the Board’s process for nominating Trustees effectively produces the best candidates with a diversity of qualities, experience, backgrounds and complementary skills, and that the composition of the Board allows the Board, as a body, to oversee the Funds in a manner that is consistent with the best interests of Fund shareholders.

Although the Investment Manager, the Trustees, or shareholders may submit suggestions for Independent Trustee candidates to the Governance Committee, neither the Governance Committee nor the Independent Trustees as a group shall consider those candidates on a preferential basis as opposed to other possible candidates. Any shareholder may submit the name of a candidate for consideration by the Governance Committee by submitting the recommendation to the Trust’s Secretary. The Secretary will forward any such recommendation to the Chairman of the Governance Committee promptly upon receipt.

Risk Oversight

The Compliance Committee, working with the Funds’ CCO and the Investment Manager, has developed a detailed risk reporting methodology that includes a dashboard report relating to, among other matters, investment risk, credit risk, liquidity risk, counterparty risk, compliance risk and operational risk. Currently, the Investment Manager compiles and monitors relevant risk data or an ongoing basis and the Board and the Compliance Committee receive and review the risk reporting data on a quarterly basis or more frequently if circumstances warrant. The Board will continue to assess the most effective means of implementing this risk oversight process so that it provides the data that is most relevant to the Board in the exercise of its risk oversight role.

The Audit Committee also plays an important role in the Board’s risk oversight. Working with the Funds’ independent registered accountants, the Audit Committee ensures that the Funds’ annual audit scope includes risk-based considerations, such that the auditors consider the risks potentially impacting the audit findings as well as risks to the Funds’ financial position and operations. In addition, the Investment Performance Analysis Committee provides the Board with information relevant to assessing risk oversight by monitoring and reviewing the Funds’ performance metrics, including measurements of risk-adjusted returns, and by regularly conferring with the Investment Manager on performance-related issues. The Securities Lending Committee also receives regular reports from its third-party securities lending consultant regarding the risks associated with the Funds’ securities lending program, including counterparty risk and liquidity.

The Funds’ CCO reports to the Compliance Committee and to the Board at least quarterly regarding compliance and legal risk concerns. In addition to his quarterly reports, the CCO provides an annual report to the Board in accordance with the Funds’ compliance policies and procedures. The CCO regularly discusses relevant compliance and legal risk issues affecting the Funds during meetings with the Independent Trustees and consults with counsel. The CCO updates the Board on the application of the Funds’ compliance policies and procedures and discusses how they mitigate risk. The CCO also reports to the Board immediately regarding any problems associated with the Funds’ compliance policies and procedures that could expose (or that might have the potential to expose) the Funds to material risk.

Trustee Experience

The following is a description of the material attributes, skills and experiences that relate to the suitability of each Trustee to serve on the Board. In addition to these factors, a Trustee is required to possess certain other qualities such as integrity, intelligence, the ability to critically discuss and analyze issues presented to the Board and an understanding of a Trustee’s fiduciary obligations with respect to a registered investment company. The

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Board and Governance Committee believe that each of the Trustees possesses these characteristics in addition to other attributes discussed below.

Laura M. Born. Ms. Born has experience with financial, accounting, regulatory and investment matters as well as an understanding of the securities markets and industry, through her educational background, position for many years as an investment banker at a major investment banking firm and through her position with the University of Chicago, Booth School of Business where she serves as an adjunct assistant professor of finance. Ms. Born has experience analyzing and evaluating financial statements of issuers as a result of her investment banking experience. Ms. Born also is familiar with the functions of the Board and its oversight responsibilities with respect to the Investment Manager and other Fund service providers as a result of her service as an Independent Trustee for the past five years.

Michelle L. Collins. Ms. Collins has investment, business, regulatory and finance experience, having worked as a general partner and managing director of a private equity firm and as principal in an investment banking firm, advising mid-sized growth companies on capital formation and business combinations. She has experience preparing, analyzing and evaluating financial statements, including financial statements of investment advisers and private equity funds. Ms. Collins has served as an audit committee member in many instances and as the audit committee chair of two operating companies. Therefore, the Board believes that Ms. Collins is qualified to serve on the Audit Committee and as Chair of the Audit Committee. Ms. Collins has experience serving as a board member, including as a current director, of public and private operating companies and several non-profit boards. Ms. Collins also has served as an Independent Trustee for the past four years and therefore understands the functions of the Board and its oversight responsibilities with respect to the Investment Manager and other Fund service providers.

Maureen M. Culhane. Ms. Culhane has financial, regulatory and investment experience through her positions as an executive with a large asset management firm, as a vice president of finance and treasurer of a Fortune 100 company, and as a principal of a pension and investment management consulting firm whose clients included, among others, Fortune 100 companies and state pension plans. Ms. Culhane has experience serving as a board member of a public operating company. She also is experienced in Board operations as well as oversight of the Investment Manager and other Fund service providers as a result of her service as an Independent Trustee for the past five years.

Margaret M. Eisen. Ms. Eisen has experience with financial, regulatory and investment matters as a result of her position as a managing director with responsibility for multibillion dollar portfolios of equities, both public and private, at two of the largest corporate pension funds in the United States. She also acquired such experience through her position as a managing director of the CFA Institute, which sets standards for measuring competence and integrity in the fields of portfolio management and investment analysis. Ms. Eisen has experience with board functions through her position as a director of a public operating company. Ms. Eisen also is familiar with the operations of the Board and oversight of the Investment Manager and other Fund service providers through her service as an Independent Trustee for the past ten years.

John C. Heaton. Mr. Heaton is experienced with investment matters as a result of his educational background and academic experience as a professor of finance at the University of Chicago, Booth School of Business. Mr. Heaton has particular experience analyzing investment performance as a result of his financial consulting positions with the investment committees of certain private funds. His consulting experience has focused on matters involving trading litigation, securities pricing, pension fund allocation and fund management. Mr. Heaton also has numerous academic publications in the fields of economics and finance. Mr. Heaton also is familiar with the operations of the Board and oversight of the Investment Manager and other Fund service providers through his service as an Independent Trustee for the past two years.

Steven N. Kaplan. Mr. Kaplan has experience with investment, accounting and finance matters through his educational background and academic position as a professor of finance at the University of Chicago, Booth

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School of Business where he teaches finance and business economics classes to masters and doctoral candidates. Mr. Kaplan has experience with board functions, as well as experience in the investment management industry, through his position as a director of a public operating company that provides independent investment research regarding mutual funds and investment advisers. Mr. Kaplan also is familiar with the operations of the Board and oversight of the Investment Manager and other Fund service providers through his service as an Independent Trustee for the past 13 years.

David J. Rudis. Mr. Rudis has financial, banking, investment, and management experience through more than 30 years of working in the financial services industry. He has held various senior executive positions at regional and national banks, most recently serving as an executive of a Fortune 100 financial institution. Mr. Rudis has familiarity with complex financial, regulatory and banking issues. He also has extensive experience with operations management and business development. Mr. Rudis also is familiar with the operations of the Board and the oversight of the Investment Manager and other Fund service providers through his service as a Trustee for the past year two years.

David B. Small. Mr. Small has experience with investments, investment performance analysis and risk management issues faced by investment advisers and mutual funds, as well as the general operations of these firms, as a result of his position as a portfolio manager and principal of a large registered investment adviser. In his position, Mr. Small has shared management responsibility for portfolio and risk management as well as for evaluation, selection, and monitoring of investment strategies and managers. Prior to his current position, Mr. Small was founder, chief executive officer and chief financial engineer of a software firm specializing in the development of portfolio risk management and trading support software. Mr. Small also is familiar with the operations of the Board and oversight of the Investment Manager and other Fund service providers through his service as an Independent Trustee for the past two years.

Charles P. McQuaid. Mr. McQuaid has investment, business, finance and regulatory experience through his position as president, chief investment officer and director of research of the Investment Manager. Mr. McQuaid has served as an Interested Trustee for 19 years and therefore has significant experience with Board operations and understands the business of the Investment Manager.

Ralph Wanger. Mr. Wanger has investment, business, finance and regulatory experience through his position as founder of the Investment Manager as well as his position as former chief investment officer and portfolio manager of the firm. Mr. Wanger understands Board operations though his service on the Board for over 40 years. Mr. Wanger serves as Trustee Emeritus of the Trust.

Compensation

Trustees are compensated for their services to the Columbia Funds Family on a complex-wide basis, as shown in the table below.

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Independent Trustee Compensation for the Fiscal Year Ended December 31, 2011

Name of Trustee	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn International Select		Columbia Acorn Select		Columbia Thermostat Fund		Columbia Acorn European Fund*		Columbia Acorn Emerging Markets Fund*		Aggregate Compensation from the Trust		Total Compensation from Columbia Funds Complex Paid to Independent Trustees
Laura M. Born	$	134,614	$	38,485	$	20,704	$	3,180	$	14,916	$	1,028	$	4	$	6	$	212,939	$	228,466
Michelle L. Collins	$	96,223	$	27,725	$	14,599	$	2,280	$	10,695	$	742	$	3	$	5	$	152,272	$	163,400
Maureen M. Culhane	$	120,598	$	35,887	$	17,079	$	2,858	$	13,326	$	926	$	4	$	6	$	190,684	$	204,600
Margaret M. Eisen	$	107,796	$	31,932	$	15,267	$	2,555	$	12,120	$	822	$	3	$	5	$	170,499	$	183,000
John C. Heaton(1)	$	87,652	$	25,705	$	12,827	$	2,082	$	9,702	$	670	$	3	$	4	$	138,645	$	148,767
Steven N. Kaplan(2)	$	103,624	$	31,086	$	14,291	$	2,450	$	11,559	$	794	$	3	$	5	$	163,811	$	175,800
Allan B. Muchin(3)	$	79,923	$	23,709	$	11,299	$	1,900	$	9,058	$	607	$	2	$	3	$	126,502	$	135,800
David J. Rudis(4)	$	82,432	$	23,969	$	12,200	$	1,952	$	9,225	$	634	$	2	$	4	$	130,419	$	139,967
David B. Small(5)	$	83,652	$	24,944	$	11,732	$	1,983	$	9,326	$	642	$	2	$	4	$	132,286	$	141,967
James A. Star(6)	$	28,548	$	9,614	$	2,688	$	716	$	3,591	$	212		—		—	$	45,368	$	48,850

* Commenced operations on August 19, 2011.

⁽¹⁾ During the fiscal year ended December 31, 2011, Mr. Heaton deferred $41,570 of his compensation from the Trust and $44,631 of his total compensation from the Columbia Funds Complex through the deferred compensation plan. At December 31, 2011, the value of Mr. Heaton’s account under the plan was $71,226.

⁽²⁾ During the fiscal year ended December 31, 2011, Mr. Kaplan deferred $81,852 of his compensation from the Trust and $87,900 of his total compensation from the Columbia Funds Complex through the deferred compensation plan. At December 31, 2011, the value of Mr. Kaplan’s account under the plan was $844,539.

⁽³⁾ Mr. Muchin served as an Independent Trustee through December 2011.

⁽⁴⁾  During the fiscal year ended December 31, 2011, Mr. Rudis deferred all of his compensation from the Trust and all of his total compensation from the Columbia Funds Complex through the deferred compensation plan. At December 31, 2011, the value of Mr. Rudis’s account under the plan was $133,933.

⁽⁵⁾ During the fiscal year ended December 31, 2011, Mr. Small deferred all of his compensation from the Trust and all of his total compensation from the Columbia Funds Complex through the deferred compensation plan. At December 31, 2011, the value of Mr. Small’s account under the plan was $208,978.

⁽⁶⁾ Mr. Star served as an Independent Trustee through March 24, 2011.

Interested Trustee and Trustee Emeritus Compensation for the Fiscal Year Ended December 31, 2011

Name of Trustee	Columbia Acorn Fund		Columbia Acorn International		Columbia Acorn USA		Columbia Acorn International Select		Columbia Acorn Select		Columbia Thermostat Fund		Columbia Acorn European Fund*		Columbia Acorn Emerging Markets Fund*		Aggregate Compensation from the Trust		Total Compensation from Columbia Funds Complex Paid to Trustees
Charles P. McQuaid	$	0	$	0	$	0	$	0	$	0	$	0	$	0	$	0	$	0	$	0
Ralph Wanger**	$	46,288	$	12,818	$	7,535	$	1,107	$	5,268	$	351	$	1	$	2	$	73,369	$	78,767

* Commenced operations on August 19, 2011.

** During the fiscal year ended December 31, 2011, Mr. Wanger deferred all of his compensation from the Trust and all of his total compensation from the Columbia Funds Complex through the deferred compensation plan. At December 31, 2011, the value of Mr. Wanger’s account under the plan was $596,274.

The officers and Trustees affiliated with the Investment Manager serve without any compensation from the Trust. The Trust and Wanger Advisors Trust have adopted a deferred compensation plan for the Independent Trustees and Mr. Wanger. Under the plan, any Trustee who is not an “interested person” of the Trust or the Investment Manager (participating Trustees) and Mr. Wanger may defer receipt of all or a portion of their compensation as Trustees in order to defer payment of income taxes or for other reasons. The deferred compensation payable to a participating Trustee is credited to a book reserve account as of the business day such compensation would have been paid to such Trustee. The value of a participant’s deferral account at any time is equal to the value that the account would have had if the contributions to the account had been invested in

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Class Z shares of one or more of the Funds or in shares of Columbia Money Market Fund (formerly, the RiverSource Cash Management Fund) — or, prior to May 1, 2010, other affiliated money market funds — as designated by the participant. Upon retirement, the Trustee may receive payments under the plan in a lump sum or in equal annual installments over a period of five years depending on his or her election in accordance with the terms of the plan. If a participating Trustee dies, any amount payable under the plan will be paid to that Trustee’s designated beneficiaries. Each Fund’s obligation to make payments under the plan is a general obligation of that Fund. No Fund is liable for any other Fund’s obligations to make payments under the plan.

The Agreement and Declaration of Trust (the Declaration of Trust) provides that the Trust will indemnify its Trustees and officers against liabilities and expenses incurred in connection with litigation in which they may be involved because of their offices with the Trust but that such indemnification will not relieve any officer or Trustee of any liability to the Trust or its shareholders by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of his or her duties. The Trust, at its expense, provides liability insurance for the benefit of its Trustees and officers.

Beneficial Equity Ownership

The table below shows, for each Trustee, the amount of equity securities of each Fund beneficially owned by the Trustee and the aggregate value of all investments in equity securities of the Columbia Funds Family, including notional amounts through the deferred compensation plan, stated as one of the following ranges: A = $0; B = $1—$10,000; C = $10,001—$50,000; D = $50,001—$100,000; and E = over $100,000.

Certain of the Trustees and officers of the Funds beneficially own more than 1% of the outstanding Class Z shares of certain Funds. For details, see Control Persons and Principal Shareholders — Management Ownership of the Funds.

Independent Trustee Ownership for the Calendar Year Ended December 31, 2011

Name of Trustee	Columbia Acorn Fund	Columbia Acorn International	Columbia Acorn USA	Columbia Acorn International Select	Columbia Acorn Select	Columbia Acorn European Fund	Columbia Acorn Emerging Markets Fund	Columbia Thermostat Fund	Aggregate Dollar Range of Equity Securities in all Funds in  the Columbia Funds Family
Laura M. Born	D	D	A	C	A	A	D	A	E
Michelle L. Collins	C	C	A	A	A	A	A	A	D
Maureen M. Culhane	C	C	A	D	A	C	C	A	E
Margaret M. Eisen	A	C	A	A	A	A	A	A	C
John C. Heaton	D	A	A	A	A	A	A	A	D
Steven N. Kaplan	E	E	E	C	E	A	A	A	E
David J. Rudis	E	A	A	B	A	A	A	A	E
David B. Small	E	D	C	D	D	A	A	A	E

Interested Trustee Ownership for the Calendar Year Ended December 31, 2011

Name of Trustee	Columbia Acorn Fund	Columbia Acorn International	Columbia Acorn USA	Columbia Acorn International Select	Columbia Acorn Select	Columbia Acorn European Fund	Columbia Acorn Emerging Markets Fund	Columbia Thermostat Fund	Aggregate Dollar Range of Equity Securities in all Funds in the Columbia Funds Family
Charles P. McQuaid	E	E	E	E	E	E	E	E	E
Ralph Wanger	E	E	E	E	E	A	A	E	E

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The Officers

The following table provides basic information about the officers of the Trust, other than Mr. McQuaid, including their principal occupations during the past five years, although their specific titles may have varied over the period. The mailing address of each officer is: c/o Columbia Wanger Asset Management, LLC, 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606, except for Messrs. Clarke and DiMaria, whose address is Columbia Management Investment Advisers, LLC, 225 Franklin Street, Boston, MA 02110, and Messrs. Plummer and Petersen, whose address is Ameriprise Financial, Inc., 5060 Ameriprise Financial Center, Minneapolis, MN 55474.

Officer Biographical Information

Name and Age at March 31, 2012	Position with the Trust	Year First Appointed or Elected to Office	Principal Occupation(s) During the Past Five Years
Ben Andrews, 46	Vice President	2004	Portfolio manager and/or analyst, CWAM or its predecessors since 1998; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2004.
Robert A. Chalupnik, 46	Vice President	2011	Portfolio manager and/or analyst, CWAM or its predecessors since 1998; Vice President Columbia Acorn Trust and Wanger Advisors Trust since May 2011.
Michael G. Clarke, 42	Assistant Treasurer	2004	Vice President, Columbia Management since May 2010; Managing Director of Fund Administration, Columbia Management Advisors, LLC, from September 2004 to April 2010; Senior officer, Columbia Funds and affiliated funds since 2002.
Joseph F. DiMaria, 43	Assistant Treasurer	2010	Vice President, Mutual Fund Administration, Columbia Management since May 2010; Director of Fund Administration, Columbia Management Advisors, LLC from January 2006 to April 2010.
P. Zachary Egan, 43	Vice President	2003	Director of International Research, CWAM since December 2004; Vice President, Columbia Acorn Trust since 2003 and Wanger Advisors Trust since 2007; portfolio manager and/or analyst, CWAM or its predecessors since 1999.

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Name and Age at March 31, 2012	Position with the Trust	Year First Appointed or Elected to Office	Principal Occupation(s) During the Past Five Years
Fritz Kaegi, 40	Vice President	2011	Portfolio manager and/or analyst, CWAM or its predecessors since 2004; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2011.
John Kunka, 41	Assistant Treasurer	2006	Director of Accounting and Operations, CWAM since May 2006.
Stephen Kusmierczak, 44	Vice President	2011	Portfolio manager and/or analyst, CWAM or its predecessors since 2001; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2011.
Joseph C. LaPalm, 42	Vice President	2006	Chief Compliance Officer, CWAM since 2005.
Bruce H. Lauer, 54	Vice President, Secretary and Treasurer	1995	Chief Operating Officer, CWAM or its predecessors since April 2000; Vice President, Treasurer and Secretary, Columbia Acorn Trust and Wanger Advisors Trust since 1995; Director, Wanger Investment Company PLC; formerly, Director, Banc of America Capital Management (Ireland) Ltd.; and formerly, Director, Bank of America Global Liquidity Funds, PLC.
Louis J. Mendes III, 47	Vice President	2003	Portfolio manager and/or analyst, CWAM or its predecessors since 2001; Vice President, Columbia Acorn Trust since 2003 and Wanger Advisors Trust since 2005.
Robert A. Mohn, 50	Vice President	1997	Director of Domestic Research, CWAM or its predecessors since March 2004; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 1997; portfolio manager and/or analyst, CWAM or its predecessors since 1992. Mr. Mohn served as Principal Executive Officer of the Funds during Mr. McQuaid’s sabbatical from January 14 through March 31, 2011.

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Name and Age at March 31, 2012	Position with the Trust	Year First Appointed or Elected to Office	Principal Occupation(s) During the Past Five Years
Christopher J. Olson, 47	Vice President	2001	Portfolio manager and/or analyst, CWAM or its predecessors since January 2001; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2001.
Christopher O. Petersen, 42	Assistant Secretary	2010	Vice President and Chief Counsel, Ameriprise Financial since January 2010 (formerly Vice President and Group Counsel or Counsel from April 2004 to January 2010); officer, Columbia Funds and affiliated funds since 2007.
Scott R. Plummer, 52	Assistant Secretary	2010	Senior Vice President, Chief Legal Officer and Assistant Secretary, Columbia Management (or its predecessors) since June 2005; Senior Vice President and Lead Chief Counsel — Asset Management, Ameriprise Financial since February 2012 (previously Vice President and Lead Chief Counsel — Asset Management, from 2010 to January 2012, and Vice President and Chief Counsel — Asset Management, from 2005 to April 2010; Vice President, Chief Counsel and Assistant Secretary, the Distributor (or its predecessors) since 2008; Vice President, General Counsel and Secretary, Ameriprise Certificate Company since 2005; Chief Counsel, RiverSource Distributors, Inc. from 2006 to 2010; senior officer, Columbia Funds and affiliated funds since 2006.
Robert P. Scales, 59	Chief Compliance Officer, Chief Legal Officer, Senior Vice President and General Counsel	2004	Chief Compliance Officer, Chief Legal Officer, Senior Vice President and General Counsel, Columbia Acorn Trust and Wanger Advisors Trust since 2004.

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Name and Age at March 31, 2012	Position with the Trust	Year First Appointed or Elected to Office	Principal Occupation(s) During the Past Five Years
Andreas Waldburg-Wolfegg, 46	Vice President	2011	Portfolio manager and/or analyst, CWAM or its predecessors since 2002; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2011.
Linda Roth-Wiszowaty, 41	Assistant Secretary	2006	Business support analyst, CWAM since April 2007; prior thereto, executive administrator, CWAM or its predecessors, and executive assistant to the Chief Operating Officer, CWAM or its predecessors.

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BROKERAGE ALLOCATION AND OTHER PRACTICES

The Investment Manager places the orders for the purchase and sale of portfolio securities and options and futures contracts for the Funds, subject to the oversight of the Board. In doing so, it seeks to place buy and sell orders in a manner that is fair and reasonable to each Fund. The Investment Manager’s overriding objective in selecting broker-dealers to effect portfolio transactions is to seek the best combination of net price and execution, provided that the Investment Manager may occasionally pay higher commissions to obtain research products and services as described below. The best net price, giving effect to brokerage commissions, if any, and other transaction costs, is a significant factor in this decision; however, a number of other judgmental factors may also enter into the analysis. These factors include the Investment Manager’s knowledge of negotiated commission rates currently available and other current transaction costs; the nature of the security being purchased or sold; the size and type of the transaction; the desired timing of the transaction; the actual and expected activity in the market for the particular security; confidentiality concerns; the execution, clearance and settlement capabilities of the broker-dealer selected and others considered; the Investment Manager’s knowledge of the reliability, reputation and financial stability of the broker-dealer selected and such other broker-dealers; evaluation of competing markets, including exchanges, over-the-counter markets, electronic communications networks (ECNs) or other alternative trading facilities; the broker-dealer’s responsiveness to the Investment Manager; the Investment Manager’s knowledge of actual or apparent operation problems of any broker-dealer; and the value of any research products or services provided by the broker-dealer. With respect to a Fund’s purchases and sales of portfolio securities transacted with a broker-dealer on a net basis, the Investment Manager may also consider the part, if any, played by the broker-dealer in bringing the securities to the Investment Manager’s attention, including investment research related to the securities.

Recognizing the value of those factors, the Investment Manager will use its best judgment in evaluating the terms of a transaction, which may result in a Fund paying a brokerage commission in excess of what another broker-dealer might have charged for effecting the same transaction. The Investment Manager has discretion for all trades of the Funds, and periodically reviews and modifies, as appropriate, its trading, as well as the general level of brokerage commissions paid by the Funds. Evaluations of the reasonableness of brokerage commissions, based on the factors described in the preceding paragraph, are made by the Investment Manager’s trading personnel while effecting portfolio transactions. Reports on brokerage commissions are provided at least annually to the Board.

The Investment Manager maintains and periodically updates a list of approved broker-dealers that, in the Investment Manager’s judgment, are generally capable of providing best price and execution and are financially stable. The Investment Manager’s traders are directed to use only broker-dealers on the approved list. The Investment Manager may place trades for the Funds through a registered broker-dealer that is an affiliate of the Investment Manager — including, in the case of agency transactions, broker-dealers and financial institutions that are affiliated with Ameriprise Financial — pursuant to procedures adopted by the Board pursuant to Rule 17e-1 under the 1940 Act. Such trades, for which the affiliate would receive a commission, will only be effected consistent with the Investment Manager’s obligation to seek best execution for its clients, and in accordance with the Funds’ Rule 17e-1 procedures.

Under certain circumstances, a Fund may buy securities from a member of an underwriting syndicate in which an affiliate of Ameriprise Financial is a member. The Board has approved procedures pursuant to Rule 10f-3 under the 1940 Act for the Funds, and the Investment Management intends to comply with these procedures in connection with any purchase of securities that may be subject to Rule 10f-3.

The Investment Manager’s decisions for a Fund are not always made independently from those for other Funds or accounts advised or managed by the Investment Manager. When a purchase or sale of the same security is made at substantially the same time on behalf of one or more of the Funds and/or another account, the transaction will be allocated in a manner which the Investment Manager believes to be equitable to the Funds and such other account(s). In some instances, this investment procedure may adversely affect the price paid or

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received by a Fund or the size of the position obtained or sold by the Fund. It is the Investment Manager’s practice, when feasible, and to the extent permitted by law, to aggregate for execution as a single transaction orders for the purchase or sale of a particular security, with the same terms and conditions, for the accounts of its clients, including the Funds, in order to seek a lower commission or more advantageous net price. All Funds and other clients participating in the aggregated execution receive the same execution price, and transaction costs are shared pro-rata, whenever possible.

Investment Research Products and Services Furnished by Broker-Dealers

The Investment Manager engages in the long-standing practice in the asset management industry of acquiring research and brokerage products and services (together, “research products”) from broker-dealer firms in return for directing trades for the Funds and other clients to those firms. In effect, the Investment Manager is using the commission dollars paid by its clients, including the Funds, to pay for these research products. The asset management industry uses the term “soft dollars” to refer to this industry practice. The Board reviews the Investment Manager’s soft dollar practices at least annually.

The Investment Manager uses soft dollars to acquire two types of research products: (i) proprietary research created by broker-dealer firms executing trades for the Funds and other clients of the Investment Manager; and (ii) research created by third parties that is supplied to the Investment Manager through executing broker-dealer firms (or other broker-dealers who “step in” to a transaction and receive a portion of the brokerage commission for the trade). These research products consist primarily of traditional research reports, recommendations and similar materials produced by the in-house research staffs of broker-dealer firms. It includes evaluations and recommendations of specific companies or industry groups, as well as analyses of general economic and market conditions and trends, market data, contacts and other related information and assistance. Research products also may include the arranging of meetings with management of companies and the provision of access to consultants who supply research information. Some research products may be used for both investment decision-making and non-investment-decision-making purposes (referred to in the asset management industry as “mixed use” products). While the Investment Manager currently does not obtain mixed use products using soft dollars, the Investment Manager has procedures in place to assure that to the extent it acquires mixed use products, Fund commissions are used only to pay for the investment decision-making portion of the mixed use products. In the case of third party research, the third party is paid by the broker-dealer and not by the Investment Manager.

Soft dollar research products are useful to the Investment Manager for a number of reasons, including that, in certain instances, the broker-dealers utilized by the Investment Manager may follow a different universe of securities issuers and other matters than those followed by the Investment Manager’s research analysts. In addition, such research products can provide the Investment Manager with a different perspective on financial markets, even if the research obtained relates to securities followed by the Investment Manager. Research products that are provided to the Investment Manager by broker-dealers are available for the benefit of all clients advised by the Investment Manager, including the Funds. In some cases, a research product may be available only from the broker-dealer providing it. In other cases, a research product may be obtainable from alternative sources. The Investment Manager is of the opinion that soft dollar research products are beneficial in supplementing its research and analysis and may therefore benefit the Funds by improving the quality of the investment advice provided to them.

The Investment Manager has a duty to seek the best combination of net price and execution, and thus faces a potential conflict of interest with this duty when it uses soft dollars to obtain research products. This conflict exists because the Investment Manager pays for the research products using brokerage commissions paid by the Funds and does not pay for the products using its own assets. The Investment Manager is able to use the research products in managing its client accounts without paying cash (“hard dollars”) for the product, which reduces the Investment Manager’s cost of managing the accounts to the extent the Investment Manager would have bought such products had they not been provided. The Investment Manager does not reduce the advisory fees paid by the Funds commensurately with its receipt of soft dollar research products.

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The practice of using soft dollars to obtain research products and services is explicitly sanctioned by a provision of the 1934 Act that creates a “safe harbor” for soft dollar transactions conducted in a specified manner. Under Section 28(e) of the 1934 Act, the Investment Manager shall not be “deemed to have acted unlawfully or to have breached its fiduciary duty” solely because under certain circumstances it has caused a Fund or other client to pay a higher commission than the lowest available. To obtain the benefit of Section 28(e), the Investment Manager must make a good faith determination that the commissions paid are “reasonable in relation to the value of the brokerage and research services provided by such member or broker-dealer, viewed in terms of either that particular transaction or his overall responsibilities with respect to the accounts as to which he exercises investment discretion.” Within the safe harbor of Section 28(e), the Investment Manager may cause a Fund to pay a brokerage commission in a soft dollar trade in excess of that which another broker-dealer might have charged for the same transaction.

Moreover, under Section 28(e), the Investment Manager is not required to use a research product only in managing the accounts that generated the trade. Thus, a Fund that generates the brokerage commission used to acquire a research product will not necessarily benefit directly from that product; in effect, the Fund may be cross-subsidizing the Investment Manager’s management of the other Funds and other clients that do benefit directly from the product. Conversely, the Fund may benefit from research products received by the Investment Manager through the placement of transactions for other Funds or other clients of the Investment Manager. Although it is inherently difficult if not impossible to document, the Investment Manager believes that over time each Fund benefits because the cross-subsidization of the Investment Manager’s receipt of research products improves the overall quality of the Investment Manager’s investment advice.

Some broker-dealers may indicate that the provision of research products is dependent upon the generation of certain specified levels of commission by the Funds. The Investment Manager’s research analysts periodically rate the quality of research products provided by various broker-dealer firms. Based on these evaluations, the Investment Manager develops target levels of commission dollars on a firm-by-firm basis. The Investment Manager attempts to direct trades to each individual approved broker-dealer firm to meet those targets. The targets that the Investment Manager establishes for various broker-dealers for both proprietary and for third party research typically reflect discussions that the Investment Manager has with the broker-dealer providing the research regarding the level of commissions it expects to receive for the research. However, those targets, which are established on a calendar year basis, are not binding commitments, and the Investment Manager does not agree to direct a minimum amount of commissions to any broker-dealer for soft dollar research. In setting those targets, the Investment Manager makes a determination that the value of the research is reasonably commensurate with the cost of acquiring it. The Investment Manager will receive the research whether or not commissions directed to the applicable broker-dealer are less than, equal to or in excess of the target. The Investment Manager generally will carry over target shortages and excesses to the next year’s target. The Investment Manager believes that this practice reduces the conflicts of interest associated with soft dollar transactions, since the Investment Manager can meet the non-binding expectations of broker-dealers providing soft dollar research over flexible time periods. In the case of third party research, the third party is paid by the broker-dealer and not by the Investment Manager.

In certain instances, the Investment Manager pays for research products with commissions on trades executed through ECNs. The Investment Manager may direct a portion of the commissions from these trades to an introducing broker through a Commission Sharing Agreement (CSA). Where the Investment Manager has executed a CSA with an introducing broker-dealer, the Investment Manager will place a trade with the ECN, and pay the negotiated commission to the ECN. The ECN will then credit a negotiated portion of the commission to the introducing broker-dealer as requested by the Investment Manager for the purpose of funding a pool to be used to pay for research products or services received by the Investment Manager from other third parties. In addition, the ECN will credit a further portion of the commission negotiated by the ECN and the introducing broker-dealer to the introducing broker-dealer for its services in administrating the CSA. The ECN makes periodic lumpsum payments to the introducing broker-dealer. CSAs are a permitted form of soft dollar transaction under Section 28(e) of the 1934 Act.

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In certain cases, the Investment Manager will direct a trade to one broker-dealer with the instruction that it execute the trade and pay over a portion of the commission from the trade to another broker-dealer who provides the Investment Manager with a soft dollar research product or service. The broker-dealer executing the trade “steps out” of a portion of the commission in favor of the other broker-dealer providing the research product. The Investment Manager may engage in step out transactions in order to direct soft dollar commissions to a broker-dealer which provides research but may not be able to provide best execution. Broker-dealers that receive step out commissions typically are brokers providing third party soft dollar research that is not available on by paying cash for the research. The Investment Manager does not engage in step out transactions as a manner of compensating broker-dealers that sell shares of investment companies managed by the Investment Manager.

The Trust’s purchases and sales of securities not traded on securities exchanges generally are placed by the Investment Manager with market makers for those securities on a net basis, without any brokerage commissions being paid by the Trust. Net trading does involve, however, transaction costs. Included in the price paid to an underwriter of portfolio securities is the spread between the price paid by the underwriter to the issuer and the price paid by the purchasers. Each Fund’s purchases and sales of portfolio securities in the over-the-counter market usually are transacted with a broker-dealer on a net basis without any brokerage commission being paid by such Fund, but do reflect the spread between the bid and asked prices. The Investment Manager may also transact purchases of some portfolio securities directly with the issuers.

Brokerage Commissions

The following table describes the amounts of brokerage commissions paid by the Funds during their three most recently completed fiscal years. In certain instances the Funds may pay brokerage commissions to broker-dealers that are affiliates of Ameriprise Financial. As indicated above, all such transactions involving the payment of brokerage commissions to affiliates are done in compliance with Rule 17e-1 under the 1940 Act.

Aggregate Brokerage Commissions Paid by the Funds

Fund	Fiscal Year  Ended December 31, 2011		Fiscal Year  Ended December 31, 2010			Fiscal Year  Ended December 31, 2009
Columbia Acorn Fund	$	9,717,000	$	16,337,000		$	12,833,000
Columbia Acorn International	$	5,779,000	$	7,526,000		$	3,941,000
Columbia Acorn USA	$	1,184,000	$	1,785,000		$	1,388,000
Columbia Acorn Select	$	1,738,000	$	2,777,000		$	1,921,000
Columbia Acorn International Select	$	537,000	$	535,000		$	718,000
Columbia Acorn European Fund	$	2,000	$	N/A	*	$	N/A	*
Columbia Acorn Emerging Markets Fund	$	4,000	$	N/A	*	$	N/A	*
Columbia Thermostat Fund	$	0	$	0		$	0

* Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund commenced operations on August 19, 2011.

The Funds paid no brokerage commissions to affiliated broker-dealers for the fiscal years ended December 31, 2011, December 31, 2010 and December 31, 2009.

Directed Brokerage

The Funds or the Investment Manager, through an agreement or understanding with a broker-dealer, or otherwise through an internal allocation procedure, may direct, subject to applicable legal requirements, the Funds’ brokerage transactions to a broker-dealer because of the research services it provides the Funds or the Investment Manager.

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During the fiscal year ended December 31, 2011, the Funds directed brokerage transactions in the dollar amounts shown in the following table, which also shows the commissions paid to broker-dealers in connection with those transactions.

	Directed Transactions		Directed Commissions
Columbia Acorn Fund	$	5,636,137,000	$	5,784,000
Columbia Acorn International	$	2,937,511,000	$	4,019,000
Columbia Acorn USA	$	644,531,000	$	734,000
Columbia Acorn Select	$	1,066,998,000	$	1,202,000
Columbia Acorn International Select	$	349,077,000	$	432,000
Columbia Acorn European Fund	$	1,867,000	$	2,000
Columbia Acorn Emerging Markets Fund	$	2,114,000	$	2,000
Columbia Thermostat Fund	$	0	$	0

Securities of Regular Broker-Dealers

In certain cases, the Funds, as part of their principal investment strategies, or otherwise as a permissible investment, will invest in the common stock or debt obligations of the regular broker-dealers that the Investment Manager uses to transact brokerage for the Columbia Funds Family.

As of December 31, 2011, the Funds did not own securities of any “regular broker or dealer” or its parents, as defined in Rule 10b-1 under the 1940 Act.

Additional Shareholder Servicing Payments

The Transfer Agent, the Distributor and the Investment Manager may pay significant amounts to selling agents, including other Ameriprise Financial affiliates, for providing the types of services that would typically be provided directly by a mutual fund’s transfer agent. The level of payments made to selling agents may vary. A number of factors may be considered in determining payments to a selling agent, including, without limitation, the nature of the services provided to shareholders or retirement plan participants that invest in the Funds through retirement plans. These services may include sub-accounting, sub-transfer agency, participant recordkeeping, shareholder or participant reporting, shareholder or participant transaction processing, keeping shareholder records, preparing account statements and/or the provision of call center support and other customer services (Additional Shareholder Services). Payments for Additional Shareholder Services vary by selling agent but generally are not expected, with certain limited exceptions, to exceed 0.40% of the average aggregate value of a Fund’s shares on an annual basis. Subject to certain limitations, the Board has authorized the Funds to reimburse payments made by the Transfer Agent to such selling agents, including Ameriprise Financial affiliates, for Additional Shareholder Services in amounts that vary with the type of intermediary and the type of Additional Shareholder Services provided. The amounts payable to such selling agents for Additional Shareholder Services in excess of the amounts reimbursed by the Fund are borne by the Distributor or other Ameriprise Financial affiliates.

The Funds also may make additional payments to selling agents that charge networking fees for certain services provided in connection with the maintenance of shareholder accounts through the NSCC.

In addition, the Distributor and other Ameriprise Financial affiliates may make lump sum payments to selected selling agents receiving shareholder servicing payments in reimbursement of printing costs for literature for participants, account maintenance fees or fees for establishment of the Funds on the selling agent’s system or other similar services.

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As of the date of this SAI, the Distributor and/or other Ameriprise Financial affiliates had agreed to make shareholder servicing payments with respect to the Funds to the selling agents or their affiliates shown below.

Recipients of Shareholder Servicing Payments relating to the Funds from the Distributor and/or other Ameriprise Financial affiliates

•   ADP Broker-Dealer, Inc. •   American United Life Insurance Co. •   Ameriprise Financial Services, Inc. •   Ascensus, Inc. •   AXA Advisors •   Bank of America, N.A. •   Benefit Plan Administrators •   Benefit Trust •   Charles Schwab & Co., Inc. •   Charles Schwab Trust Co. •   Davenport & Company •   City National Bank •   CPI Qualified Plan Consultants, Inc. •   Daily Access Concepts, Inc.

•   Mid Atlantic Capital Corporation •   Minnesota Life Insurance Co. •   Morgan Stanley Smith Barney •   Morgan Keegan & Company •   National Financial Services •   Newport Retirement Services, Inc. •   New York State Deferred Compensation Plan •   NYLife Distributors LLC •   Oppenheimer •   Plan Administrators, Inc. •   PNC Bank •   Princeton Retirement Group •   Principal Life Insurance Company of America •   Prudential Insurance Company of America

•   Digital Retirement Solutions •   Edward D. Jones & Co., LP •   ExpertPlan •   Fidelity Investments Institutional Operations Co. •   First National Bank of Omaha •   Guardian Life and Annuity Company Inc. •   Genworth Life and Annuity Insurance Company •   GWFS Equities, Inc. •   Hartford Life Insurance Company •   Hartford Securities Distribution •   Hewitt Associates LLC •   ICMA Retirement Corporation •   ING Life Insurance and Annuity Company •   ING Institutional Plan Services, LLP •   Janney Montgomery Scott, Inc. •   JJB Hillard Lyons •   John Hancock Life Insurance Company (USA) •   John Hancock Life Insurance Company of New York •   JP Morgan Retirement Plan Services LLC •   Lincoln Retirement Services •   LPL Financial Corporation •   Marshall & Illsley Trust Company •   Massachusetts Mutual Life Insurance Company •   Matrix Settlement & Clearance Services •   Mercer HR Services, LLC •   Merrill Lynch Life Insurance Company •   Merrill Lynch, Pierce, Fenner & Smith Incorporated

•   Prudential Retirement Insurance & Annuity Company •   Pershing LLC •   Raymond James & Associates •   RBC Dain Rauscher •   Reliance Trust •   Robert W. Baird & Co., Inc. •   Scott & Stringfellow, LLC •   Standard Insurance Company •   Stifel Nicolaus & Co. •   Deferred Compensation Board of the State of New York •   TD Ameritrade Clearing, Inc. •   TD Ameritrade Trust Company •   The Retirement Plan Company •   Teachers Insurance and Annuity Association of America •   T. Rowe Price Group, Inc. •   UBS Financial •   Unified Trust Company, N.A. •   Upromise Investments, Inc. •   USAA Investment Management Co •   Vanguard Group, Inc. •   VALIC Retirement Services Company •   Wells Fargo Bank, N.A. •   Wells Fargo Funds Management, LLC •   Wilmington Trust Company •   Wilmington Trust Retirement & Institutional Services Company

The Distributor and/or other Ameriprise Financial affiliates may enter into similar arrangements with other selling agents from time to time. Therefore, the preceding list is subject to change at any time without notice.

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Additional Selling Agent Payments

Selling agents may receive different commissions, sales charge reallowances and other payments with respect to sales of different classes of shares of the Funds. These other payments may include servicing payments to retirement plan administrators and other institutions at rates up to those described above under Brokerage Allocation and Other Practices — Additional Shareholder Servicing Payments.

The Distributor and other Ameriprise Financial affiliates may pay additional compensation to selected selling agents, including other Ameriprise Financial affiliates, under the categories described below. These categories are not mutually exclusive, and a single selling agent may receive payments under all categories. A selling agent also may receive payments described above in Brokerage Allocation and Other Practices — Additional Shareholder Servicing Payments. These payments may create an incentive for a selling agent or its representatives to recommend or offer shares of a Fund to its customers. The amount of payments made to selling agents may vary. In determining the amount of payments to be made, the Distributor and other Ameriprise Financial affiliates may consider a number of factors, including, without limitation, asset mix and length or relationship with the selling agent, the size of the customer/shareholder base of the selling agent, the manner in which customers of the selling agent make investments in the Funds, the nature and scope of marketing support or services provided by the selling agent (as described more fully below) and the costs incurred by the selling agent in connection with maintaining the infrastructure necessary or desirable to support investments in the Funds.

These additional payments by the Distributor and other Ameriprise Financial affiliates are made pursuant to agreements between the Distributor and other Ameriprise Financial affiliates and selling agents, and do not change the price paid by investors for the purchase of a share, the amount a Fund will receive as proceeds from such sales or the distribution fees and expenses paid by the Fund as shown under the heading Fees and Expenses in the Fund’s prospectuses.

Marketing Support Payments

The Distributor and its affiliates may make payments, from their own resources, to certain selling agents, including other Ameriprise Financial affiliates, for marketing support services relating to the Columbia Funds, including, but not limited to, business planning assistance, educating selling agent personnel about the Funds and shareholder financial planning needs, placement on the selling agent’s preferred or recommended fund list or otherwise identifying the Funds as being part of a complex to be accorded a higher degree of marketing support than complexes not making such payments, access to sales meetings, sales representatives and management representatives of the selling agent, client servicing and systems infrastructure support. These payments are generally based upon one or more of the following factors: average net assets of the Columbia Funds distributed by the Distributor attributable to that selling agent, gross sales of the Columbia Funds distributed by the Distributor attributable to that selling agent, reimbursement of ticket charges (fees that a selling agent firm charges its representatives for effecting transactions in Fund shares) or a negotiated lump sum payment.

While the financial arrangements may vary for each selling agent, the marketing support payments to each selling agent generally are expected to be between 0.05% and 0.50% on an annual basis for payments based on average net assets of the Funds attributable to the selling agent, and between 0.05% and 0.25% on an annual basis for firms receiving a payment based on gross sales of the Columbia Funds attributable to the selling agent. The Distributor and other Ameriprise Financial affiliates may make payments in materially larger amounts or on a basis materially different from those described above when dealing with certain selling agents. Such increased payments may enable such selling agents to offset credits that they may provide to their customers.

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As of April 2012, the Distributor, the Investment Manager or their affiliates had agreed to make marketing support payments relating to the Funds to the selling agents or their affiliates shown below.

Recipients of Marketing Support Payments relating to the Funds from the Distributor and/or other Ameriprise Financial affiliates

•   AIG Advisor Group •   Ameriprise Financial Services, Inc. •   AXA Advisors, LLC •   Commonwealth Financial Network •   Fidelity Brokerage Services, Inc. •   J.J.B. Hilliard, W.L. Lyons, Inc. •   J.P. Morgan Chase Clearing Corp. •   Lincoln Financial Advisors Corp. •   Linsco/Private Ledger Corp. •   Morgan Stanley Smith Barney •   Merrill Lynch Life Insurance Company •   Merrill Lynch, Pierce, Fenner & Smith Incorporated

•   Oppenheimer •   Pershing LLC •   Prudential Investment Management Services, LLC •   Raymond James & Associates, Inc. •   Raymond James Financial Services, Inc. •   RBC Dain Rauscher •   Securities America •   UBS Financial Services Inc. •   Wells Fargo Advisors •   Wells Fargo Investments, LLC •   Vanguard Marketing Corp

The Distributor, the Investment Manager and/or their affiliates may enter into similar arrangements with other selling agents from time to time. Therefore, the preceding list is subject to change at any time without notice.

Other Payments

From time to time, the Distributor, from its own resources, may provide additional compensation to certain selling agents that sell or arrange for the sale of shares of the Funds to the extent not prohibited by laws or the rules of any self-regulatory agency, such as the Financial Industry Regulatory Authority (FINRA). Such compensation provided by the Distributor may include financial assistance to selling agents that enable the Distributor to participate in and/or present at selling agent-sponsored conferences or seminars, sales or training programs for invited registered representatives and other selling agent employees, selling agent entertainment and other selling agent-sponsored events, and travel expenses, including lodging incurred by registered representatives and other employees in connection with prospecting, retention and due diligence trips. The Distributor makes payments for entertainment events it deems appropriate, subject to the Distributor’s internal guidelines and applicable law. These payments may vary depending upon the nature of the event.

Your selling agent may charge you fees or commissions in addition to those disclosed in this SAI. You should consult with your selling agent and review carefully any disclosure your selling agent provides regarding its services and compensation. Depending on the financial arrangement in place at any particular time, a selling agent and its financial consultants may have a financial incentive for recommending a particular fund or a particular share class over other funds or share classes. See Investment Advisory and Other Services — Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest for more information.

Performance Disclosure

Effective beginning with performance reporting for the December 31, 2011 year end, in presenting performance information for newer share classes, if any, of a Fund, the Fund typically includes, for periods prior to the offering of such share classes, the performance of the Fund’s oldest share class (except as otherwise disclosed), adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable, based on the expense ratios of those share classes for the Fund’s most recently completed fiscal year for which data was available at December 31, 2011 or, for funds and classes first offered after January 1, 2011, the expected expense differential at the time the newer share class is first offered. Actual expense differentials across classes will vary over time. The performance of the Fund’s newer share classes would have been substantially similar to the performance of the Fund’s oldest share class because all share classes of a Fund are

invested in the same portfolio of securities, and would have differed only to the extent that the classes do not have the same sales charges and/or expenses (although differences in expenses between share classes may change over time).

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CAPITAL STOCK AND OTHER SECURITIES

Description of the Trust’s Shares

The Funds offer shares in the classes shown in the table below. Subject to certain limited exceptions discussed in each Fund’s prospectuses, a Fund or share class may no longer be accepting new investments from current shareholders or prospective investors. A Fund may, at any time and without notice, offer or stop offering any share class to the general public for investment.

The Trust’s Declaration of Trust permits it to issue an unlimited number of full and fractional shares of beneficial interest of each Fund, without par value, and to divide or combine the shares of any series into a greater or lesser number of shares of that Fund without thereby changing the proportionate beneficial interests in that Fund and to divide such shares into classes. Each share of a class of a Fund represents an equal proportional interest in that Fund with each other share in the same class and is entitled to such distributions out of the income earned on the assets belonging to that Fund as are declared in the discretion of the Board. However, different share classes of a Fund pay different distribution amounts because each share class has different expenses. Each time a distribution is made, the net asset value (NAV) per share of the share class is reduced by the amount of the distribution.

Share Classes Offered by the Funds

Fund	Class A	Class B*	Class C	Class I	Class R	Class R4	Class R5**	Class Y	Class Z***
Columbia Acorn Fund	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn International	ü	ü	ü	ü	ü	ü	ü	ü	ü
Columbia Acorn USA	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn Select	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn International Select	ü	ü	ü	ü	—	ü	ü	ü	ü
Columbia Acorn European Fund	ü	—	ü	ü	—	—	ü	—	ü
Columbia Acorn Emerging Markets Fund	ü	—	ü	ü	—	ü	ü	—	ü
Columbia Thermostat Fund	ü	ü	ü	—	—	ü	ü	ü	ü

* Class B shares of the Funds are closed to new investments by new and existing investors. See the Funds’ prospectuses for details.

** Shareholders with Class R5 shares accounts funded before November 8, 2012 who do not satisfy the current eligibility criteria for Class R5 shares may not establish new Class R5 accounts but may continue to make additional purchases of Class R5 shares in existing accounts. In addition, investment advisory programs and similar programs that opened a Class R5 account as of May 1, 2010, and continuously hold Class R5 shares in such account after such date, may generally not only continue to make additional purchases of Class R5 shares but also open new Class R5 accounts and add new shareholders in the program. See the Funds’ prospectuses and Appendix S to this SAI for details.

*** Effective March 29, 2013, selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that have been given specific written notice from the Transfer Agent of the termination of their eligibility for new purchases of Class Z shares and omnibus retirement plans will not be permitted to establish new Class Z accounts, subject to certain exceptions. Omnibus retirement plans that opened and, subject to exceptions, funded a Class Z account as of close of business on March 28, 2013, and continuously hold Class Z shares in such account after such date, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. In certain circumstances and in the sole discretion of the Distributor, omnibus retirement plans affiliated with a grandfathered plan may also open new Class Z accounts after March 28, 2013. Accounts of selling agents (other than omnibus retirement plans) that clear Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms will not be permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions) after March 28, 2013. See the Funds’ prospectuses and Appendix S to this SAI for details.

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Restrictions on Holding or Disposing of Shares

There are no restrictions on the right of shareholders to retain or dispose of the Funds’ shares, other than the possible future termination of the Funds. The Funds may be terminated by reorganization into another mutual fund or by liquidation and distribution of their assets. Unless terminated by reorganization or liquidation, the Fund will continue indefinitely.

Liability

Under Massachusetts law, shareholders could, under certain circumstances, be held personally liable for the obligations of the Trust. However, the Trust’s Declaration of Trust disclaims any shareholder liability for acts or obligations of the Funds and the Trust and requires that notice of such disclaimer be given in each agreement, obligation, or instrument entered into or executed by a Fund or the Trustees. The Declaration of Trust provides for indemnification out of Fund property for all loss and expense of any shareholder held personally liable for the obligations of a Fund. Thus, the risk of a shareholder incurring financial loss on account of shareholder liability is limited to circumstances (which are considered remote) in which a Fund would be unable to meet its obligations and the disclaimer was inoperative. The risk of a Fund incurring financial loss on account of another series of the Trust also is believed to be remote, because it would be limited to circumstances in which the disclaimer was inoperative and the other series of the Trust was unable to meet its obligations.

Dividend Rights

The shareholders of a Fund are entitled to receive any dividends or other distributions declared for the Fund. No shares have priority or preference over any other shares of a Fund with respect to distributions. Distributions will be made from the assets of a Fund, and will be paid pro rata to all shareholders of the Fund (or class) according to the number of shares of the Fund (or class) held by shareholders on the record date. The amount of income dividends per share may vary between separate share classes of a Fund based upon differences in the way that expenses are allocated between share classes pursuant to a multiple class plan under Rule 18f-3 under the 1940 Act.

Voting Rights and Shareholder Meetings

As described in About the Trust, the Trust is not required to hold annual shareholder meetings, but special meetings may be called for certain purposes. Previously, the Trust had voluntarily undertaken to adhere to certain governance measures contemplated by a 2005 SEC settlement order with respect to the former affiliates of the Investment Manager. Over the past several years, the SEC has adopted many rules under the 1940 Act and the Investment Advisers Act of 1940 to strengthen fund governance and compliance oversight of mutual funds and their service providers. Accordingly, although the Trust may continue to follow certain governance practices noted in the 2005 settlement order, it will do so as the Board deems appropriate and not pursuant to any undertakings. The Board will convene meetings of shareholders to elect trustees as required by the 1940 Act or as deemed otherwise appropriate by the Board.

The Trustees may fill any vacancies on the Board except that the Trustees may not fill a vacancy if, immediately after filling such vacancy, fewer than two-thirds of the Trustees then in office would have been elected to such office by the shareholders. In addition, at such times as fewer than a majority of the Trustees then in office have been elected to such office by the shareholders, the Trustees must call a meeting of shareholders. Trustees may be removed from office by a vote of the holders of a majority of the outstanding shares at a meeting duly called for the purpose, or otherwise as specified in the Trust’s organizational documents. Except as otherwise disclosed in a Fund’s prospectuses and this SAI, the Trustees shall continue to hold office and may appoint their successors.

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At any shareholders’ meetings that may be held, shareholders of all series would vote together, irrespective of series, on the election of Trustees, but each series would vote separately from the others on other matters, such as changes in the investment policies of that series or the approval of the management agreement for that series. Shares of the Fund and any other series of the Trust that may be in existence from time to time generally vote together except when required by law to vote separately by Fund or by class.

Liquidation Rights

In the event of the liquidation or dissolution of the Trust or the Funds, shareholders of the Funds are entitled to receive the assets attributable to the relevant class of shares of the Funds that are available for distribution and to a distribution of any general assets not attributable to a particular investment portfolio that are available for distribution in such manner and on such basis as the Board may determine.

Preemptive Rights

There are no preemptive rights associated with Fund shares.

Conversion Rights

With the exception of Class B shares, which are closed to new investments by new and existing investors, shareholders have the right, which is subject to change by the Board, to convert or “exchange” shares of one class for another. Such right is outlined and subject to certain conditions set forth in each Fund’s prospectuses.

Redemptions

Each Fund’s dividend, distribution and redemption policies can be found in its prospectuses under the headings Buying, Selling and Exchanging Shares and Distributions and Taxes. The Trust may not suspend shareholders’ right of redemption or postpone payment for more than seven days unless the NYSE is closed for other than customary weekends or holidays, or if permitted by the rules of the SEC during periods when trading on the NYSE is restricted or during any emergency which makes it impracticable for the Funds to dispose of their securities or to determine fairly the value of its net assets, or during any other period permitted by order of the SEC for the protection of investors.

Sinking Fund Provisions

The Trust has no sinking fund provisions.

Calls or Assessment

All Fund shares are issued in uncertificated form only and when issued will be fully paid and non-assessable by the Trust.

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PURCHASE, REDEMPTION AND PRICING OF SHARES

Purchase and Redemption

An investor may buy, sell and exchange shares in the Funds utilizing the methods, and subject to the restrictions, described in the Funds’ prospectuses. The following information supplements the information in the Funds’ prospectuses.

The Funds have authorized one or more broker-dealers to accept buy and sell orders on the Funds’ behalf. These broker-dealers are authorized to designate other intermediaries to accept buy and sell orders on the Funds’ behalf. The Funds will be deemed to have received a buy or sell order when an authorized broker-dealer, or, if applicable, a broker-dealer’s authorized designee, accepts the order. Customer orders will be priced at each Fund’s net asset value (NAV) next computed after they are accepted by an authorized broker-dealer or the broker’s authorized designee.

The Trust also may honor redemption requests with in-kind distributions of readily marketable securities or other property if it is appropriate to do so in light of the Trust’s responsibilities under the 1940 Act.

Under the 1940 Act, the Funds may suspend the right of redemption or postpone the date of payment for shares during any period when (i) trading on the NYSE is restricted by applicable rules and regulations of the SEC; (ii) the NYSE is closed for other than customary weekend and holiday closings; (iii) the SEC has by order permitted such suspension; (iv) an emergency exists as determined by the SEC. (The Funds may also suspend or postpone the recordation of the transfer of their shares upon the occurrence of any of the foregoing conditions).

The Trust has elected to be governed by Rule 18f-1 under the 1940 Act, as a result of which each Fund is obligated to redeem shares, subject to the exceptions listed above, with respect to any one shareholder during any 90-day period, solely in cash up to the lesser of $250,000 or 1% of the NAV of each Fund at the beginning of the period.

The Trust does not have any arrangements with shareholders or other individuals that would permit frequent purchases or redemptions of Fund shares.

Redemption Fees (dollars in thousands)*

	Fiscal Year Ended December 31, 2010
	Columbia Acorn International	Columbia Acorn International Select
Redemption fees charged on redemptions retained by the Fund	$239,708	$10,223

* Prior to September 1, 2010, redemptions and or/exchanges of Class A, Class B, Class C and Class Z shares of Columbia Acorn International and Columbia Acorn International Select owned by a shareholder for 60 days or less were subject to a redemption fee 2.00% of the redemption proceeds.

The timing and magnitude of cash inflows from investors buying Fund shares could prevent a Fund from always being fully invested. Conversely, the timing and magnitude of cash outflows to investors redeeming Fund shares could require large ready reserves of uninvested cash to meet shareholder redemptions. Either situation could adversely impact a Fund’s performance.

Potential Adverse Effects of Large Investors

Each Fund may from time to time sell to one or more investors, including other funds advised by the Investment Manager or third parties, a substantial amount of its shares, and may thereafter be required to satisfy

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redemption requests by such investors. Such sales and redemptions may be very substantial relative to the size of the Fund. While it is not possible to predict the overall effect of such sales and redemptions over time, such transactions may adversely affect the Fund’s performance to the extent that the Fund is required to invest cash received in connection with a sale or to sell portfolio securities to facilitate a redemption at, in either case, a time when the Fund otherwise would not invest or sell. Such transactions also may increase a Fund’s transaction costs, which would detract from Fund performance. If a Fund is forced to sell portfolio securities that have appreciated in value, such sales may accelerate the realization of taxable income.

Privileges of Insurance Company Separate Accounts

Class A shares of a Fund may be sold to an insurance company separate account without the imposition of a front-end sales charge provided that the following conditions are met:

• The insurance company separate account is either (i) structured as a pool of IRA accounts managed by a sponsoring insurance company or (ii) for the benefit of group retirement plans;

• The sponsoring insurance company makes shares of the Fund available to its contract owners/investors without the imposition of a sales charge; and

• The sponsoring insurance company provides services to the investors in the insurance company separate account, including recordkeeping and administrative services, for which the sponsoring insurance company would be compensated by the Trust’s service providers and not by the Fund.

Additional Information about Investing in the Funds

Refer to the Fund’s prospectuses for details regarding how to buy, sell and exchange shares of the Funds.

The investment minimums for the Funds’ various share classes are set forth in the Funds’ prospectuses. Additional information about each of the Funds’ share classes and choosing among them is set forth in Appendix S.

Anti-Money Laundering Compliance

The Funds are required to comply with various anti-money laundering laws and regulations. Consequently, the Funds may request additional required information from you to verify your identity. Your application will be rejected if it does not contain your name, social security number, date of birth and permanent street address. If at any time the Funds believe a shareholder may be involved in suspicious activity or if certain account information matches information on government lists of suspicious persons, the Funds may choose not to establish a new account or may be required to “freeze” a shareholder’s account. The Funds also may be required to provide a governmental agency with information about transactions that have occurred in a shareholder’s account or to transfer monies received to establish a new account, transfer an existing account or transfer the proceeds of an existing account to a governmental agency. In some circumstances, the law may not permit the Funds to inform the shareholder that it has taken the actions described above.

Offering Price

Each Fund determines its NAV per share for each class, which is calculated separately for each class of shares as of the close of regular trading on the NYSE (generally 4:00 p.m. Eastern Time). NAV will not be determined on days when the NYSE is closed unless, in the judgment of the Board, the NAV of a Fund should be determined on any such day, in which case the determination will be made at 4:00 p.m. Eastern Time.

The value of each Fund’s portfolio securities is determined in accordance with the Trust’s Portfolio Pricing Policy, which is approved by the Board. As described under the heading Fair Valuation of Portfolio Securities

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below, Fund positions for which market quotations are not readily available are valued at a fair value as determined by the Valuation Committee of the Board in good faith under consistently applied procedures established by the Board. Principal valuation methodologies employed by the Funds are as follows:

Domestic Equity Securities; Portfolio Companies. To calculate the NAV on a given day, a Fund generally values each security in its portfolio for which a market quotation is readily available at the latest sale price quoted for the security that day on its principal exchange. If there are no sales that day, a Fund generally values the security at the mean of the latest bid and ask quotations. If a security is traded on NASDAQ, the security is priced using the SEC approved NASDAQ official closing price, or, if there are no sales, the security is priced at the mean of the closing bid and ask quotations. Equity securities that are not listed on any national exchange or NASDAQ are generally valued at the primary exchange closing mean price. Shares of open-end investment companies (other than ETFs but including the Portfolio Funds in which Columbia Thermostat Fund invests) are valued at the latest NAV reported by those companies. The Portfolio Funds generally value securities in their portfolios for which market quotations are readily available at the current market values of those securities (as determined by the policies of each Portfolio Fund) and all other securities and assets at fair value pursuant to methods established in good faith by the board of directors or trustees of each Portfolio Fund.

Foreign Equity Securities. Certain of the Funds and the Portfolio Funds may invest in securities which are primarily listed on foreign exchanges. Foreign securities are generally priced at the last sale price on the primary foreign exchange or may be priced using the closing price. However, because of differences in time zones between the United States and foreign securities markets, the prices of foreign securities may not fully reflect events that impact their current value. Generally, trading in foreign securities is substantially completed each day at various times prior to the time at which the Fund’s NAV is calculated and the values of the foreign securities used in determining the NAV are computed as of such different times. Foreign securities markets are sometimes open on days when U.S. markets are closed and the Fund’s NAV is not calculated. This means that the value of foreign securities owned by the Funds could change on days when Fund shares cannot be bought or sold. In addition, foreign securities markets may be closed on days when U.S. markets are open and the Fund’s NAV is calculated. This means that the NAV may be based on prices for the underlying foreign securities that are not current. If appropriate, the Valuation Committee of the Board may determine the fair value. In addition, the Funds utilize a statistical fair valuation process to adjust prices of the foreign securities under certain circumstances. See Fair Valuation of Portfolio Securities below.

Foreign Currencies; Forward Foreign Currency Contracts. The values of foreign securities quoted in foreign currencies are translated into U.S. dollars at the intraday spot rate provided by the data service set forth in the pricing procedures of the Investment Manager. Forward foreign currency contracts are valued in U.S. dollars based on the closing spot rate, adjusted by the forward points as of the time of pricing quoted by the data service specified in the pricing procedures of the Investment Manager.

Fair Valuation of Portfolio Securities

Rather than using the methods described above, the Valuation Committee of the Board will, pursuant to the Trust’s Portfolio Pricing Policy approved by the Board, determine in good faith a Fund portfolio security’s fair value in the event that price quotations or valuations are not readily available or reliable, in the judgment of the Investment Manager or the Valuation Committee, for example, when trading is halted or securities are not actively traded, such as restricted, illiquid and nonpublic securities. The fair value of a security is likely to be different from the quoted or published price and fair value determinations often require significant judgment.

The Valuation Committee determines the fair values of these securities utilizing the valuation methodology it deems most appropriate in the circumstances and considers all available, relevant factors and indications of value in reaching its decision. The Valuation Committee may consider, to the extent it deems a factor relevant, the following non-exhaustive list of factors in its fair value determination for a security: the value of other financial instruments, including derivative securities; trading volumes; values of baskets of securities; changes in

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interest rates; observations from financial institutions; government (domestic or foreign) actions or pronouncements; other news events; and, with respect to securities traded in foreign markets, the value of foreign securities traded in other foreign markets, ADR trading, closed-end fund trading, foreign currency exchange activity, and the trading prices of financial products that are tied to baskets of foreign securities.

In addition, foreign securities traded on foreign exchanges in time zones different from the United States are subject to fair value pricing in the event of a significant movement in Standard & Poor’s 500 Index (the “S&P 500”). In the event of such a movement the Investment Manager is required to obtain adjusted or “fair value” prices from a designated pricing vendor for each of the Funds’ foreign securities covered by the vendor. The fair value methodology applied by the vendor, in general, generates a factor applied to the closing price of the security on the foreign market that reflects that security’s expected price movement in response to the change in the S&P 500. When the Valuation Committee fair values a foreign security, it may also decide that the fair valuation adjustment factor supplied by the vendor should be applied, depending on the circumstances. Although the use of statistical fair valuation is intended to and may decrease opportunities for time zone arbitrage transactions, there can be no assurance that it will successfully decrease arbitrage opportunities.

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TAXATION

The following information supplements and should be read in conjunction with the section in the Funds’ prospectuses entitled Distributions and Taxes. The prospectuses generally describe the U.S. federal income tax treatment of distributions by the Funds. This section of the SAI provides additional information concerning U.S. federal income taxes. It is based on the Code, applicable U.S. Treasury Regulations, judicial authority, and administrative rulings and practice, all as in effect as of the printing of this SAI, and all of which are subject to change, including changes with retroactive effect. The following discussion does not address state, local or foreign tax matters.

A shareholder’s tax treatment may vary depending upon his or her particular situation. This discussion applies only to shareholders holding Fund shares as capital assets within the meaning of the Code. Except as otherwise noted, it may not apply to certain types of shareholders who may be subject to special rules, such as insurance companies, tax-exempt organizations, shareholders holding Fund shares through tax-advantaged accounts (such as 401(k) Plan Accounts, Individual Retirement Accounts, variable annuity contracts or variable life insurance contracts), financial institutions, broker-dealers, entities that are not organized under the laws of the United States or a political subdivision thereof, persons who are neither citizens nor residents of the United States, shareholders holding Fund shares as part of a hedge, straddle, or conversion transaction, and shareholders who are subject to the federal alternative minimum tax. Investors investing through variable annuity contracts and variable life insurance policies should be aware that an investment in the Fund is expected to be treated as one investment for purposes of the “adequate diversification” requirements of Code Section 817 and the Treasury Regulations thereunder. Such investors are encouraged to consult their tax advisors and financial planners as to the tax consequences of investing in the Fund, including any potential adverse impact on the favorable tax treatment of their variable contract or policy.

The Trust has not requested and will not request an advance ruling from the IRS as to the U.S. federal income tax matters described below. The IRS could adopt positions contrary to those discussed below and such positions could be sustained. In addition, the following discussion and the discussions in the prospectuses applicable to each shareholder address only some of the U.S. federal income tax considerations generally affecting investments in the Funds. Prospective shareholders are urged to consult with their own tax advisors and financial planners regarding the U.S. federal tax consequences of an investment in a Fund, the application of state, local, or foreign laws, and the effect of any possible changes in applicable tax laws on their investment in the Funds.

Qualification as a Regulated Investment Company

It is intended that each Fund qualify as a “regulated investment company” under Subchapter M of Subtitle A, Chapter 1 of the Code. Each Fund will be treated as a separate entity for U.S. federal income tax purposes. Thus, the provisions of the Code applicable to regulated investment companies generally will apply separately to each Fund, even though each Fund is a series of the Trust. Furthermore, each Fund will separately determine its income, gains, losses, and expenses for U.S. federal income tax purposes.

In order to qualify for the special tax treatment accorded regulated investment companies and their shareholders under the Code, each Fund must, among other things, derive at least 90% of its gross income each taxable year generally from (i) dividends, interest, certain payments with respect to securities loans, gains from the sale or other disposition of stock, securities or foreign currencies, and other income attributable to its business of investing in such stock, securities or foreign currencies (including, but not limited to, gains from options, futures or forward contracts) and (ii) net income derived from an interest in a qualified publicly traded partnership, as defined below. In general, for purposes of this 90% gross income requirement, income derived from a partnership will be treated as qualifying income only to the extent such income is attributable to items of income of the partnership which would be qualifying income if realized directly by the regulated investment company. However, 100% of the net income derived from an interest in a qualified publicly traded partnership

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(defined as a partnership that (a) the interests in which are traded on an established securities market or readily tradable on a secondary market or the substantial equivalent thereof, (b) that derives at least 90% of its income from the passive income sources defined in Code Section 7704(d), and (c) that derives less than 90% of its income from the qualifying income described in clause (i) above) will be treated as qualifying income. Certain of a Fund’s investments in master limited partnerships (MLPs) and ETFs, if any, may qualify as interests in qualified publicly traded partnerships. In addition, although in general the passive activity rules do not apply to a regulated investment company, such rules do apply to a regulated investment company with respect to items attributable to an interest in a qualified publicly traded partnership.

Each Fund must also diversify its holdings so that, at the end of each quarter of a Fund’s taxable year: (i) at least 50% of the fair market value of its total assets consists of (A) cash and cash items (including receivables), U.S. Government securities and securities of other regulated investment companies, and (B) securities of any one issuer (other than those described in clause (A)) to the extent such securities do not exceed 5% of the value of the Fund’s total assets and are not more than 10% of the outstanding voting securities of such issuer, and (ii) not more than 25% of the value of the Fund’s total assets consists of the securities of any one issuer (other than those described in clause (i)(A)), the securities of two or more issuers the Fund controls and which are engaged in the same, similar, or related trades or businesses, or the securities of one or more qualified publicly traded partnerships. In addition, for purposes of meeting this diversification requirement, the term “outstanding voting securities of such issuer” includes the equity securities of a qualified publicly traded partnership and in the case of a Fund’s investments in loan participations, the Fund shall treat both the financial intermediary and the issuer of the underlying loan as an issuer. The qualifying income and diversification requirements described above may limit the extent to which a Fund can engage in certain derivative transactions, including, but not limited to, options, futures contracts, swap agreements and commodity-linked instruments, as well as the extent to which it can invest in MLPs and certain commodity-linked ETFs.

In addition, each Fund generally must distribute to its shareholders at least 90% of its investment company taxable income for the taxable year, which generally includes its ordinary income and the excess of any net short-term capital gain over net long-term capital loss, and at least 90% of its net tax-exempt interest income (if any) for the taxable year.

If a Fund qualifies as a regulated investment company, it generally will not be subject to U.S. federal income tax on any of the investment company taxable income and net capital gain (i.e., the excess of net long-term capital gain over net short-term capital loss) it distributes to its shareholders (including Capital Gains Dividends, as defined below). Each Fund generally intends to distribute at least annually its investment company taxable income (computed without regard to the dividends-paid deduction) and substantially all of its capital gain. However, no assurance can be given that a Fund will not be subject to U.S. federal income taxation. Any investment company taxable income retained by a Fund will be subject to tax at regular corporate rates.

In addition, although each Fund generally intends to distribute all of its net capital gain, a Fund may determine to retain for investment all or a portion of its net capital gain. If a Fund retains any net capital gain, it will be subject to a tax at regular corporate rates on the amount retained, but may designate the retained amount as undistributed capital gains in a notice to its shareholders, who (i) will be required to include in income for U.S. federal income tax purposes, as long-term capital gain, their shares of such undistributed amount, and (ii) will be entitled to credit their proportionate shares of the tax paid by the Fund on such undistributed amount against their U.S. federal income tax liabilities, if any, and to claim refunds to the extent the credit exceeds such liabilities. For U.S. federal income tax purposes, the tax basis of shares owned by a shareholder of a Fund will be increased by an amount equal under current law to the difference between the amount of undistributed capital gains included in the shareholder’s gross income under clause (i) of the preceding sentence and the tax deemed paid by the shareholder under clause (ii) of the preceding sentence.

In determining its net capital gain for Capital Gain Dividend purposes, a regulated investment company generally must treat any net capital loss or any net long-term capital loss incurred after October 31 of a given

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year as if it had been incurred in the succeeding year. U.S. Treasury Regulations permit a regulated investment company, in determining its taxable income, to elect to treat all or part of any net capital loss, any net long-term capital loss or any foreign currency loss incurred after October 31 as if it had been incurred in the succeeding year.

In order to comply with the distribution requirements described above applicable to regulated investment companies, a Fund generally must make the distributions in the same taxable year in which it realizes the income and gain, although in certain circumstances, a Fund may make the distributions in the following taxable year in respect of income and gains from the prior taxable year. If a Fund declares a distribution to shareholders of record in October, November or December of one calendar year and pays the distribution by January 31 of the following calendar year, however, the Fund and its shareholders will be treated as if the Fund paid the distribution by December 31 of the earlier year.

If, for any taxable year, a Fund fails to qualify as a regulated investment company under the Code, it will be taxed in the same manner as an ordinary corporation without any deduction for its distributions to shareholders, and all distributions from the Fund’s current and accumulated earnings and profits (including any distributions of its net tax-exempt income and net long-term capital gains) to its shareholders will be taxable to shareholders as dividend income. In addition, the Fund could be required to recognize unrealized gains, pay substantial taxes and interest and make substantial distributions before requalifying as a regulated investment company.

Excise Tax

If a Fund fails to distribute by December 31 of each calendar year at least the sum of 98% of its ordinary income for that year (excluding capital gains and losses) and 98.2% of its capital gain net income (adjusted for net ordinary losses) for the one-year period ending on October 31 of that year (or November 30 or December 31 of that year if the Fund is permitted to elect and so elects), and any of its ordinary income and capital gain net income from previous years that were not distributed during such years, the Fund will be subject to a nondeductible 4% excise tax on the undistributed amounts. For these purposes, ordinary gains and losses from the sale, exchange, or other taxable disposition of property that would be properly taken into account after October 31 of a calendar year (or November 30 if the Fund is permitted to elect and so elects) are generally treated as arising on January 1 of the following calendar year. For purposes of the excise tax, a Fund will be treated as having distributed any amount on which it has been subject to corporate income tax in the taxable year ending within the calendar year. Each Fund generally intends to actually distribute or be deemed to have distributed substantially all of its ordinary income and capital gain net income, if any, by the end of each calendar year and, thus, expects not to be subject to the excise tax. However, no assurance can be given that a Fund will not be subject to the excise tax. Moreover, each Fund reserves the right to pay an excise tax rather than make an additional distribution when circumstances warrant (for example, if the amount of excise tax to be paid is deemed de minimis by a Fund).

Capital Loss Carryforwards

Capital losses in excess of capital gains (“net capital losses”) are not permitted to be deducted against a Fund’s net investment income. Instead, subject to certain limitations, a Fund is able to carry forward a net capital loss from any taxable year to offset its capital gains, if any, realized during a subsequent taxable year. If a Fund incurs or has incurred net capital losses in taxable years beginning after December 22, 2010 (“post-2010 losses”), those losses will be carried forward to one or more subsequent taxable years without expiration; any such carryforward losses will retain their character as short-term or long-term. If a Fund incurred net capital losses in a taxable year beginning on or before December 22, 2010 (“pre-2011 losses”), the Fund is permitted to carry such losses forward for eight taxable years; in the year to which they are carried forward, such losses are treated as short-term capital losses that first offset short-term capital gains, and then offset any long-term capital gains. The Fund must use any post 2010-losses, which will not expire, before it uses any pre-2011 losses. This increases the likelihood that pre-2011 losses will expire unused at the conclusion of the

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eight-year carryforward period. Capital gains that are offset by carried forward capital losses are not subject to fund-level U.S. federal income taxation, regardless of whether they are distributed to shareholders. Accordingly, the Funds do not expect to distribute any such offsetting capital gains. The Funds cannot carry back or carry forward any net operating losses.

Taxation of Fund Investments

In general, realized gains or losses on the sale of securities held by a Fund will be treated as capital gains or losses, and long-term capital gains or losses if the Fund has held or is deemed to have held the securities for more than one year at the time of disposition.

If a Fund purchases a debt obligation with original issue discount (OID) (generally a debt obligation with an issue purchase price less than its stated principal amount, such as a zero-coupon bond), the Fund may be required to annually include in its income a portion of the OID as ordinary income, even though the Fund will not receive cash payments for such discount until maturity or disposition of the obligation. Inflation-protected bonds generally can be expected to produce OID income as their principal amounts are adjusted upward for inflation. In general, gains recognized on the disposition of (or the receipt of any partial payment of principal on) a debt obligation (including a municipal obligation) purchased by a Fund at a market discount, generally at a price less than its principal amount, will be treated as ordinary income to the extent of the portion of market discount which accrued, but was not previously recognized pursuant to an available election, during the term that the Fund held the debt obligation. A Fund generally will be required to make distributions to shareholders representing the OID or market discount (if an election is made by the Fund to accrue market discount over the holding period of the applicable debt obligation) on debt securities that is currently includible in income, even though the cash representing such income may not have been received by the Fund. Cash to pay such distributions may be obtained from borrowing or from sales proceeds of securities held by a Fund which the Fund otherwise might have continued to hold; obtaining such cash might be disadvantageous for the Fund. In addition, payment-in-kind securities similarly will give rise to income which is required to be distributed and is taxable even though a Fund receives no cash interest payment on the security during the year.

If a Fund invests in debt obligations that are in the lowest rating categories or are unrated, including debt obligations of issuers not currently paying interest or who are in default, special tax issues may exist for the Fund. Tax rules are not entirely clear about issues, such as whether a Fund should recognize market discount on a debt obligation and, if so, the amount of market discount the Fund should recognize, when a Fund may cease to accrue interest, OID or market discount, when and to what extent deductions may be taken for bad debts or worthless securities and how payments received on obligations in default should be allocated between principal and income. These and other related issues will be addressed by a Fund when, as and if it invests in such securities, in order to seek to ensure that it distributes sufficient income to preserve its status as a regulated investment company and does not become subject to U.S. federal income or excise tax.

Foreign exchange gains and losses realized by a Fund in connection with certain transactions involving foreign currency-denominated debt securities, certain options, futures contracts, forward contracts and similar instruments relating to foreign currency, foreign currencies, or payables or receivables denominated in a foreign currency are subject to Section 988 of the Code, which generally causes such gains and losses to be treated as ordinary income or loss and may affect the amount and timing of recognition of the Fund’s income. Under future U.S. Treasury Regulations, any such transactions that are not directly related to a Fund’s investments in stock or securities (or its options contracts or futures contracts with respect to stock or securities) may have to be limited in order to enable the Fund to satisfy the 90% qualifying income test described above. If the net foreign exchange loss exceeds a Fund’s net investment company taxable income (computed without regard to such loss) for a taxable year, the resulting ordinary loss for such year will not be available as a carryforward and thus cannot be deducted by the Fund or its shareholders in future years.

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If the Fund makes a distribution of income received by the Fund in lieu of dividends (a “substitute payment”) with respect to securities on loan pursuant to a securities lending transaction, that income will not constitute qualified dividend income to individual shareholders and will not be eligible for the dividends-received deduction for corporate shareholders. Similar consequences may apply to repurchase and other derivative transactions. Similarly, to the extent that a Fund makes distributions of income received by the Fund in lieu of tax-exempt interest with respect to securities on loan, such distributions will not constitute exempt-interest dividends (defined below) to shareholders.

A Fund’s transactions in securities and certain types of derivatives (e.g., options, futures contracts, forward contracts and swap agreements), as well as any of its hedging, short sale, securities loan or similar transactions, may be subject to special tax rules, such as the notional principal contract, straddle, constructive sale, wash-sale or short-sale rules, the effect of which may be to accelerate income to the Fund, defer losses to the Fund, cause adjustments in the holding periods of the Fund’s securities, convert long-term capital gains into short-term capital gains, and/or convert short-term capital losses into long-term capital losses. Rules governing U.S. federal income tax aspects of such transactions and derivatives, including with respect to certain commodity-linked investments, are in a developing stage and are not entirely clear in certain respects. Accordingly, while each Fund intends to account for such transactions in a manner it deems to be appropriate, an adverse determination or future guidance by the IRS with respect to these rules (which determination or guidance could be retroactive) may affect whether a Fund has made sufficient distributions, and otherwise satisfied the relevant requirements to maintain its qualification as a regulated investment company and avoid fund-level tax. Certain requirements that must be met under the Code in order for a Fund to qualify as a regulated investment company may limit the extent to which a Fund will be able to engage in certain derivatives or commodity-linked transactions.

Certain of a Fund’s hedging activities (including its transactions, if any, in foreign currencies or foreign currency-denominated instruments) are likely to produce a difference between its book income and its taxable income. If a Fund’s book income exceeds the sum of its taxable income and net tax-exempt income (if any), the distribution (if any) of such excess generally will be treated as (i) a dividend to the extent of the Fund’s remaining earnings and profits (including earnings and profits arising from tax exempt income), (ii) thereafter, as a return of capital to the extent of the recipient’s basis in its shares, and (iii) thereafter, as gain from the sale or exchange of a capital asset. If a Fund’s book income is less than the sum of its taxable income, and net tax-exempt income, (if any), the Fund could be required to make distributions exceeding book income to qualify as a regulated investment company.

Amounts realized by a Fund from sources within foreign countries (e.g., dividends or interest paid on foreign securities) may be subject to withholding and other taxes imposed by such countries; such taxes would reduce the Fund’s return on those investments. Tax conventions between certain countries and the United States may reduce or eliminate such taxes.

A Fund may invest directly or indirectly in residual interests in REMICs or equity interests in taxable mortgage pools (TMPs). Under an IRS notice, and U.S. Treasury Regulations that have yet to be issued but may apply retroactively, a portion of a Fund’s income (including income allocated to the Fund from a pass-through entity) that is attributable to a residual interest in a REMIC or an equity interest in a TMP (referred to in the Code as an “excess inclusion”) will be subject to U.S. federal income tax in all events. This notice also provides, and the regulations are expected to provide, that excess inclusion income of a regulated investment company, such as a Fund, will be allocated to shareholders of the regulated investment company in proportion to the dividends received by such shareholders, with the same consequences as if the shareholders held the related interest directly. As a result, the Fund may not be a suitable investment for certain tax-exempt shareholders, as noted under Tax-Exempt Shareholders below.

In general, excess inclusion income allocated to shareholders (i) cannot be offset by net operating losses (subject to a limited exception for certain thrift institutions), (ii) will constitute unrelated business taxable income

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(UBTI) to entities (including a qualified pension plan, an individual retirement account, a 401(k) plan, a Keogh plan or certain other tax-exempt entities) subject to tax on UBTI, thereby potentially requiring such an entity that is allocated excess inclusion income, and otherwise might not be required to file a tax return, to file a tax return and pay tax on such income, and (iii) in the case of a foreign shareholder, will not qualify for any reduction in U.S. federal withholding tax.

Income of a Fund that would be UBTI if earned directly by a tax-exempt entity will not generally be attributed as UBTI to a tax-exempt shareholder of the Fund. Notwithstanding this “blocking” effect, a tax-exempt shareholder could realize UBTI by virtue of its investment in the Fund if shares in the Fund constitute debt-financed property in the hands of the tax-exempt shareholder within the meaning of Code Section 514(b).

Some amounts received by a Fund from its investments in MLPs will likely be treated as returns of capital because of accelerated deductions available with respect to the activities of MLPs. On the disposition of an investment in such an MLP, the Fund will likely realize taxable income in excess of economic gain from that asset (or if, in later periods, a Fund does not dispose of the MLP, the Fund will likely realize taxable income in excess of cash flow received by the Fund from the MLP), and the Fund must take such income into account in determining whether the Fund has satisfied its regulated investment company distribution requirements. The Fund may have to borrow or liquidate securities to satisfy its distribution requirements and meet its redemption requests, even though investment considerations might otherwise make it undesirable for the Fund to borrow money or sell securities at the time. In addition, distributions attributable to gain from the sale of MLPs could be characterized as ordinary income under the Code’s recapture provisions.

As noted above, certain of the ETFs and MLPs in which a Fund may invest qualify as qualified publicly traded partnerships. In such cases, the net income derived from such investments will constitute qualifying income for purposes of the 90% gross income requirement described earlier for qualification as a regulated investment company. If, however, such a vehicle were to fail to qualify as a qualified publicly traded partnership in a particular year, all or a portion of the gross income derived from it in such year could constitute nonqualifying income to a Fund for purposes of the 90% gross income requirement and thus could adversely affect the Fund’s ability to qualify as a regulated investment company for a particular year. In addition, as described above, the diversification requirement for regulated investment company qualification will limit a Fund’s investments in one or more vehicles that are qualified publicly traded partnerships to 25% of the Fund’s total assets as of the end of each quarter of the Fund’s taxable year.

“Passive foreign investment companies” (PFICs) are generally defined as foreign corporations where at least 75% of their gross income for their taxable year is income from passive sources (such as interest, dividends, certain rents and royalties, or capital gains) or at least 50% of their assets on average produce such passive income or are held to produce such passive income. If a Fund acquires any equity interest in a PFIC, the Fund could be subject to U.S. federal income tax and interest charges on “excess distributions” received from the PFIC or on gain from the sale of such equity interest in the PFIC, even if all income or gain actually received by the Fund is timely distributed to its shareholders.

Elections may be available that would ameliorate these adverse tax consequences, but such elections would require a Fund to include its share of the PFIC’s income and net capital gains annually, regardless of whether it receives any distribution from the PFIC (in the case of a “QEF election”), or to mark the gains (and to a limited extent losses) in its interests in the PFIC “to the market” as though the Fund had sold and repurchased such interests on the last day of the Fund’s taxable year, treating such gains and losses as ordinary income and loss (in the case of a “mark-to-market election”). The QEF and mark-to-market elections may require a Fund to recognize taxable income or gain without the concurrent receipt of cash and increase the amount required to be distributed by the Fund to avoid taxation. Making either of these elections therefore may require a Fund to liquidate other investments prematurely to meet the minimum distribution requirements described above, which also may adversely affect the Fund’s total return. Each Fund may attempt to limit and/or manage its holdings in PFICs to minimize tax liability and/or maximize returns from these investments but there can be no assurance

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that it will be able to do so. Moreover, because it is not always possible to identify a foreign corporation as a PFIC in advance of acquiring shares in the corporation, a Fund may incur the tax and interest charges described above in some instances. Dividends paid by PFICs will not be eligible to be treated as qualified dividend income, as defined below.

In addition to the investments described above, prospective shareholders should be aware that other investments made by a Fund may involve complex tax rules that may result in income or gain recognition by the Fund without corresponding current cash receipts. Although each Fund seeks to avoid significant noncash income, such noncash income could be recognized by a Fund, in which case the Fund may distribute cash derived from other sources in order to meet the minimum distribution requirements described above. In this regard, a Fund could be required at times to liquidate investments prematurely in order to satisfy its minimum distribution requirements, which may accelerate the recognition of gain and adversely affect the Fund’s total return.

Taxation of Distributions

Except for exempt-interest dividends (defined below) paid by a Fund, distributions paid out of a Fund’s current and accumulated earnings and profits, whether paid in cash or reinvested in the Fund, generally are deemed to be taxable distributions and must be reported by each shareholder who is required to file a U.S. federal income tax return. Dividends and distributions on a Fund’s shares are generally subject to U.S. federal income tax as described herein to the extent they do not exceed the Fund’s realized income and gains, even though such dividends and distributions may economically represent a return of a particular shareholder’s investment. Such distributions are likely to occur in respect of shares purchased at a time when the Fund’s net asset value (NAV) reflects either unrealized gains or realized but undistributed income or gains. Such realized income and gains may be required to be distributed even when the Fund’s NAV also reflects unrealized losses. For U.S. federal income tax purposes, a Fund’s earnings and profits, described above, are determined at the end of the Fund’s taxable year and are allocated pro rata to distributions paid over the entire year. Distributions in excess of a Fund’s current and accumulated earnings and profits will first be treated as a return of capital up to the amount of a shareholder’s tax basis in his or her Fund shares and then as capital gain. A return of capital is not taxable, but it reduces a shareholder’s tax basis in his or her Fund shares, thus reducing any loss or increasing any gain on a subsequent taxable disposition by the shareholder of his or her shares. A Fund may make distributions in excess of its earnings and profits to a limited extent, from time to time.

For U.S. federal income tax purposes, distributions of investment income (except for exempt-interest dividends and qualified dividend income, each defined below) are generally taxable as ordinary income, and distributions of gains from the sale of investments that a Fund owned (or is deemed to have owned) for one year or less will be taxable as short-term capital gains (which bear the same rate as ordinary income). Distributions properly designated by a Fund as capital gain dividends (Capital Gains Dividends) will be taxable to shareholders as long-term capital gain (to the extent such distributions do not exceed the Fund’s actual net long-term capital gain for the taxable year), regardless of how long a shareholder has held Fund shares, and do not qualify as dividends for purposes of the dividends-received deduction or as qualified dividend income (defined below). Each Fund will designate Capital Gain Dividends, if any, in a written notice mailed by the Fund to its shareholders not later than 60 days after the close of the Fund’s taxable year.

“Exempt-interest dividends” are dividends (other than capital gain dividends) paid by a RIC that are properly reported as such in a written statement furnished to shareholders and attributable to tax-exempt interest earned by the Fund. For taxable years beginning after December 22, 2010, if the Fund is a “qualified fund of funds,” the Fund can elect to allow its shareholders the benefit of exempt-interest dividends without regard to the requirement that more than 50% of the value of its total assets consist of bonds which pay tax-exempt interest. The Fund will qualify as a “qualified fund of funds” if at least 50% of the Fund’s value of the

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total assets of which (at the close of each quarter of the taxable year) is represented by interests in other regulated investment companies.

Some states will not tax distributions made to individual shareholders that are attributable to interest a Fund earns on direct obligations of the U.S. Government if the Fund meets the state’s minimum investment or reporting requirements, if any. Investments in GNMA or FNMA securities, bankers’ acceptances, commercial paper, and repurchase agreements collateralized by U.S. Government securities generally do not qualify for tax-free treatment. This exemption may not apply to corporate shareholders.

Sales and Exchanges of Fund Shares

If a shareholder sells or exchanges his or her Fund shares, he or she generally will realize a taxable capital gain or loss on the difference between the amount received for the shares (or deemed received in the case of an exchange) and his or her tax basis in the shares. This gain or loss will be long-term capital gain or loss if he or she has held (or is deemed to have owned) such Fund shares for more than one year at the time of the sale or exchange, and short-term capital gain or loss otherwise.

If a shareholder sells or exchanges Fund shares within 90 days of having acquired such shares and if, as a result of having initially acquired those shares, he or she subsequently pays a reduced sales charge on a new purchase of shares of the Fund or a different regulated investment company, the sales charge previously incurred in acquiring the Fund’s shares generally shall not be taken into account (to the extent the previous sales charges do not exceed the reduction in sales charges on the new purchase) for the purpose of determining the amount of gain or loss on the disposition, but generally will be treated as having been incurred in the new purchase. This sales charge basis deferral rule shall apply only when a shareholder makes such new acquisition of Fund shares or shares of a different regulated investment company during the period beginning on the date the original Fund shares are disposed of and ending on January 31 of the calendar year following the calendar year the original Fund shares are disposed of. Also, if a shareholder realizes a loss on a disposition of Fund shares, the loss will be disallowed under “wash sale” rules to the extent that he or she purchases substantially identical shares within the 61-day period beginning 30 days before and ending 30 days after the disposition. Any disallowed loss generally will be reflected in an adjustment to the tax basis of the purchased shares.

If a shareholder receives a Capital Gain Dividend or is deemed to receive a distribution of long-term capital gain with respect to any Fund share and such Fund share is held or treated as held for six months or less, then (unless otherwise disallowed) any loss on the sale or exchange of that Fund share will be treated as a long-term capital loss to the extent of the Capital Gain Dividend or distribution of long-term capital gain. If shares of a Fund are sold at a loss after being held for six months or less, the loss will be disallowed to the extent of any exempt-interest dividends received on those shares.

Foreign Taxes

Amounts realized by a Fund from sources within foreign countries may be subject to withholding and other taxes imposed by such countries. Tax conventions between certain countries and the United States may reduce or eliminate such taxes. If more than 50% of the value of a Fund’s total assets at the close of its taxable year consists of securities of foreign corporations, the Fund will be eligible to file an annual election with the IRS pursuant to which the Fund may pass-through to its shareholders on a pro rata basis foreign income and similar taxes paid by the Fund with respect to foreign securities that the Fund has held for at least the minimum holding periods specified in the Code and such taxes may be claimed, subject to certain limitations, either as a tax credit or deduction by the shareholders.

For taxable years beginning after December 22, 2010, if the Fund is a “qualified fund of funds,” the Fund can elect to allow its shareholders the foreign tax credit without regard to the requirement that more than 50% of the value of its total assets consist of stock or securities in foreign corporations. The Fund will qualify as a

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“qualified fund of funds” if at least 50% of the Fund’s value of the total assets of which (at the close of each quarter of the taxable year) is represented by interests in other regulated investment companies.

U.S. Federal Income Tax Rates

As of the date of this SAI, the maximum stated U.S. federal income tax rate applicable to individuals generally is 35% for ordinary income and 15% for net long-term capital gain. Long-term capital gain rates applicable to individuals have been reduced — in general, to 15% with a 0% rate applying to taxpayers in the 10% and 15% rate brackets — for taxable years beginning before January 1, 2013.

Current U.S. federal income tax law also provides for a maximum individual U.S. federal income tax rate applicable to “qualified dividend income” equal to the highest net long-term capital gain rate, which generally is 15%. It is currently unclear whether Congress will extend the reduction in capital gain rates or this qualified dividend income provision to or for tax years beginning on or after January 1, 2013. In general, “qualified dividend income” is income attributable to dividends received by a Fund in taxable years beginning on or before December 31, 2012 from certain domestic and foreign corporations, as long as certain holding period and other requirements are met by the Fund with respect to the dividend-paying corporation’s stock and by the shareholders with respect to the Fund’s shares. If 95% or more of a Fund’s gross income (excluding net long-term capital gain over net short-term capital loss) constitutes qualified dividend income, all of its distributions (other than Capital Gain Dividends) will be generally treated as qualified dividend income in the hands of individual shareholders, as long as they have owned their Fund shares for at least 61 days during the 121-day period beginning 60 days before the Fund’s ex-dividend date (or, in the case of certain preferred stock, 91 days during the 181-day period beginning 90 days before such date) and meet certain other requirements specified in the Code. In general, if less than 95% of a Fund’s income is attributable to qualified dividend income, then only the portion of the Fund’s distributions that is attributable to qualified dividend income and designated as such in a timely manner will be so treated in the hands of individual shareholders who meet the aforementioned requirements. The rules regarding the qualification of Fund distributions as qualified dividend income are complex, including the holding period requirements. Individual Fund shareholders therefore are urged to consult their own tax advisors and financial planners.

The maximum stated corporate U.S. federal income tax rate applicable to ordinary income and net capital gain is 35%. Actual marginal tax rates may be higher for some shareholders, for example, through reductions in deductions. Naturally, the amount of tax payable by any taxpayer will be affected by a combination of tax laws covering, for example, deductions, credits, deferrals, exemptions, sources of income and other matters. U.S. federal income tax rates are set to increase in future years under various “sunset” provisions of U.S. federal income tax laws. In particular, for taxable years beginning after December 31, 2012, the maximum capital gain rate applicable to long-term capital gains of individuals is scheduled to increase to 20% and the favorable treatment of qualified dividend income is scheduled to expire.

For taxable years beginning on or after January 1, 2013, Section 1411 of the Code generally imposes a 3.8% Medicare contribution tax on certain high-income individuals, trusts and estates. For individuals, the 3.8% tax will apply to the lesser of (1) the amount (if any) by which the taxpayer’s modified adjusted gross income exceeds certain threshold amounts or (2) the taxpayer’s “net investment income.” For this purpose, “net investment income” generally includes, among other things, (i) distributions paid by a Fund of net investment income and capital gains (other than exempt-interest dividends) as described above, and (ii) any net gain recognized on the sale, redemption, exchange or other taxable disposition of Fund shares. The details of the implementation of this tax and of the calculation of net investment income, among other issues, are currently unclear and remain subject to future guidance. Shareholders are advised to consult their tax advisors regarding the possible implications of this additional tax on their investment in a Fund.

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Backup Withholding

Each Fund generally is required to withhold, and remit to the U.S. Treasury, subject to certain exemptions, an amount equal to 28% of all distributions and redemption proceeds (including proceeds from exchanges and redemptions in-kind) paid or credited to a Fund shareholder if (1) the shareholder fails to furnish the Fund with a correct “taxpayer identification number” (TIN) or has not certified to the Fund that withholding does not apply or (2) the IRS notifies the Fund that the shareholder’s TIN is incorrect or the shareholder is otherwise subject to backup withholding. These backup withholding rules may also apply to distributions that are properly designated as exempt-interest dividends. This backup withholding is not an additional tax imposed on the shareholder. The shareholder may apply amounts required to be withheld as a credit against his or her future U.S. federal income tax liability, provided that the required information is furnished to the IRS. If a shareholder fails to furnish a valid TIN upon request, the shareholder can also be subject to IRS penalties. The rate of backup withholding is set to increase for amounts distributed or paid after December 31, 2012.

Tax-Deferred Plans

The shares of a Fund may be available for a variety of tax-deferred retirement and other tax-advantaged plans and accounts. Prospective investors should contact their tax advisors and financial planners regarding the tax consequences to them of holding Fund shares through such plans and/or accounts.

Corporate Shareholders

Subject to limitations and other rules, a corporate shareholder of a Fund may be eligible for the dividends-received deduction on Fund distributions attributable to dividends received by the Fund from domestic corporations, which, if received directly by the corporate shareholder would qualify for such a deduction. For eligible corporate shareholders, the dividends-received deduction may be subject to certain reductions, and a distribution by a Fund attributable to dividends of a domestic corporation will be eligible for the deduction only if certain holding period and other requirements are met. These requirements are complex; therefore, corporate shareholders of the Funds are urged to consult their own tax advisors and financial planners.

As discussed above, a portion of the interest paid or accrued on certain high-yield discount obligations that a Fund may own may not be deductible to the issuer. If a portion of the interest paid or accrued on these obligations is not deductible, that portion will be treated as a dividend. In such cases, if the issuer of the obligation is a domestic corporation, dividend payments by a Fund may be eligible for the dividends-received deduction to the extent of the dividend portion of such interest.

Foreign Shareholders

For purposes of this discussion, “foreign shareholders” generally include: (i) nonresident alien individuals, (ii) foreign trusts (i.e., a trust other than a trust with respect to which a U.S. court is able to exercise primary supervision over administration of that trust and one or more U.S. persons have authority to control substantial decisions of that trust), (iii) foreign estates (i.e., the income of which is not subject to U.S. tax regardless of source) and (iv) foreign corporations.

Generally, unless an exception applies, distributions made to foreign shareholders other than Capital Gain Dividends and exempt-interest dividends will be subject to non-refundable U.S. federal income tax withholding at a 30% rate (or such lower rate as may be provided under an applicable income tax treaty) even if they are funded by income or gains (such as portfolio interest, short-term capital gains, or foreign-source dividend and interest income) that, if paid to a foreign person directly, would not be subject to withholding. However, generally, for taxable years beginning before January 1, 2012, distributions made to foreign shareholders and properly designated by a Fund as “interest-related dividends” were exempt from U.S. federal income tax

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withholding. The exemption for interest-related dividends did not apply to any distribution to a foreign shareholder (i) to the extent that the dividend was attributable to certain interest on an obligation if the foreign shareholder was the issuer or was a 10% shareholder of the issuer, (ii) that was within certain foreign countries that had inadequate information exchange with the United States or (iii) to the extent the dividend was attributable to interest paid by a person that was a related person of the foreign shareholder and the foreign shareholder was a controlled foreign corporation. Interest-related dividends are generally attributable to the Fund’s net U.S.-source interest income of types similar to those not subject to U.S. federal income tax if earned directly by an individual foreign shareholder. In order for a distribution to qualify as an interest-related dividend, the Fund was required to report it as such such in a written notice furnished to its shareholders. Notwithstanding the foregoing, if a distribution described above is “effectively connected” with a U.S. trade or business (or, if an income tax treaty applies, is attributable to a U.S. permanent establishment) of the recipient foreign shareholder, neither U.S. federal income tax withholding nor the exemption for interest-related dividends (if otherwise applicable) will apply. Instead, the distribution will be subject to the tax, reporting and withholding requirements generally applicable to U.S. persons, and an additional branch profits tax may apply if the recipient foreign shareholder is a foreign corporation.

In general, a foreign shareholder’s capital gains realized on the disposition of Fund shares and distributions properly designated as Capital Gain Dividends are not subject to U.S. federal income or withholding tax unless: (i) such gains or distributions are effectively connected with a U.S. trade or business (or, if an income tax treaty applies, are attributable to a U.S. permanent establishment) of the foreign shareholder; or (ii) in the case of an individual foreign shareholder, the shareholder is present in the U.S. for a period or periods aggregating 183 days or more during the year of the disposition of Fund shares or the receipt of Capital Gain Dividends and certain other conditions are met. If the requirements of clause (i) are met, the tax, reporting and withholding requirements applicable to U.S. persons generally will apply to the foreign shareholder, and an additional branch profits tax may apply if the foreign shareholder is a foreign corporation. If the requirements of clause (i) are not met, but the requirements of clause (ii) are met, such gains and distributions will be subject to U.S. federal income tax at a 30% rate (or such lower rate provided under an applicable income tax treaty). With respect to taxable years of a Fund beginning before January 1, 2012, distributions to a foreign shareholder attributable to the Fund’s net short-term capital gain in excess of its net long-term capital loss and reported as such by the Fund in a written notice, furnished to its shareholders (“short-term capital gain dividends”) were generally not subject to U.S. federal income or withholding tax unless clause (i), (ii) or (iii) above applies to such distributions.

It is currently unclear whether Congress will extend the exemptions from withholding for interest-related dividends and short-term capital gain dividends with respect to taxable years of a Fund beginning on or after January 1, 2012 and what the terms of any such extension would be, including whether any such extension would have retroactive effect. Even if permitted to do so, each Fund provides no assurance that it would report any distributions as interest-related dividends or short-term capital gain dividends.

In the case of shares held through an intermediary, even if a Fund makes a designation with respect to a payment, no assurance can be made that the intermediary will respect such a designation, and an intermediary may withhold even if a Fund makes a designation with respect to a payment. Foreign shareholders should contact their intermediaries regarding the application of these rules to their accounts.

Even if permitted to do so, each Fund provides no assurance that it will designate any distributions as interest-related dividends or short-term capital gain dividends.

Special rules apply to certain distributions to certain foreign shareholders from a regulated investment company that is either a “U.S. real property holding corporation” (USRPHC) or would be a USRPHC absent exclusions from the definition thereof for interests in domestically controlled REITs (or, prior to January 1, 2012, regulated investment companies) and not-greater-than-5% interests in publicly traded classes of stock in REITs or regulated investment companies. Additionally, special rules apply to the sale of shares in a regulated

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investment company that is a USRPHC. Generally, a USRPHC is a domestic corporation that holds U.S. real property interests (USRPIs) — USRPIs are defined very generally as any interest in U.S. real property or any equity interest in a USRPHC — the fair market value of which equals or exceeds 50% of the sum of the fair market values of the corporation’s USRPIs, interests in real property located outside the United States and other assets. The Funds generally do not expect that they will be USRPHCs or would be USRPHCs but for the above-mentioned exceptions and thus do not expect that these special tax rules will apply.

In order to qualify for any exemptions from withholding described above or for lower withholding tax rates under income tax treaties, or to establish an exemption from backup withholding, a foreign shareholder must comply with applicable certification requirements relating to its foreign status (including, in general, furnishing an IRS Form W-8BEN or substitute form). Foreign shareholders should consult their tax advisers in this regard.

Special rules (including withholding and reporting requirements) apply to foreign partnerships and those holding Fund shares through foreign partnerships. In addition, additional considerations may apply to foreign trusts and foreign estates. Investors holding Fund shares through foreign entities should consult their tax advisors about their particular situation.

A beneficial holder of shares who is a foreign person may be subject to state and local tax and to the U.S. federal estate tax in addition to the U.S. federal income tax referred to above.

Tax-Exempt Shareholders

Under current law, a Fund generally serves to “block” (that is, prevent the attribution to shareholders of) UBTI from being realized by tax-exempt shareholders. Notwithstanding this “blocking” effect, a tax-exempt shareholder could realize UBTI by virtue of its investment in a Fund if shares in the Fund constitute debt-financed property in the hands of the tax-exempt shareholder within the meaning of Code Section 514(b).

It is possible that a tax-exempt shareholder will also recognize UBTI if a Fund recognizes excess inclusion income (as described above) derived from direct or indirect investments in residual interests in REMICs or equity interests in TMPs. Furthermore, any investment in residual interests of a CMO that has elected to be treated as a REMIC can create complex tax consequences, especially if the Fund has state or local governments or other tax-exempt organizations as shareholders.

In addition, special tax consequences apply to charitable remainder trusts (CRTs) that invest in regulated investment companies that invest directly or indirectly in residual interests in REMICs or equity interests in TMPs. Under legislation enacted in December 2006, a CRT, as defined in Section 664 of the Code, that realizes UBTI for a taxable year must pay an excise tax annually of an amount equal to such UBTI. Under IRS guidance issued in October 2006, a CRT will not recognize UBTI solely as a result of investing in a Fund to the extent that it recognizes excess inclusion income. Rather, if at any time during any taxable year a CRT (or one of certain other tax-exempt shareholders, such as the United States, a state or political subdivision, or an agency or instrumentality thereof, and certain energy cooperatives) is a record holder of a share in a Fund and the Fund recognizes excess inclusion income, then the Fund will be subject to a tax on that portion of its excess inclusion income for the taxable year that is allocable to such shareholders at the highest U.S. federal corporate income tax rate. The extent to which the IRS guidance remains applicable in light of the December 2006 legislation is unclear. To the extent permitted under the 1940 Act, each Fund may elect to specially allocate any such tax to the applicable CRT, or other shareholder, and thus reduce such shareholder’s distributions for the year by the amount of the tax that relates to such shareholder’s interest in the Fund. Each Fund has not yet determined whether such an election will be made. CRTs are urged to consult their tax advisors concerning the consequences of investing in a Fund.

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Tax Shelter Reporting Regulations

Under Treasury Regulations, if a shareholder recognizes a loss of $2 million or more for an individual shareholder or $10 million or more for a corporate shareholder, the shareholder must file with the IRS a disclosure statement on Form 8886. Direct shareholders of portfolio securities are in many cases excepted from this reporting requirement, but under current guidance, shareholders of a regulated investment company are not excepted. Future guidance may extend the current exception from this reporting requirement to shareholders of most or all regulated investment companies. The fact that a loss is reportable under these regulations does not affect the legal determination of whether the taxpayer’s treatment of the loss is proper. Shareholders should consult their tax advisors to determine the applicability of these regulations in light of their individual circumstances.

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CONTROL PERSONS AND PRINCIPAL SHAREHOLDERS

Management Ownership, Approximate as of October 8, 2012

As of October 8, 2012, the Trustees and the officers of the Trust, as a group, owned less than 1% of each class of the outstanding equity securities of each Fund, except as noted in the chart below, which identifies each Trustee and officer of the Trust that owns beneficially greater than 1% of the outstanding Class Z shares of a Fund.

	Columbia Acorn Emerging Markets Fund			Columbia Acorn European Fund			Columbia Thermostat Fund
Laura M. Born		1.69	%*		—			—
Maureen M. Culhane		—			1.09	%*		—
Charles P. McQuaid		10.57	%		14.15	%		1.55	%*
Ralph Wanger		—			—			2.21	%*
Robert A. Chalupnik		2.11	%		2.55	%		—
P. Zachary Egan		3.17	%		15.28	%		—
Fritz Kaegi		12.60	%		5.12	%		—
Stephen Kusmierczak		7.11	%		14.60	%		—
Bruce H. Lauer		1.06	%		2.55	%		—
Louis J. Mendes		5.28	%		5.09	%		—
Robert A. Mohn		2.11	%		2.55	%		—
Robert P. Scales		—			1.08	%		—
Andreas Waldburg-Wolfegg		2.66	%		12.58	%		—

* Approximate percentage based on ownership and outstanding Class Z shares of the Fund as of September 28, 2012.

Principal Holder Ownership as of October 8, 2012

As of October 8, 2012, the name, address and percentage of ownership of each person who may be deemed to be a “principal holder” (i.e., owns of record or is known by the Trust to own beneficially 5% or more of any class of a Fund’s outstanding shares) is listed below.

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Emerging Markets Fund Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		105,723.339		70.54	%
Columbia Acorn Emerging Markets Fund Class A	RAYMOND JAMES FBO OMNIBUS FOR MUTUAL FUNDS ATTN: COURTNEY WALLER 880 CARILLON PKWY ST PETERSBURG FL 33716-1100		14,857.737		9.91	%
Columbia Acorn Emerging Markets Fund Class A	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		11,320.356		7.55	%
Columbia Acorn Emerging Markets Fund Class A	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		7,793.071		5.20	%

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Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Emerging Markets Fund Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		12,246.146		42.76	%
Columbia Acorn Emerging Markets Fund Class C	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		7,753.290		27.07	%
Columbia Acorn Emerging Markets Fund Class C	STATE STREET BK & TR IRA JAMES P BOHNEY 8483 HICKORY HILL TRL MOORESVILLE IN 46158-8238		2,970.297		10.37	%
Columbia Acorn Emerging Markets Fund Class C	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		1,693.963		5.91	%
Columbia Acorn Emerging Markets Fund Class I	COLUMBIA MGMT INVESTMENT ADVSR LLC ATTN TIM ARMBRUSTMACHER 50807 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0508		500.310		100.00	%
Columbia Acorn Emerging Markets Fund Class Z	FREDERICK KAEGI C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		59,670.385		12.60	%
Columbia Acorn Emerging Markets Fund Class Z	RAYMOND JAMES FBO OMNIBUS FOR MUTUAL FUNDS ATTN: COURTNEY WALLER 880 CARILLON PKWY ST PETERSBURG FL 33716-1100		59,159.758		12.50	%
Columbia Acorn Emerging Markets Fund Class Z	CHARLES P MCQUAID TTEE CHARLES P MCQUAID TRUST C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		50,021.974		10.57	%
Columbia Acorn Emerging Markets Fund Class Z	STEPHEN KUSMIERCZAK TOD BENEFICIARY INFORMATION ON FILE C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		33,667.762		7.11	%
Columbia Acorn Emerging Markets Fund Class Z	LOUIS J MENDES III C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		25,010.987		5.28	%

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Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Emerging Markets Fund Class Z	BRUCE C CORWIN TTEE SWS LEASING DEFINED BENEFIT TRUST PO BOX 927 PLAINFIELD IL 60544-0927		23,733.687		5.01	%
Columbia Acorn European Fund Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		21,014.412		88.86	%
Columbia Acorn European Fund Class C	LPL FINANCIAL SERVICES 9785 TOWNE CENTRE DR SAN DIEGO CA 92121-1968		5,519.641		73.36	%
Columbia Acorn European Fund Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		1,501.017		19.95	%
Columbia Acorn European Fund Class C	COLUMBIA MGMT INVESTMENT ADVSR LLC ATTN TIM ARMBRUSTMACHER 50807 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0508		503.247		6.69	%
Columbia Acorn European Fund Class I	COLUMBIA MGMT INVESTMENT ADVSR LLC ATTN TIM ARMBRUSTMACHER 50807 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0508		505.538		100.00	%
Columbia Acorn European Fund Class Z	P ZACHARY EGAN TTEE P ZACHARY EGAN REVOCABLE TRUST C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		30,310.275		15.28	%
Columbia Acorn European Fund Class Z	STEPHEN KUSMIERCZAK TOD BENEFICIARY INFORMATION ON FILE C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		28,967.670		14.60	%
Columbia Acorn European Fund Class Z	CHARLES P MCQUAID TTEE CHARLES P MCQUAID TRUST C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		28,061.953		14.15	%
Columbia Acorn European Fund Class Z	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		23,952.003		12.07	%

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Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn European Fund Class Z	FREDERICK KAEGI C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		10,152.423		5.12	%
Columbia Acorn European Fund Class Z	DAVID L FRANK & TAMARA L SOKOLEC JT WROS 1704 W HENDERSON ST CHICAGO IL 60657-1034		10,103.426		5.09	%
Columbia Acorn European Fund Class Z	LOUIS J MENDES III C/O COLUMBIA WANGER ASSET MANAGEMENT, LLC 227 WEST MONROE STREET, SUITE 3000, CHICAGO, ILLINOIS 60606		10,103.426		5.09	%
Columbia Acorn Fund Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		16,861,143.505		15.39	%
Columbia Acorn Fund Class A	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		12,544,621.217		11.45	%
Columbia Acorn Fund Class A	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		6,118,780.117		5.58	%
Columbia Acorn Fund Class A	UBS WM USA ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		5,759,114.028		5.26	%
Columbia Acorn Fund Class A	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		5,527,994.388		5.05	%
Columbia Acorn Fund Class B	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		183,125.715		12.51	%
Columbia Acorn Fund Class B	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		174,407.104		11.91	%
Columbia Acorn Fund Class B	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		159,067.390		10.86	%

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Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Fund Class B	MERRILL LYNCH, PIERCE, FENNER & SMITH INC FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTENTION SERVICE TEAM 4800 DEER LAKE DRIVE EAST 3RD FLOOR JACKSONVILLE FL 32246-6484		143,754.247		9.82	%
Columbia Acorn Fund Class B	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		138,438.965		9.45	%
Columbia Acorn Fund Class B	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		125,648.155		8.58	%
Columbia Acorn Fund Class C	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		5,002,429.530		17.79	%
Columbia Acorn Fund Class C	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		3,584,968.370		12.75	%
Columbia Acorn Fund Class C	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		3,412,195.530		12.13	%
Columbia Acorn Fund Class C	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		2,779,102.814		9.88	%
Columbia Acorn Fund Class C	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		2,049,578.652		7.29	%
Columbia Acorn Fund Class C	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		1,930,756.534		6.87	%

126

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Fund Class C	RAYMOND JAMES FBO OMNIBUS FOR MUTUAL FUNDS ATTN: COURTNEY WALLER 880 CARILLON PKWY ST PETERSBURG FL 33716-1100		1,877,442.065		6.68	%
Columbia Acorn Fund Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		1,422,970.473		5.06	%
Columbia Acorn Fund Class I	COLUMBIA THERMOSTAT FUND C/O PAULA RYAN 227 W MONROE ST STE 3000 CHICAGO IL 60606-5018		1,259,676.907		99.99	%
Columbia Acorn Fund Class Z	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		48,559,308.343		11.30	%
Columbia Acorn Fund Class Z	CHARLES SCHWAB & CO INC ATTN MUTUAL FUND DEPT 101 MONTGOMERY ST SAN FRANCISCO CA 94104-4151		44,676,552.022		10.40	%
Columbia Acorn Fund Class Z	FIDELITY INVESTMENTS INST L OPS CO FIIOC AS AGENT FOR CERTAIN EMPLOYEE BENEFIT PLANS 100 MAGELLAN WAY # KW1C COVINGTON KY 41015-1999		44,605,322.458		10.38	%
Columbia Acorn Fund Class Z	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 3 JACKSONVILLE FL 32246-6484		36,212,536.806		8.43	%
Columbia Acorn Fund Class Z	STATE OF ILLINOIS EMPLOYEES DEFERRED COMP PLAN ATTN CHRIS SCHOFIELD PO BOX 19208 SPRINGFIELD IL 62794-9208		30,276,150.171		7.05	%
Columbia Acorn International Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		5,833,779.610		23.61	%
Columbia Acorn International Class A	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		5,148,932.020		20.84	%

127

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn International Class A	DCGT AS TTEE AND/OR CUST FBO PRINCIPAL FINANCIAL GROUP QUALI FIED FIA OMNIBUS ATTN NPIO TRADE DESK 711 HIGH ST DES MOINES IA 50392-0001		1,327,873.559		5.37	%
Columbia Acorn International Class B	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		81,398.641		16.70	%
Columbia Acorn International Class B	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		70,386.618		14.44	%
Columbia Acorn International Class B	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		34,232.851		7.02	%
Columbia Acorn International Class B	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		32,654.979		6.70	%
Columbia Acorn International Class B	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		30,876.470		6.33	%
Columbia Acorn International Class C	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		429,574.041		17.28	%
Columbia Acorn International Class C	RAYMOND JAMES FBO OMNIBUS FOR MUTUAL FUNDS ATTN: COURTNEY WALLER 880 CARILLON PKWY ST PETERSBURG FL 33716-1100		265,242.362		10.67	%
Columbia Acorn International Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		211,613.023		8.51	%
Columbia Acorn International Class C	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		207,986.211		8.37	%

128

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn International Class C	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		204,976.439		8.25	%
Columbia Acorn International Class C	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		200,410.649		8.06	%
Columbia Acorn International Class C	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		145,731.228		5.86	%
Columbia Acorn International Class I	COLUMBIA THERMOSTAT FUND 227 W MONROE ST STE 3000 CHICAGO IL 60606-5018		1,312,995.242		72.34	%
Columbia Acorn International Class I	RIVERSOURCE PORTFOLIO BUILDER MODERATE FUND 1767 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0001		145,573.949		8.02	%
Columbia Acorn International Class I	RIVERSOURCE PORTFOLIO BUILDER MODERATE AGGRESSIVE FUND 1767 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0001		141,582.948		7.80	%
Columbia Acorn International Class I	RIVERSOURCE PORTFOLIO BUILDER AGGRESSIVE FUND 1767 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0001		100,961.311		5.56	%
Columbia Acorn International Class R	MERRILL LYNCH, PIERCE, FENNER & SMITH INC FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTENTION SERVICE TEAM 4800 DEER LAKE DRIVE EAST 3RD FLOOR JACKSONVILLE FL 32246-6484		6,626.382		18.86	%
Columbia Acorn International Class R	STATE STREET CORPORATION 1 LINCOLN ST BOSTON MA 02111-2901		5,258.581		14.97	%
Columbia Acorn International Class R	MG TRUST CO CUST FBO OHIO STATE UNIVERSITY 403 B PLAN 700 17TH ST STE 300 DENVER CO 80202-3531		3,651.763		10.39	%
Columbia Acorn International Class R	FRONTIER TRUST COMPANY FBO U.S. TANK ALLIANCE, INC 401(K) P/S PO BOX 10758 FARGO ND 58106-0758		2,179.506		6.20	%

129

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn International Class R	MG TRUST COMPANY CUST. FBO NORTHCENTRAL UNIVERSITY, INC. 401(K 700 17TH ST STE 300 DENVER CO 80202-3531		2,030.757		5.78	%
Columbia Acorn International Class R	FRONTIER TRUST COMPANY FBO B & L CORPORATION 401(K) PLAN PO BOX 10758 FARGO ND 58106-0758		1,899.691		5.41	%
Columbia Acorn International Class R5	CHARLES SCHWAB & CO INC SPECIAL CUSTODY ACCOUNT FOR THE EXCLUSIVE BENEFIT OF CUSTOMERS ATTN MUTUAL FUNDS 101 MONTGOMERY STREET SAN FRANCISCO CA 94104-4151		7,058.559		88.91	%
Columbia Acorn International Class R5	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		640.984		8.07	%
Columbia Acorn International Class Z	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 3 JACKSONVILLE FL 32246-6484		24,082,683.996		18.14	%
Columbia Acorn International Class Z	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		19,836,550.637		14.94	%
Columbia Acorn International Class Z	CHARLES SCHWAB & COMPANY MUTUAL FUND DEPT 101 MONTGOMERY ST SAN FRANCISCO CA 94104-4151		16,340,534.390		12.31	%
Columbia Acorn International Class Z	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		6,864,087.977		5.17	%
Columbia Acorn International Select Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		852,914.223		37.29	%
Columbia Acorn International Select Class A	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		195,589.539		8.55	%

130

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn International Select Class A	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		120,684.729		5.28	%
Columbia Acorn International Select Class A	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		118,831.451		5.20	%
Columbia Acorn International Select Class B	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		9,117.998		18.88	%
Columbia Acorn International Select Class B	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		7,503.480		15.54	%
Columbia Acorn International Select Class B	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		6,494.828		13.45	%
Columbia Acorn International Select Class B	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		5,698.540		11.80	%
Columbia Acorn International Select Class B	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		5,141.599		10.65	%
Columbia Acorn International Select Class B	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		4,850.110		10.04	%
Columbia Acorn International Select Class C	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		47,546.481		14.10	%
Columbia Acorn International Select Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		42,156.367		12.50	%
Columbia Acorn International Select Class C	RAYMOND JAMES FBO OMNIBUS FOR MUTUAL FUNDS ATTN: COURTNEY WALLER 880 CARILLON PKWY ST PETERSBURG FL 33716-1100		38,473.838		11.41	%

131

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn International Select Class C	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		35,033.724		10.39	%
Columbia Acorn International Select Class C	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		29,530.675		8.76	%
Columbia Acorn International Select Class C	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		28,043.651		8.31	%
Columbia Acorn International Select Class C	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		21,849.544		6.48	%
Columbia Acorn International Select Class I	RIVERSOURCE INVESTMENTS LLC ATTN T ARMBRUSTMACHER & V GEHLHAR 50807 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0508		95.749		100.00	%
Columbia Acorn International Select Class Z	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 3 JACKSONVILLE FL 32246-6484		5,412,237.970		49.81	%
Columbia Acorn International Select Class Z	CHARLES SCHWAB & CO INC CUSTODY ACCOUNT FOR BENEFIT OF OUR CUSTOMERS ATTN MUTUAL FUND DEPT 101 MONTGOMERY ST SAN FRANCISCO CA 94104-4151		1,143,502.567		10.52	%
Columbia Acorn International Select Class Z	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		899,643.153		8.28	%
Columbia Acorn International Select Class Z	FIDELITY INVESTMENTS INST L OPS CO FIIOC AS AGENT FOR CERTAIN EMPLOYEE BENEFIT PLANS 100 MAGELLAN WAY COVINGTON KY 41015-1999		553,106.148		5.09	%

132

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Select Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		2,870,898.582		25.02	%
Columbia Acorn Select Class A	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		830,322.953		7.24	%
Columbia Acorn Select Class A	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		747,754.543		6.52	%
Columbia Acorn Select Class A	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		640,514.387		5.58	%
Columbia Acorn Select Class A	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		594,542.904		5.18	%
Columbia Acorn Select Class B	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		90,632.307		16.28	%
Columbia Acorn Select Class B	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		78,776.128		14.15	%
Columbia Acorn Select Class B	MERRILL LYNCH, PIERCE, FENNER & SMITH INC FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTENTION SERVICE TEAM 4800 DEER LAKE DRIVE EAST 3RD FLOOR JACKSONVILLE FL 32246-6484		78,632.024		14.12	%
Columbia Acorn Select Class B	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		51,464.078		9.24	%
Columbia Acorn Select Class B	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		45,341.921		8.14	%

133

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Select Class B	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		37,598.234		6.75	%
Columbia Acorn Select Class C	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		465,451.316		18.29	%
Columbia Acorn Select Class C	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		335,373.352		13.18	%
Columbia Acorn Select Class C	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		289,422.493		11.37	%
Columbia Acorn Select Class C	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		255,219.415		10.03	%
Columbia Acorn Select Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		177,109.392		6.96	%
Columbia Acorn Select Class C	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		174,665.449		6.86	%
Columbia Acorn Select Class C	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		131,476.369		5.17	%
Columbia Acorn Select Class I	COLUMBIA THERMOSTAT FUND C/O PAULA RYAN 227 W MONROE ST STE 3000 CHICAGO IL 60606-5018		987,200.583		99.99	%
Columbia Acorn Select Class Z	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 3 JACKSONVILLE FL 32246-6484		5,337,873.240		20.51	%

134

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn Select Class Z	CHARLES SCHWAB & CO INC CUSTODY ACCOUNT FOR BENEFIT OF OUR CUSTOMERS ATTN MUTUAL FUND DEPT 101 MONTGOMERY ST SAN FRANCISCO CA 94104-4151		4,314,122.667		16.58	%
Columbia Acorn Select Class Z	FIDELITY INVESTMENTS INST L OPS CO FIIOC AS AGENT FOR CERTAIN EMPLOYEE BENEFIT PLANS 100 MAGELLAN WAY # KW1C COVINGTON KY 41015-1999		3,257,381.502		12.52	%
Columbia Acorn Select Class Z	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		3,112,537.552		11.96	%
Columbia Acorn USA Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		670,049.982		13.15	%
Columbia Acorn USA Class A	MERRILL LYNCH LIFE INSURANCECOMPANY INVESTORS CHOICE IRA 4333 EDGEWOOD RD NE # MS4410 CEDAR RAPIDS IA 52499-0001		481,900.572		9.45	%
Columbia Acorn USA Class A	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		362,537.425		7.11	%
Columbia Acorn USA Class A	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		352,413.800		6.91	%
Columbia Acorn USA Class A	NEW YORK LIFE TRUST COMPANY 690 CANTON ST STE 100 WESTWOOD MA 02090-2344		277,101.732		5.44	%
Columbia Acorn USA Class B	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		7,924.421		14.55	%

135

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn USA Class B	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		7,680.933		14.10	%
Columbia Acorn USA Class B	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		5,881.689		10.80	%
Columbia Acorn USA Class B	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		3,716.816		6.83	%
Columbia Acorn USA Class B	STATE STREET BK & TR IRA TRONG D NGUYEN 8131 DAVENTREE DR BRECKSVILLE OH 44141-1272		3,132.659		5.75	%
Columbia Acorn USA Class B	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		3,054.985		5.61	%
Columbia Acorn USA Class C	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		554,025.082		46.69	%
Columbia Acorn USA Class C	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		102,226.651		8.62	%
Columbia Acorn USA Class C	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		93,718.431		7.90	%
Columbia Acorn USA Class C	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		72,919.603		6.15	%
Columbia Acorn USA Class C	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		64,824.942		5.46	%
Columbia Acorn USA Class I	RIVERSOURCE INVESTMENTS LLC ATTN T ARMBRUSTMACHER & V GEHLHAR 50807 AMERIPRISE FINANCIAL CTR MINNEAPOLIS MN 55474-0508		103.135		100.00	%

136

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Acorn USA Class Z	FIDELITY INVESTMENTS INST L OPS CO FIIOC AS AGENT FOR CERTAIN EMPLOYEE BENEFIT PLANS 100 MAGELLAN WAY # KW1C COVINGTON KY 41015-1999		12,089,279.111		26.63	%
Columbia Acorn USA Class Z	CHARLES SCHWAB & CO INC CUSTODY ACCOUNT FOR BENEFIT OF OUR CUSTOMERS ATTN MUTUAL FUND DEPT 101 MONTGOMERY ST SAN FRANCISCO CA 94104-4151		8,267,843.688		18.21	%
Columbia Acorn USA Class Z	MAC & CO FBO NY STATE DEFERRED COMP PLAN ATTN MUTUAL FUNDS OPERATIONS P.O. BOX 3198 525 WILLIAM PENN PLACE PITTSBURGH PA 15230-3198		6,661,415.364		14.67	%
Columbia Acorn USA Class Z	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 3 JACKSONVILLE FL 32246-6484		4,149,869.522		9.14	%
Columbia Acorn USA Class Z	VANGUARD FIDUCIARY TRUST COMPANY LIBERTY ACORN USA PO BOX 2600 VALLEY FORGE PA 19482-2600		2,551,202.182		5.62	%
Columbia Thermostat Fund Class A	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		4,975,530.417		28.62	%
Columbia Thermostat Fund Class A	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		3,185,004.290		18.32	%
Columbia Thermostat Fund Class A	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		1,799,467.146		10.35	%
Columbia Thermostat Fund Class A	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		1,197,411.040		6.89	%

137

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Thermostat Fund Class A	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		1,042,589.055		6.00	%
Columbia Thermostat Fund Class A	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		925,582.163		5.32	%
Columbia Thermostat Fund Class B	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		76,788.249		21.55	%
Columbia Thermostat Fund Class B	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		54,231.641		15.22	%
Columbia Thermostat Fund Class B	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		35,897.771		10.07	%
Columbia Thermostat Fund Class B	NATIONAL FINANCIAL SERVICES LLC FEBO CUSTOMERS MUTUAL FUNDS 200 LIBERTY STREET 1WFC NEW YORK NY 10281-1003		33,054.754		9.28	%
Columbia Thermostat Fund Class B	PERSHING LLC 1 PERSHING PLAZA JERSEY CITY NJ 07399-0002		24,389.824		6.84	%
Columbia Thermostat Fund Class C	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 2 JACKSONVILLE FL 32246-6484		3,613,401.714		28.27	%
Columbia Thermostat Fund Class C	AMERICAN ENTERPRISE INVESTMENT SVC 707 2ND AVE S MINNEAPOLIS MN 55402-2405		2,217,000.745		17.35	%
Columbia Thermostat Fund Class C	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		1,449,411.031		11.34	%

138

Fund	Shareholder Account Registration	Share Balance		Percentage of Class
Columbia Thermostat Fund Class C	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		1,228,267.865		9.61	%
Columbia Thermostat Fund Class C	UBS WM USA OMNI ACCOUNT M/F ATTN: DEPARTMENT MANAGER 1000 HARBOR BLVD WEEHAWKEN NJ 07086-6761		811,840.461		6.35	%
Columbia Thermostat Fund Class Z	MERRILL LYNCH, PIERCE, FENNER & SMITH INC FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTENTION SERVICE TEAM 4800 DEER LAKE DRIVE EAST 3RD FLOOR JACKSONVILLE FL 32246-6484		5,903,846.898		35.35	%
Columbia Thermostat Fund Class Z	MORGAN STANLEY SMITH BARNEY HARBORSIDE FINANCIAL CENTER PLAZA 2, 3RD FLOOR JERSEY CITY NJ 07311		2,791,107.101		16.71	%
Columbia Thermostat Fund Class Z	FIRST CLEARING LLC SPECIAL CUSTODY ACCT FOR THE EXCLUSIVE BENEFIT OF CUSTOMER 2801 MARKET ST SAINT LOUIS MO 63103-2523		2,435,219.200		14.58	%
Columbia Thermostat Fund Class Z	LPL FINANCIAL 9785 TOWNE CENTRE DR SAN DIEGO CA 92121-1968		1,204,024.127		7.21	%

Control Person Ownership as of October 8, 2012

As of October 8, 2012, the name, address and percentage of ownership of each person who may be deemed to be a “control person” (as that term is defined in the 1940 Act) of a Fund because it owns greater than 25% of the outstanding shares, either beneficially or by virtue of its fiduciary or trust roles or otherwise, is shown below. A controlling person’s vote could have a more significant effect on matters presented to shareholders for approval than the vote of other Fund shareholders.

Fund	Shareholder Account Registration	Share Balance		Percentage of Fund
Columbia Acorn International Select	MERRILL LYNCH PIERCE FENNER & SMITH FOR THE SOLE BENEFIT OF ITS CUSTOMERS ATTN FUND ADMINISTRATION 4800 DEER LAKE DR E FL 3 JACKSONVILLE FL 32246-6484		5,446,910.24		40.24	%

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APPENDIX A — DESCRIPTIONS OF SECURITIES RATINGS

This Appendix summarizes the various descriptions of securities ratings applicable to securities purchased by the Columbia Funds Family. Please refer to a Fund’s prospectus and this statement of additional information to determine whether the Fund may invest in securities that have ratings described in this Appendix.

STANDARD & POOR’S (S&P)

Bonds

The following summarizes the ratings used by S&P for bonds. The ratings AAA, AA, A and BBB denote investment grade securities.

AAA bonds have the highest rating assigned by S&P and are considered to have an extremely strong capacity to pay interest and repay principal.

AA bonds are considered to have a very strong capacity to pay interest and repay principal, and they differ from AAA only in small degree.

A bonds are considered to have a strong capacity to pay interest and repay principal, although they are somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than debt in higher rated categories.

BBB bonds are considered to have an adequate capacity to pay interest and repay principal. Whereas they normally exhibit adequate protection parameters, adverse economic conditions or changing circumstances are more likely to lead to a weakened capacity to pay interest and repay principal than for bonds in the A category.

BB, B, CCC, CC and C bonds are considered to have predominantly speculative characteristics with respect to capacity to pay interest and repay principal in accordance with the terms of the obligation. BB indicates the lowest degree of speculation and C the highest degree. While such debt will likely have some quality and protective characteristics, these are outweighed by large uncertainties or large exposures to adverse conditions.

BB bonds are considered to have less near-term vulnerability to default than other speculative issues. However, they face major ongoing uncertainties or exposure to adverse business, financial, or economic conditions which could lead to inadequate capacity to meet timely interest and principal payments. The BB rating category is also used for debt subordinated to senior debt that is assigned an actual or implied BBB — rating.

B bonds are considered to have a greater vulnerability to default but currently have the capacity to meet interest payments and principal repayments. Adverse business, financial, or economic conditions will likely impair capacity or willingness to pay interest and repay principal. The B rating category is also used for debt subordinated to senior debt that is assigned an actual or implied BB or BB — rating.

CCC bonds are considered to have a currently identifiable vulnerability to default, and are dependent upon favorable business, financial, and economic conditions to meet timely payment of interest and repayment of principal. In the event of adverse business, financial, or economic conditions, the bonds are not likely to have the capacity to pay interest and repay principal. The CCC rating category is also used for debt subordinated to senior debt that is assigned an actual or implied B or B — rating.

CC rating typically is applied to debt subordinated to senior debt that is assigned an actual or implied CCC rating.

C rating typically is applied to debt subordinated to senior debt that is assigned an actual or implied CCC — debt rating. The C rating may be used to cover a situation, for example, where a bankruptcy petition has been filed, but debt service payments are continued.

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CI rating is reserved for income bonds on which no interest is being paid.

D bonds are in payment default. The D rating category is used when interest payments or principal payments are not made on the date due even if the applicable grace period has not expired, unless S&P believes that such payments will be made during such grace period. The D rating also will be used upon the filing of a bankruptcy petition if debt service payments are jeopardized.

Plus (+) or minus (-): The ratings from AA to CCC may be modified by the addition of a plus or minus sign to show relative standing within the major rating categories.

Municipal Notes

SP-1. Notes rated SP-1 are considered to have very strong or strong capacity to pay principal and interest. Those issues determined to possess overwhelming safety characteristics are designated as SP-1+.

SP-2. Notes rated SP-2 are considered to have satisfactory capacity to pay principal and interest.

Notes due in three years or less normally receive a note rating. Notes maturing beyond three years normally receive a bond rating, although the following criteria are used in making that assessment:

Amortization schedule (the larger the final maturity relative to other maturities, the more likely the issue will be rated as a note).

Source of payment (the more dependent the issue is on the market for its refinancing, the more likely it will be rated as a note).

Commercial Paper

A. Issues assigned this highest rating are regarded as having the greatest capacity for timely payment. Issues in this category are further refined with the designations 1, 2, and 3 to indicate the relative degree of safety.

A-1. Issues assigned to this rating are considered to have overwhelming or very strong capacity for timely payment. Those issues determined to possess overwhelming safety characteristics are designed A-1+.

MOODY’S INVESTORS SERVICE, INC. (MOODY’S)

Municipal Bonds

Aaa bonds are considered to be of the best quality. They are considered to have the smallest degree of investment risk and are generally referred to as ‘‘gilt edge’’. Interest payments are protected by a large or by an exceptionally stable margin and principal is secure. While various protective elements are likely to change, such changes as can be visualized are most unlikely to impair a fundamentally strong position of such issues.

Aa bonds are considered to be of high quality by all standards. Together with Aaa bonds they comprise what are generally known as high-grade bonds. They are rated lower than the best bonds because margins of protection may not be as large in Aaa securities or fluctuation of protective elements may be of greater amplitude or there may be other elements present which make the long-term risks appear somewhat larger than in Aaa securities. Those bonds in the Aa through B groups that Moody’s believes possess the strongest investment attributes are designated by the symbols Aa1, A1 or Baa1.

A bonds are considered to possess many favorable investment attributes and are to be considered to be upper-medium-grade obligations. Factors giving security to principal and interest are considered adequate, but elements may be present that suggest a susceptibility to impairment at some time in the future.

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Baa bonds are considered to be medium grade obligations: they are neither highly protected nor poorly secured. Interest payments and principal security appear adequate for the present but certain protective elements may be lacking or may be characteristically unreliable over any great period of time. Such bonds lack outstanding investment characteristics and, in fact, have speculative characteristics as well.

Ba bonds are considered to have speculative elements: their future cannot be considered as well secured. Often, the protection of interest and principal payments may be very moderate and thereby not well safeguarded during both good and bad times in the future. Uncertainty of position characterizes bonds in this grade.

B bonds are considered generally to lack characteristics of a desirable investment. Assurance of interest and principal payments or of maintenance of other terms of the contract over any long period of time may be small.

Caa bonds are considered to be of poor standing. Such issues may be in default or there may be present elements of danger with respect to principal or interest.

Ca bonds are considered to represent obligations that are speculative in a high degree. Such issues are often in default or have other marked shortcomings.

C bonds are the lowest rated class of bonds and issues so rated are considered to have extremely poor prospects of ever attaining any real investment standing.

Conditional Ratings. Bonds for which the security depends upon the completion of some act or the fulfillment of some condition are rated conditionally. These are bonds secured by (a) earnings of projects under construction, (b) earnings of projects unseasoned in operating experience, (c) rentals which begin when facilities are completed, or (d) payments to which some other limiting conditions attach. Parenthetical rating denotes probable credit stature upon completion of construction or elimination of basis of condition.

Corporate Bonds

The description of the applicable rating symbols (Aaa, Aa, A, Baa, etc.) and their meanings is identical to that of the Municipal Bond ratings as set forth above, except for the numerical modifiers. Moody’s applies numerical modifiers 1, 2, and 3 in the Aa and A classifications of its corporate bond rating system. The modifier 1 indicates that the security ranks in the higher end of its generic rating category; the modifier 2 indicates a midrange ranking; and the modifier 3 indicates that the issuer ranks in the lower end of its generic rating category.

Municipal Notes

MIG 1. This designation denotes best quality. There is present strong protection by established cash flows, superior liquidity support or demonstrated broad-based access to the market for refinancing.

MIG 2. This designation denotes high quality. Margins of protection are ample although not so large as in the preceding group.

MIG 3. This designation denotes favorable quality. All security elements are accounted for, but there is lacking the undeniable strength of the preceding grades. Liquidity and cash flow protection may be narrow and market access for refinancing is likely to be less well established.

Commercial Paper

Moody’s employs the following three designations, all judged to be investment grade, to indicate the relative repayment capacity of rated issuers:

Prime-1 Highest Quality

A-3

Prime-2 Higher Quality

Prime-3 High Quality

If an issuer represents to Moody’s that its commercial paper obligations are supported by the credit of another entity or entities, Moody’s, in assigning ratings to such issuers, evaluates the financial strength of the indicated affiliated corporations, commercial banks, insurance companies, foreign governments, or other entities, but only as one factor in the total rating assessment.

FITCH, INC. (FITCH)

Long-Term Debt

Investment Grade Bond Ratings

AAA bonds are considered to be investment grade and of the highest credit quality. The obligor has an exceptionally strong ability to pay interest and/or dividends and repay principal, which is unlikely to be affected by reasonably foreseeable events.

AA bonds are considered to be investment grade and of very high credit quality. The obligor’s ability to pay interest and repay principal is very strong, although not quite as strong as bonds rated AAA. Because bonds rated in the AAA and AA categories are not significantly vulnerable to foreseeable future developments, short-term debt of these issuers is generally rated F-1+.

A bonds are considered to be investment grade and of high credit quality. The obligor’s ability to pay interest and repay principal is considered to be strong, but may be more vulnerable to adverse changes in economic conditions and circumstances than debt securities with higher ratings.

BBB bonds are considered to be investment grade and of satisfactory credit quality. The obligor’s ability to pay interest or dividends and repay principal is considered to be adequate. Adverse changes in economic conditions and circumstances, however, are more likely to have adverse impact on these securities and, therefore, impair timely payment. The likelihood that the ratings of these bonds will fall below investment grade is higher than for securities with higher ratings.

Speculative Grade Bond Ratings

BB bonds are considered speculative. The obligor’s ability to pay interest and repay principal may be affected over time by adverse economic changes. However, business and financial alternatives can be identified, which could assist the obligor in satisfying its debt service requirements.

B bonds are considered highly speculative. While securities in this class are currently meeting debt service requirements, the probability of continued timely payment of principal and interest reflects the obligor’s limited margin of safety and the need for reasonable business and economic activity throughout the life of the issue.

CCC bonds are considered to have certain identifiable characteristics that, if not remedied, may lead to default. The ability to meet obligations requires an advantageous business and economic environment.

CC bonds are considered to be minimally protected. Default in payment of interest and/or principal seems probable over time.

C bonds are in imminent default in payment of interest or principal.

DDD, DD, and D bonds are in default on interest and/or principal payments. Such securities are extremely speculative and should be valued on the basis of their ultimate recovery value in liquidation or reorganization of the obligor. DDD represents the highest potential for recovery on these securities and D represents the lowest potential for recovery.

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Plus (+) or minus (-): Plus or minus signs are used to show relative standing within the major rating categories. Plus and minus signs, however, are not used in the DDD, DD, or D categories.

Short-Term Debt

Fitch’s short-term ratings apply to debt obligations that are payable on demand or have original maturities of up to three years, including commercial paper, certificates of deposit, medium-term notes, and investment notes.

F-1+ obligations have exceptionally strong credit quality and are considered to have the strongest degree of assurance for timely payment.

F-1 obligations are considered to reflect an assurance of timely payment only slightly less in degree than issues rated F-1+.

F-2 obligations are considered to have good credit quality. Securities in this class have a satisfactory degree of assurance for timely payment, but the margin of safety is not as great as for issues assigned F-1+ and F-1 ratings.

F-3 obligations are considered to have characteristics suggesting that the degree of assurance for timely payment is adequate; however, near-term adverse changes could cause these securities to be rated below investment grade.

F-S rating is assigned to obligations that are considered to have a minimal degree of assurance for timely payment and to be vulnerable to near-term adverse changes in financial and economic conditions.

B obligations are considered to have a minimal capacity for timely payment of financial commitments and a susceptibility to the adverse effects of changes in circumstances and economic conditions.

C rating is assigned to obligations that are considered to have a high default risk and whose capacity for meeting financial commitments is solely reliant upon a sustained, favorable business and economic environment.

D obligations are in actual or imminent payment default.

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APPENDIX B — THE INVESTMENT MANAGER’S PROXY VOTING POLICY AND PROCEDURES MANUAL

Columbia Wanger Asset Management, LLC (“CWAM”)

Proxy Policy and Procedures Manual

A. ADMINISTRATION

VOTING CLIENT AND FUND PROXIES

Primary Responsibility	CWAM Stock Analyst/Portfolio Manager
Secondary Responsibility	CWAM Chief Investment Officer
Oversight Responsibility	CWAM Chief Operating Officer and Chief Compliance Officer
Issue Date	8/01/03; as amended on 4/09/10, 12/08/10, 8/22/11 and 8/25/11

POLICY:

All proxies for client securities for which Columbia Wanger Asset Management, LLC (“CWAM”) has been granted authority to vote shall be voted in a manner considered to be in the best interests of CWAM’s clients, including the Columbia Acorn Funds (“Acorn”) and Wanger Advisor Trust Funds (“WAT”) and their shareholders, without regard to any benefit to CWAM or its affiliates. Where CWAM retains voting authority, as for most client securities, CWAM shall examine each recommendation and vote against management’s recommendation, if, in its judgment, approval or adoption of the recommendation would be expected to impact adversely the current or potential market value of the issuer’s securities. References to the best interest of a client refer to the interest of the client in terms of the potential economic return on the client’s investment. In the event a client believes that its other interests require a different vote, CWAM shall vote as the client instructs. In limited cases where in CWAM is required to adhere to regulatory restrictions over ownership limits of certain securities, CWAM may delegate voting authority to an independent third party to vote in the shareholders best interest.

CWAM addresses potential material conflicts of interest by having each individual stock analyst review and vote each proxy for the stocks that he/she follows. For those proposals where the analyst is voting against management’s recommendation or where there is a variance from the guidelines contained herein, the CWAM Proxy Committee will determine the vote in the best interest of CWAM’s clients, without consideration of any benefit to CWAM, its affiliates or its other clients.

OVERVIEW:

CWAM’s policy is based upon its fiduciary obligation to act in its clients’ best interests and rules under the Investment Company Act of 1940 and the Investment Advisers Act of 1940, which impose obligations with respect to proxy voting on investment advisers and investment companies.

PROCEDURES:

I.    ACCOUNT POLICIES

Except as otherwise directed by the client, CWAM or ISS, an independent third party delegated to vote in place of CWAM, shall vote as follows:

Separately Managed Accounts

CWAM or ISS shall vote proxies on securities held in its separately managed accounts where the client has given CWAM proxy voting authority. CWAM currently has authority to vote proxies for the Fairfax County

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Employees’ Retirement System and Fleet Boston Financial Pension Plan but does not have authority to vote proxies for the State of Oregon or the 1199 SEIU Healthcare Employees Pension Fund.

Columbia Acorn Trust/Wanger Advisors Trust

CWAM or ISS shall vote proxies for portfolio securities held in the Acorn and WAT funds.

Columbia Thermostat Fund

To avoid any potential conflict of interest CWAM shall vote “echo vote” proxies for Columbia Thermostat Fund. Echo voting means that CWAM will vote the shares in the same proportion as the other shareholders of those funds.

CWAM Offshore Funds

CWAM or ISS shall vote proxies on securities held in the Wanger Investment Company PLC (Wanger US Smaller Companies and Wanger European Smaller Companies).

CWAM Subadvised Mutual Fund Accounts

The authority to vote proxies on securities held in various RiverSource Funds is reserved to the client. CWAM or ISS has authority to vote proxies on securities held in the Optimum Small Cap Growth Fund.

II.    PROXY COMMITTEE

CWAM has established a Proxy Committee, which consists of the Chief Investment Officer, the Chief Operating Officer and the Director of Accounting and Operations. The Chief Compliance Officer of CWAM serves as a non-voting member. For proxy voting purposes only, the Proxy Committee will also include the analyst who follows the portfolio security on which to be voted. The director of domestic research may serve as an alternate member for proxy voting purposes and to break a voting tie.

The functions of the Proxy Committee shall include, in part,

(a) determine proxy votes as warranted under CWAM’s Proxy Voting Policy.

(b) annual review of this Policy and Procedures Manual to ensure consistency with internal policies and legal and regulatory requirements,

(c) annual review of existing Voting Guidelines and development of additional Voting Guidelines to assist in the review of proxy proposals, and

(d) development and modification of Voting Procedures as it deems appropriate or necessary.

In determining the vote on any proposal for which it has responsibility, the Proxy Committee shall act in accordance with the policy stated above.

The Proxy Committee shall create a charter, which shall be consistent with this policy and procedure. The charter shall set forth the Committee’s purpose, membership and operation. The charter shall include procedures prohibiting a member from voting on a matter for which he or she has a conflict of interest by reason of a direct relationship with the issuer or other party affected by a given proposal, e.g., is a portfolio manager for an account of the issuer.

The Proxy Committee shall furnish to the trustees of Columbia Acorn Trust and of Wanger Advisors Trust copies of any modifications of this Policy and Procedures Manual (including any modification of the Voting Guidelines or Voting Procedures).

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III.    VOTING GUIDELINES

Except under limited circumstances (described in Section IV) where CWAM delegates voting power to ISS, the stock analyst who follows the stock reviews all proxies and ballot items for which CWAM has authority to vote. The analyst will consider the views of management on each proposal, and if these views are consistent with the CWAM Proxy Policy, will vote in favor of management. However, each analyst has the responsibility of independently analyzing each proposal and voting each proxy item on a case-by-case basis. CWAM votes, to the best of its ability, all proxies for which it receives ballots.

Following are some guidelines CWAM uses with respect to voting on specific matters:

Election of the Board of Directors

CWAM supports management’s recommendation for proposals for the election of directors or for an increase or decrease in the number of directors provided a majority of directors would be independent. When director elections are contested, the analyst’s recommendation and vote should be forwarded to the Proxy Committee for a full vote.

Approval of Independent Auditors

CWAM will generally support management in its annual appointment or approval of independent corporate auditors. An auditor will usually be thought of as independent unless the auditor receives more than 50% of its revenues from non-audit, non-tax, activities from the company and its affiliates. In those cases, the vote should be forwarded to the Proxy Committee for a full vote.

Compensation and Equity-Based Compensation Plans

While CWAM recognizes companies need to compete for talent, CWAM is generally opposed to compensation plans that substantially dilute ownership interest in a company, provide participants with excessive awards, or have inherently objectionable structural features. Specifically, for equity-based plans, if the proposed number of shares authorized for stock incentive or option programs (excluding authorized shares of expired or exercised options) exceed 10% of the currently outstanding shares overall or 3% for directors only, the proposal should be referred to the Proxy Committee. The Committee will then consider the circumstances surrounding the issue and vote in the best interests of the client.

Stock Purchase Plans

CWAM is generally in favor of employee stock purchase plans where employees are able to purchase stock at or near the market price. Except when excessive dilution is proposed analysts should vote in favor of these proposals without consulting the Proxy Committee.

Advisory Votes on Executive Compensation

CWAM is generally in favor of proposals to ratify executive compensation unless total compensation obviously appears excessive. In such instances analyst should vote against such proposals without referring them to the Proxy Committee.

CWAM will generally vote against proposals to ratify Golden Parachutes without referring them to the Proxy Committee.

CWAM analyst will vote on the frequency of advisory votes on executive compensation on a case-by-case basis without referring them to the Proxy Committee. However, when CWAM votes against executive compensation analyst should vote for annual advisory votes.

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Corporate Governance Issues

CWAM will generally support resolutions to improve shareholder democracy and reduce the likelihood of management entrenchment or conflict-of-interest. All matters relating to corporate governance will be voted by CWAM on a case-by-case basis using this basic premise. Analyst should vote in favor of proxy items under this premise without consulting the Proxy Committee. If an Analyst is uncertain or believes that a vote should be made contrary to this premise, then the recommendation should be brought to the Proxy Committee for a full vote.

Social and Corporate Responsibility Issues

CWAM believes that “ordinary business matters” are primarily the responsibility of management and should be approved solely by the corporation’s board of directors. However, proposals regarding social issues initiated by shareholders asking the company to disclose or amend certain business practices will be analyzed by the appropriate CWAM stock analyst and evaluated on a case-by-case basis. If an analyst believes that a vote against management is appropriate, he/she should refer the proposal to the full vote by the Proxy Committee.

“Blank Check” Proposals

Occasionally proxy statements ask that shareholders allow proxies to approve any other items in a “blank check” manner. Analysts should vote against such proposals without referring those to the Proxy Committee.

Majority Election Requirement for Directors

Occasionally proxy statements ask the shareholders to vote on whether to require a majority vote in the case of election of directors. Analysts should vote in favor of these proposals without consulting the Proxy Committee.

Abstention Votes

Voting proxies with respect to shares of foreign stocks may involve significantly greater effort and corresponding cost due to the variety of regulatory schemes and corporate practices in foreign countries. Oftentimes, there may be language barriers, which will mean that an English translation of proxy information may not be available. Or, a translation must be obtained or commissioned before the relevant shareholder meeting. Time frames between shareholder notification, distribution of proxy materials, book-closure and the actual meeting date may be too short to allow timely action. In situations like these and in others where CWAM believes that it is uncertain with regards to the information received or because the cost of voting a proxy could exceed the expected benefit, the CWAM analyst may elect to abstain from voting. If an analyst believes that an abstention vote is appropriate, he/she should refer the proposal to the full vote by the Proxy Committee.

Special Issues Voting Foreign Proxies

To vote shares in some countries, shares must be “blocked” by the custodian or depository for a specified number of days before the shareholder meeting. Blocked shares typically may not be traded until the day after the shareholder meeting. CWAM may refrain from voting a portion or all shares of foreign stocks subject to blocking restrictions where, in the judgment of the CWAM analyst, the benefit from voting the shares is outweighed by the interest of maintaining client liquidity in the shares. The decision to vote/not vote is made by the CWAM analyst and is generally made on a case-by-case basis based on relevant factors, including the length of the blocking period, the significance of the holding, and whether the stock is considered a long-term holding.

In cases where the CWAM analyst determines that CWAM should not vote a portion or all foreign proxy shares due to blocking markets, the CWAM librarian (or a substitute) should document the reasons for not voting the proxy.

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IV.    VOTING PROCEDURES

The Proxy Committee has developed the following procedures to assist in the voting of proxies according to the Voting Guidelines set forth in Section III above. The Proxy Committee may revise these procedures from time to time, as it deems appropriate or necessary to effect the purposes of this Policy and Procedures.

For Columbia Acorn Trust and Wanger Advisors Trust

• CWAM shall use Institutional Shareholder Services (“ISS”), a third party vendor, to implement its proxy voting process. ISS shall provide record keeping services. ISS also will provide its internally generated proxy analysis, which can be used to help supplement the CWAM analyst’s research in the proxy voting process. In limited instances as described later in this section, CWAM may delegate voting power to ISS.

• On a daily basis, the funds’ custodian shall send ISS a holding file detailing each domestic equity holding held in the funds. Information on equity holdings for the international portfolio shall be sent weekly.

• ISS shall receive proxy material information from Proxy Edge or J.P. Morgan Chase Bank, N.A. for the funds. This shall include issues to be voted upon, together with a breakdown of holdings for the funds.

• Whenever a vote is solicited, ISS shall send CWAM a request to vote over a secure website. The CWAM librarian (or a substitute) will be responsible to check this website daily. The librarian will forward all materials to the appropriate CWAM analyst, who will review and complete the proxy ballot and return to the CWAM librarian or will refer one or more proposals to the Proxy Committee. The analyst will keep documentation (usually copies of email correspondence) of any proposals brought before the Proxy Committee and will instruct the CWAM librarian to vote the proposal in accordance with the Proxy Committee decision. The analyst will file Proxy Committee documentation under G:\Shared\ProxyComm. The CWAM librarian will promptly provide ISS the final instructions as how to vote the proxy. The Librarian will also periodically check to make sure analysts have filed the relevant documentation.

• ISS shall have procedures in place to ensure that a vote is cast on every security holding maintained by the funds on which a vote is solicited unless otherwise directed by the analyst. On a yearly basis (or when requested), CWAM shall receive a report from ISS detailing CWAM’s voting for the previous period on behalf of the funds.

For All Other Accounts For Which CWAM Has Voting Authority

• CWAM shall use the respective custodian for the account it advises to vote proxies. CWAM shall separately maintain voting records for these accounts.

• The CWAM librarian will be responsible for obtaining all proxy materials from the custodian, forward these to the appropriate CWAM analyst who will review and complete the proxy ballot and return to the librarian or will refer one or more proposals to the Proxy Committee. The analyst will keep documentation (usually copies of email correspondence) of any proposals brought before the Proxy Committee and will instruct the CWAM librarian to vote the proposal in accordance with the Proxy Committee decision. The analyst will file Proxy Committee documentation under G:\Shared\ProxyComm. The CWAM librarian will promptly provide ISS the final instructions as how to vote the proxy. The Librarian will also periodically check to make sure analysts have filed the relevant documentation.

• The CWAM librarian will be responsible for recording all voting records onto a spreadsheet, which will comprise the detail of how CWAM voted each proxy on behalf of the respective client. This spreadsheet shall comply with the appropriate record keeping requirements of the applicable rules and will be available to clients upon request.

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Delegation of Proxy Voting to an Independent Third Party

From time to time, CWAM may face regulatory or compliance limits on the types or amounts of voting securities that it may purchase or hold for client accounts. Among other limits, federal, state, foreign regulatory restrictions, or company-specific ownership limits may restrict the total percentage of an issuer’s voting securities that CWAM can hold for clients (collectively, “Ownership Limits”).

The regulations or company-specific documents governing a number of these Ownership Limits Often focus upon holdings in voting securities. As a result, in limited circumstances in order to comply with such Ownership Limits and/or internal policies designed to comply with such limits, CWAM may delegate proxy voting in certain issuers to ISS, as a qualified, independent third party.

V.    ANNUAL REPORT

CWAM shall submit an annual report to the Chief Compliance Officer of the Funds for his distribution to the Board of Directors of the Columbia Acorn Trust and Wanger Advisors Trust addressing the following:

1. A summary of the Funds’ voting history for the period;

2. Votes cast contrary to the guidelines of this Policy;

3. Votes cast in opposition to management recommendations;

4. Votes cast in conformity with and in opposition to ISS recommendations;

5. Votes that involved potential conflict of interests;

6. The circumstances surrounding all voting abstentions, no votes and missed votes;

7. An assessment of the quality of service provided by ISS, as well as the reasonableness of its fees;

8. Significant matters considered by CWAM’s Proxy Committee; and

9. Recommendations for changes to this Policy.

The annual report should be submitted as soon as practicable after the close of the proxy voting season which normally concludes in June.

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APPENDIX C — INFORMATION REGARDING PENDING AND SETTLED LEGAL PROCEEDINGS

In December 2005, without admitting or denying the allegations, American Express Financial Corporation (AEFC, which is now known as Ameriprise Financial, Inc. (Ameriprise Financial)), entered into settlement agreements with the Securities and Exchange Commission (SEC) and Minnesota Department of Commerce (MDOC) related to market timing activities. As a result, AEFC was censured and ordered to cease and desist from committing or causing any violations of certain provisions of the Investment Advisers Act of 1940, the Investment Company Act of 1940, and various Minnesota laws. AEFC agreed to pay disgorgement of $10 million and civil money penalties of $7 million. AEFC also agreed to retain an independent distribution consultant to assist in developing a plan for distribution of all disgorgement and civil penalties ordered by the SEC in accordance with various undertakings detailed at http://www.sec.gov/litigation/admin/ia-2451.pdf. Ameriprise Financial and its affiliates have cooperated with the SEC and the MDOC in these legal proceedings, and have made regular reports to the funds’ Board of Directors/Trustees.

Ameriprise Financial and certain of its affiliates have historically been involved in a number of legal, arbitration and regulatory proceedings, including routine litigation, class actions, and governmental actions, concerning matters arising in connection with the conduct of their business activities. Ameriprise Financial believes that the Funds are not currently the subject of, and that neither Ameriprise Financial nor any of its affiliates are the subject of, any pending legal, arbitration or regulatory proceedings that are likely to have a material adverse effect on the Funds or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Funds. Ameriprise Financial is required to make 10-Q, 10-K and, as necessary, 8-K filings with the Securities and Exchange Commission on legal and regulatory matters that relate to Ameriprise Financial and its affiliates. Copies of these filings may be obtained by accessing the SEC website at www.sec.gov.

There can be no assurance that these matters, or the adverse publicity associated with them, will not result in increased fund redemptions, reduced sale of fund shares or other adverse consequences to the Funds. Further, although we believe proceedings are not likely to have a material adverse effect on the Funds or the ability of Ameriprise Financial or its affiliates to perform under their contracts with the Funds, these proceedings are subject to uncertainties and, as such, we are unable to estimate the possible loss or range of loss that may result. An adverse outcome in one or more of these proceedings could result in adverse judgments, settlements, fines, penalties or other relief that could have a material adverse effect on the consolidated financial condition or results of operations of Ameriprise Financial.

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APPENDIX S — MORE INFORMATION ABOUT CHOOSING A SHARE CLASS

Class A shares are offered at public offering price per share, which is NAV minus any front-end sales charge that applies. Class A shares may also be subject to a 1.00% CDSC upon redemption. Class C shares are offered at NAV and are subject to a 1.00% CDSC on redemptions within one year after purchase. The CDSCs are described in the Funds’ prospectuses. Class I and Class Z shares are offered at NAV and are not subject to a CDSC. See the Funds’ prospectuses for additional information about the various share classes offered by the Funds.

Front-End Sales Charge Reductions — Accounts Eligible for Aggregation

The following accounts are eligible for account value aggregation for purposes of the right of accumulation and letters of intent as described in the prospectuses offering Class A shares of the Funds:

• Individual or joint accounts;

• Roth and traditional Individual Retirement Accounts (IRAs), Simplified Employee Pension accounts (SEPs), Savings Investment Match Plans for Employees of Small Employers accounts (SIMPLEs) and Tax Sheltered Custodial Accounts (TSCAs);

• Uniform Gifts to Minors Act (UGMA)/Uniform Transfers to Minors (UTMA) accounts for which you, your spouse, or your domestic partner is parent or guardian of the minor child;

• Revocable trust accounts for which you or an immediate family member, individually, is the beneficial owner/grantor;

• Accounts held in the name of your, your spouse’s, or your domestic partner’s sole proprietorship or single owner limited liability company or S corporation;

• Qualified retirement plan assets, provided that you are the sole owner of the business sponsoring the plan, are the sole participant (other than a spouse) in the plan, and have no intention of adding participants to the plan; and

• Investments in wrap accounts;

provided that each of the accounts identified above is invested in Class A, Class B, Class C, Class E, Class F, Class T, Class W and/or Class Z shares of the Funds.

The following accounts are not eligible for account value aggregation:

• Accounts of pension and retirement plans with multiple participants, such as 401(k) plans (which are combined to reduce the sales charge for the entire pension or retirement plan and therefore are not used to reduce the sales charge for your individual accounts);

• Accounts invested in Class I, Class R, Class R3, Class R4, Class R5 and/or Class Y shares of the Funds;

• Investments in 529 plans, donor advised funds, variable annuities, variable life insurance products, or managed separate accounts;

• Charitable and irrevocable trust accounts; and

• Accounts holding shares of money market Funds that used the Columbia brand before May 1, 2010.

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Sales Charge Waivers

Front-End Sales Charge Waivers (Class A Shares)

The following categories of investors may buy Class A shares at net asset value, without payment of any front-end sales charge that would otherwise apply:

• Current or retired directors or trustees of the Columbia Funds, and officers or employees of Columbia Management or its affiliates, including the Investment Manager;¹

• Current or retired Ameriprise Financial Services, Inc. financial advisors and employees of such financial advisors;¹

• Registered representatives and other employees of affiliated or unaffiliated selling agents having a selling agreement with the Distributor;¹

• Registered broker-dealer firms that have entered into a dealer agreement with the Distributor may buy Class A shares without paying a front-end sales charge for their investment account only;

• Portfolio managers employed by any subadviser of the Columbia Funds;¹

• Partners and employees of outside legal counsel to the Columbia Funds or the Columbia Funds’ directors trustees who regularly provide advice and services to the Columbia Funds, or to their directors or trustees;

• Direct rollovers from qualified employee benefit plans, provided that the rollover involves a transfer to Class A shares in the same Fund or Columbia Fund;

• Employees of Bank of America, its affiliates and subsidiaries;

• Employees or partners of Marsico Capital Management, LLC (or its successors);

• Individuals receiving a distribution from a Bank of America trust, fiduciary, custodial or other similar account may use the proceeds of that distribution to buy Class A shares without paying a front-end sales charge, as long as the proceeds are invested in the funds within 90 days of the date of distribution;

• Any shareholder who owned shares of any fund of Columbia Acorn Trust (formerly named Liberty Acorn Trust) on September 29, 2000 (when all of the then outstanding shares of Columbia Acorn Trust were re-designated Class Z shares) and who since that time has remained a shareholder of any Columbia Fund, may buy Class A shares of any Columbia Fund without paying a front-end sales charge in those cases where a Columbia Fund Class Z share is not available;

• Galaxy Fund shareholders prior to December 1, 1995; and shareholders who (i) bought Galaxy Fund Prime A shares without paying a front-end sales charge and received Class A shares in exchange for those shares during the Galaxy/Liberty Fund reorganization; and (ii) continue to maintain the account in which the Prime A shares were originally bought;

• Separate accounts established and maintained by an insurance company which are exempt from registration under Section 3(c)(11); and

• At a Columbia Fund’s discretion, front-end sales charges may be waived for shares issued in plans of reorganization, such as mergers, asset acquisitions and exchange offers, to which the Columbia Fund is a party.

¹  Including their spouses or domestic partners, children or step-children, parents, step-parents or legal guardians, and their spouse’s or domestic partner’s parents, step-parents, or legal guardians.

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• Purchases made:

• With dividend or capital gain distributions from a Columbia Fund or from the same class of another Columbia Fund;

• Through or under a wrap fee product or other investment product sponsored by a selling agent that charges an account management fee or other managed agency/asset allocation accounts or programs involving fee-based compensation arrangements that have or that clear trades through a selling agent that has a selling agreement with the Distributor;

• Through state sponsored college savings plans established under Section 529 of the Internal Revenue Code; or

• Through banks, trust companies and thrift institutions, acting as fiduciaries.

• Through “employee benefit plans” created under section 401(a), 401(k), 457 and 403(b), and qualified deferred compensation plans, that have a plan level or omnibus account maintained with a Columbia Fund or the Transfer Agent and transacts directly with the Columbia Fund or the Transfer Agent through a third party administrator or third party recordkeeper.

Investors can also buy Class A shares without paying a sales charge if the purchase is made from the proceeds of a sale from Columbia Fund Class A, B, C or T shares (other than Columbia Money Market Fund or Columbia Government Money Market Fund) within 90 days, up to the amount of the sales proceeds. In addition, shareholders of the money market fund series of BofA Funds Series Trust, which were formerly referred to as the Columbia Money Market Funds (the Former Columbia Money Market Funds), can also buy Class A shares of the Columbia Funds without paying a sales charge if the purchase is made from the proceeds of a sale of shares from a Former Columbia Money Market Fund within 90 days, up to the amount of the sales proceeds, provided that the proceeds are from the sale of shares of a Former Columbia Money Market Fund purchased on or before April 30, 2010. To be eligible for these reinstatement privileges the purchase must be made into an account for the same owner, but does not need to be into the same Columbia Fund from which the shares were sold. The Transfer Agent, Distributor or their agents must receive a written reinstatement request within 90 days after the shares are sold and the purchase of Class A shares through this reinstatement privilege will be made at the NAV of such shares next calculated after the request is received in good order.

Restrictions may apply to certain accounts and certain transactions. The Funds may change or cancel these terms at any time. Any change or cancellation applies only to future purchases. Unless you provide your financial advisor with information in writing about all of the factors that may count toward a waiver of the sales charge, there can be no assurance that you will receive all of the waivers for which you may be eligible. You should request that your financial advisor provide this information to the Funds when placing your purchase order. For more information about the sales charge reductions and waivers described here, as well as additional categories of eligible investors, please see the applicable prospectus.

Contingent Deferred Sales Charges (Class A, Class B and Class C Shares)

Shareholders won’t pay a CDSC upon redemption of Class A and Class C shares:

• In the event of the shareholder’s death;

• For which no sales commission or transaction fee was paid to an authorized selling agent at the time of purchase;

• Purchased through reinvestment of dividend and capital gain distributions;

• In an account that has been closed because it falls below the minimum account balance;

• That result from required minimum distributions taken from retirement accounts upon the shareholder’s attainment of age 70 ¹/₂.

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• That result from returns of excess contributions made to retirement plans or individual retirement accounts, so long as the selling agent returns the applicable portion of any commission paid by the Distributor;

• Of Class A shares of a Fund initially purchased by an employee benefit plan;

• Of Class C shares of a Fund initially purchased by an employee benefit plan that are not connected with a plan level termination; and

• At a Columbia Fund’s discretion, issued in connection with plans of reorganization, including but not limited to mergers, asset acquisitions and exchange offers, to which the Columbia Fund is a party.

Shareholders won’t pay a CDSC upon redemption of Class B shares:

• In the event of the shareholder’s death; and

• That result from required minimum distributions taken from retirement accounts upon the shareholder’s attainment of age 70 ¹/₂.

Shareholders won’t pay a CDSC upon redemptions of Class A, Class B or Class C shares:

• after the sole shareholder on an individual account or a joint tenant on a joint tenant account becomes disabled (as defined by Section 72(m)(7) of the Code). To be eligible for such a waiver: (i) the disability must arise after the account is opened and (ii) a letter from a physician must be signed under penalty of perjury stating the nature of the disability. If the account is transferred to a new registration and then shares are sold, the applicable CDSC will be charged.*

• by health savings accounts sponsored by third party platforms, including those sponsored by Bank of America affiliates (for shares purchased prior to September 7, 2010).*

• made to cover medical payments that exceed 7.5% of income.*

• made to pay for medical insurance by an individual who has separated from employment and who has received unemployment compensation under a federal or state program for at least twelve weeks.*

• occurring pursuant to a Systematic Withdrawal Plan (SWP) established with the Transfer Agent, to the extent that the sales do not exceed, on an annual basis, 12% of the account’s value as long as distributions are reinvested (for shares purchased prior to September 7, 2010). Otherwise, a CDSC will be charged on SWP sales until this requirement is met.

• by certain group retirement plans held in omnibus accounts (except for Class B shares). CDSCs may be waived on redemptions of Class A shares initially purchased by an employee benefit plan. However, CDSC may not be waived for Class C shares if the waiver would occur as a result of a plan-level termination.

• in connection with distributions from qualified retirement plans, government (Section 457) plans, individual retirement accounts or custodial accounts under Section 403(b)(7) of the Code following normal retirement or the attainment of age 59 ¹/₂ (for shares purchased prior to September 7, 2010).**

• in connection with loans from qualified retirement plans to shareholders (for all Class B shares and for Class A and Class C shares purchased prior to September 7, 2010).*

* Shareholders and selling agents must inform the Fund or the Transfer Agent in writing that the shareholder qualifies for the particular sales charge waiver and provide proof thereof.

** For direct trades on non-prototype retirement accounts where the date of birth of the shareholder is not maintained, the shareholder or selling agent must inform the Fund or the Transfer Agent in writing that the shareholders qualifies for the particular sales charge waiver and provide proof thereof.

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Restrictions may apply to certain accounts and certain transactions. The Distributor may, in its sole discretion, authorize the waiver of the CDSC for additional classes of investors. The Funds may change or cancel these terms at any time. Any change or cancellation applies only to future purchases. For more information about the sales charge reductions and waivers described here, as well as additional categories of eligible redemptions, see the Funds’ prospectuses.

Minimum Initial Investment in Class Z Shares

Class Z shares are available only to certain eligible investors, which are subject to different minimum initial investment requirements described in the Funds’ prospectuses for Class Z shares. In addition to the categories of Class Z investors described in the prospectuses, the minimum initial investments in Class Z shares are as follows:

• There is no minimum initial investment in Class Z shares for any health savings account sponsored by a third party platform, including those sponsored by affiliates of Bank of America.

• The minimum initial investment in Class Z shares for the following categories of eligible investors is $2,000:

• Any client of Bank of America or one of its subsidiaries buying shares through an asset management company, trust, fiduciary, retirement plan administration or similar arrangement with Bank of America or the subsidiary.

• Any employee (or family member of an employee) of Bank of America or one of its subsidiaries.

• Any investor buying shares through a Columbia Management state tuition plan organized under Section 529 of the Internal Revenue Code.

• Any trustee or director (or family member of a trustee or director) of a fund distributed by the Distributor.

Class B Shares — Conversion to Class A Shares

In general, the Funds’ Class B shares convert to Class A shares after eight years. The following rules apply to the conversion of Class B shares to Class A shares:

• Class B shares are converted on or about the 15th day of the month that they become eligible for conversion. For purposes of determining the month when your Class B shares are eligible for conversion, the start of the holding period is the first day of the month in which your purchase was made.

• Any shares you received from reinvested distributions on these shares generally will convert to Class A shares at the same time.

• You’ll receive the same dollar value of Class A shares as the Class B shares that were converted. Class B shares that you received from an exchange of Class B shares of another Fund will convert based on the day you bought the original shares.

• No sales charge or other charges apply, and conversions are free from U.S. federal income tax.

Additional Information About Class R Eligibility

Class R shares are available only to eligible health savings accounts sponsored by third party platforms, including those sponsored by Ameriprise Financial affiliates, eligible retirement plans and, at the discretion of the Distributor, other types of retirement accounts held through platforms maintained by selling agents approved by the Distributor. Eligible retirement plans include any retirement plan other than individual 403(b) plans. Class R shares are generally not available for investment through retail nonretirement accounts, traditional and Roth

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IRAs, Coverdell Education Savings Accounts, SEPs, SAR-SEPs, Simple IRAs or 529 tuition programs. Contact the Transfer Agent or your retirement plan or health savings account administrator for more information about investing in Class R shares.

Additional Information About Class R4 Eligibility

Class R4 shares are available only to (i) omnibus retirement plans, (ii) trust companies or similar institutions, (iii) broker-dealers, banks, trust companies and similar institutions that clear Fund share transactions for their client or customer investment advisory or similar accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R4 eligibility apart from selling, servicing or similar agreements, (iv) 501(c)(3) charitable organizations, (v) 529 plans and (vi) health savings accounts.

Additional Information About Class Z Closing

Omnibus retirement plans that opened and, subject to certain exceptions, funded a Class Z account with a Fund as of the close of business on March 28, 2013, and continuously hold Class Z shares in such account after March 28, 2013, may generally continue to make additional purchases of Class Z shares, open new Class Z accounts and add new participants. The Distributor may, in its sole discretion, delay the funding requirement described above to allow an omnibus retirement plan that opened a Class Z account (the initial Class Z account) with a Fund as of the close of business on March 28, 2013 to make additional purchases of Class Z shares, open new Class Z accounts and add new participants after March 28, 2013 so long as the initial Class Z account is funded by July 2, 2013.

New Minimum Initial Investment Amount for Class R5

A minimum initial investment of $100,000 applies to purchases of Class R5 shares of a Fund for accounts of any registered investment adviser that clears Fund share transactions for their client or customer accounts through designated selling agents and their mutual fund trading platforms that have been granted specific written authorization from the Transfer Agent with respect to Class R5 eligibility apart from selling, servicing or similar agreements. There is no minimum initial investment in Class R5 shares for omnibus retirement plans.

Additional Eligible Investors

The Distributor, in its sole discretion, may accept investments in any share class of a Fund from investors other than those listed above and in the Fund’s prospectus(es).

Additional Information About Minimum Initial Investments

The Distributor, in its sole discretion, may also waive minimum initial investment requirements, including without limitation the requirement for omnibus retirement plans with plan assets of less than $10 million to invest $500,000 or more in Class Y shares of a Fund. Minimum investment and related requirements may be modified at any time, with or without prior notice.

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PART C OTHER INFORMATION

Item 28.	Exhibits:
Note:	As used herein, the term “Post-effective Amendment” refers to a post-effective amendment to the registration statement of Registrant or its predecessor, The Acorn Fund, Inc., under the Securities Act of 1933 on form S-5, N-1 or N-1A, no. 2-34223.
a.1	Agreement and Declaration of Trust. (1)
a.2	Amendment No. 1 to Agreement and Declaration of Trust. (3)
a.3	Amendment No. 2 to Agreement and Declaration of Trust. (4)
b.	Bylaws dated September 28, 2004, as amended through December 17, 2009. (8)
c.	None.
d.1	Organizational Expenses Agreement between Acorn Investment Trust (now known as Columbia Acorn Trust) and Wanger Asset Management, L.P. (now known as Columbia Wanger Asset Management, LLC), dated September 3, 1996. (2)
d.2	Organizational and Offering Costs Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC (relating to Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund) dated August 17, 2011. (9)
d.3	Investment Advisory Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC dated May 27, 2010, Schedules A and B last amended June 8, 2011. (9)
d.4	Administrative Services Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC dated May 1, 2010, Schedule A last amended June 8, 2011. (9)
e.1	Distribution Agreement between Columbia Acorn Trust and Columbia Management Investment Distributors, Inc. dated May 1, 2010, Schedules I and II last amended June 8, 2011. (9)
e.2	Amendment dated April 12, 2011 to the Distribution Agreement between Columbia Acorn Trust and Columbia Management Investment Distributors, Inc. dated May 1, 2010. (9)
f.	None.
g.	Custody Agreement among JPMorgan Chase Bank, N.A., Columbia Acorn Trust and Wanger Advisors Trust dated December 15, 2010, effective July 22, 2011, with Addendums dated July 14, 2011. (9)

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h.1	Amended and Restated Transfer, Dividend Disbursing and Shareholders’ Servicing Agent Agreement between Columbia Acorn Trust and Columbia Management Investment Services Corp. dated May 1, 2012. (10)
h.2	Compliance Agreement between Columbia Acorn Trust and Ameriprise Financial, Inc. dated May 1, 2010. (7)
h.3	Fee Waiver Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC (relating to Class A, Class B, Class C and Class Z shares of Columbia Thermostat Fund) dated April 27, 2012. (10)
h.4	Fee Waiver and Expense Reimbursement Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC (relating to Class R4, Class R5 and Class Y shares of Columbia Thermostat Fund) dated November 8, 2012.
h.5	Amended and Restated Fee Waiver and Expense Reimbursement Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC (relating to Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund) dated November 8, 2012.
h.6	Participation Agreement among Merrill Lynch Life Insurance Company, Columbia Acorn Trust and Columbia Funds Distributor, Inc. (now named Columbia Management Distributors, Inc.) dated March 4, 2005. (5)
h.7	Amendment No. 1 to Participation Agreement among Merrill Lynch Life Insurance Company, Columbia Acorn Trust and Columbia Management Distributors, Inc. (formerly Columbia Funds Distributor, Inc.) dated March 30, 2007. (6)
h.8	Participation Agreement among ML Life Insurance Company of New York, Columbia Acorn Trust and Columbia Funds Distributor, Inc. (now named Columbia Management Distributors, Inc.) dated March 4, 2005. (5)
h.9	Amendment No. 1 to Participation Agreement among ML Life Insurance Company of New York, Columbia Acorn Trust and Columbia Management Distributors, Inc. (formerly Columbia Funds Distributor, Inc.) dated March 30, 2007. (6)
i.	Opinion letter and written consent of Perkins Coie LLP relating to the series of Columbia Acorn Trust.
j.	Consent of independent registered accounting firm.
k.	None.
l.	None.
m.1	Plan of Distribution Pursuant to Rule 12b-1 last approved by the Board of Trustees June 8, 2011. (9)
m.2	Rule 12b-1 Plan Implementing Agreement last approved by the Board of Trustees March 2, 2011. (9)
n.1	Amended and Restated Plan Pursuant to Rule 18f-3(d) effective November 8, 2012, last approved by the Board of Trustees September 19, 2012.
o.	None.
p.1	Code of Ethics for Columbia Wanger Asset Management, LLC, Columbia Acorn Trust and Wanger Advisors Trust, as amended through August 23, 2011. (10)

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p.2	Code of Ethics for Non-Management Trustees, as amended, effective as of September 19, 2012.
p.3	Code of Ethics for Columbia Management Investment Distributors, Inc., the principal underwriter of the Funds, effective July 1, 2011. (10)

(1) Previously filed. Incorporated by reference to post-effective amendment No. 53 to the Registrant’s registration statement on form N-lA, Securities Act registration number 2-34223 (the “Registration Statement”), filed on April 30, 1996.

(2) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 61 to the Registration Statement filed on April 30, 1998.

(3) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 70 to the Registration Statement filed on May 1, 2001.

(4) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 77 to the Registration Statement filed on March 1, 2005.

(5) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 79 to the Registration Statement filed on April 28, 2006.

(6) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 80 to the Registration Statement filed on April 30, 2007.

(7) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 87 to the Registration Statement filed on September 27, 2010.

(8) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 88 to the Registration Statement filed on April 29, 2011.

(9) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 91 to the Registration Statement filed on August 17, 2011.

(10) Previously filed. Incorporated by reference to Registrant’s post-effective amendment No. 93 to the Registration Statement filed on April 27, 2012.

Item 29. Persons Controlled By or Under Common Control with Registrant

The Registrant does not consider that there are any persons directly or indirectly controlled by, or under common control with, the Registrant within the meaning of this item. The information in the prospectuses under the caption “Management of the Fund - Primary Service Providers - The Adviser” and in the statement of additional information under the caption “The Adviser and Investment Advisory Services” is incorporated by reference.

Item 30. Indemnification

Article VIII of the Agreement and Declaration of Trust of the Registrant (listed as exhibit a.1 and incorporated in this filing by reference) provides in effect that Registrant shall provide certain indemnification of its trustees and officers. In accordance with Section 17(h) of the Investment Company Act of 1940, as amended, that provision shall not protect any person against any liability to the Registrant or its shareholders to which he would otherwise be subject by reason of willful misfeasance, bad faith, gross negligence or reckless disregard of the duties involved in the conduct of his office.

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Insofar as indemnification for liabilities arising under the Securities Act of 1933, as amended (the “Securities Act”) may be permitted to trustees, officers and controlling persons of the Registrant pursuant to the foregoing provisions, or otherwise, the Registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the Registrant of expenses incurred or paid by a trustee, officer or controlling person of the Registrant in the successful defense of any action, suit or proceeding) is asserted by such trustee, officer or controlling person in connection with the securities being registered, the Registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

The Trust has entered into Indemnification Agreements with each of the independent trustees which provide that the Trust shall indemnify and advance expenses to the independent trustees as provided in the Indemnification Agreements and otherwise to the fullest extent permitted by applicable law. The Trust will indemnify the independent trustees from and against any and all judgments, penalties, fines and amounts paid in settlement, and all expenses actually and reasonably incurred by the independent trustees in connection with a proceeding to which he or she is a party to by reason of his or her position as an independent trustee. The Trust will not indemnify the independent trustees for monetary settlements or judgments relating to insider trading, disgorgements of profits pursuant to Section 16(b) of the Securities Exchange Act of 1934, or any liability to the Trust or its shareholders with respect to a final adjudication that an action or omission by an independent trustee was committed in bad faith, involved deliberate dishonesty or that the trustee engaged in willful misfeasance, bad faith, gross negligence or reckless disregard of his or her duties.

The Registrant, its trustees and officers, its investment adviser and persons affiliated with them are insured under policies of insurance maintained by Registrant and its investment adviser, respectively, within the limits and subject to the limitations of the policies, against certain expenses in connection with the defense of actions, suits or proceedings, and certain liabilities that might be imposed as a result of such actions, suits or proceedings, to which they are parties by reason of being or having been such trustees or officers. The policies expressly excludes coverage for any trustee or officer whose personal dishonesty, fraudulent breach of trust, lack of good faith, or intention to deceive or defraud has been finally adjudicated or may be established or who willfully fails to act prudently.

Item 31. Business and Other Connections of Investment Adviser

The information in the prospectuses under the caption “Management of the Fund - Primary Service Providers - The Adviser” is incorporated by reference. Columbia Wanger Asset Management, LLC (“CWAM”) was not at any time during the past two years engaged in any other business, profession, vocation or employment of a substantial nature either for its own account or in the capacity of director, officer, employee, partner or trustee. Nor was the general partner of CWAM so engaged during the two years prior to May 1, 2010 during which CWAM operated as a limited partnership.

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Item 32. Principal Underwriters

(a) Columbia Management Investment Distributors, Inc. (“CMID”), an affiliate of Columbia Management Investment Advisers, LLC, is the Registrant’s principal underwriter. CMID also acts in such capacity for each series of Columbia Funds Variable Insurance Trust, Columbia Funds Series Trust, Columbia Funds Series Trust I, Columbia Funds Variable Insurance Trust I, and Wanger Advisors Trust and certain other open-end investment companies in the Columbia Family of Funds (the mutual fund complex that is comprised of the open-end investment companies advised by the Adviser or its affiliates and principally underwritten by CMID). CMID acts as placement agent for Columbia Funds Master Investment Trust, LLC.

(b) The tables below lists each director or officer of the principal underwriter named in the answer to Item 25.

BOARD OF DIRECTORS

William F. “Ted” Truscott (Chairman)

Amy Unckless

Jeffrey F. Peters

Christopher Thompson

OFFICERS

William F. “Ted” Truscott	Chief Executive Officer
Amy Unckless	President and Chief Administrative Officer
Jeffrey F. Peters	Senior Vice President
Dave K. Stewart	Chief Financial Officer
Scott R. Plummer	Senior Vice President, Chief Counsel and Assistant Secretary
Stephen O. Buff	Vice President, Chief Compliance Officer
Christopher Thompson	Senior Vice President and Head of Investment Products and Marketing
Hector DeMarchena	Vice President – Institutional Asset Management Product
	Administration and Assistant Treasurer
Mark Dence	Vice President – National Sales Manager IO
Joe Feloney	Vice President – National Sales Manager –
	US Trust/Private Wealth Management
Leslie Moon	Vice President – Mutual Fund Technology
Brian Walsh	Vice President, Strategic Relations
Frank Kimball	Vice President, Asset Management Distribution Operations and Governance
Thomas R. Moore	Secretary
Michael E. DeFao	Vice President and Assistant Secretary
Paul Goucher	Vice President and Assistant Secretary
Tara Tilbury	Vice President and Assistant Secretary
Nancy W. LeDonne	Vice President and Assistant Secretary
Ryan C. Larrenaga	Vice President and Assistant Secretary
Joseph L. D’Alessandro	Vice President and Assistant Secretary
Christopher O. Petersen	Vice President and Assistant Secretary
Eric T. Brandt	Vice President and Assistant Secretary
Maureen T. Andrews	Assistant Secretary
Jon V. Boeck	Assistant Secretary
Melanie Beckman	Assistant Secretary
Jennifer B. Hoese	Assistant Secretary
Christopher R. Kinney	Assistant Secretary
Donna Lindgren	Assistant Secretary
Sherri Mullen	Assistant Secretary
Daniel P. Olson	Assistant Secretary
Alanna Proctor	Assistant Secretary
Erik Saarinen	Assistant Secretary
Sharon Hahn	Assistant Secretary
Heather Heald	Assistant Secretary
Geralyn Kephart-Strong	Assistant Secretary
Marc Wilson	Assistant Secretary
Dawn M. Robinson	Assistant Secretary
Diana L. Roberts	Assistant Secretary
Peggy I. Say	Assistant Secretary
Michael Shuckerow	Assistant Secretary
Robin Smith	Assistant Secretary
Steve Welsh	Assistant Secretary
James L. Hamalainen	Treasurer
Kathryn Bealka	Assistant Treasurer
John J. Hirsch	Assistant Treasurer
Michael H. Gilmore	Assistant Treasurer
Mike Pelzel	Assistant Treasurer
Steve Twait	Assistant Treasurer
Lani J. Canniff	Assistant Treasurer
Rochelle Lockwood	Assistant Treasurer
Amy Angel	Assistant Treasurer
Debra R. Dahl	Assistant Treasurer
Chris Gies	Assistant Treasurer
Simon McKay	Assistant Treasurer
Daniel J. Murtha	Assistant Treasurer
Scott W. Peterson	Assistant Treasurer
Cathy Donovan	Assistant Treasurer
Mark Matuga	Assistant Treasurer
Mary A. McKeen	Assistant Treasurer
Jay Rasula	Assistant Treasurer
Bruce F. Shankey	Assistant Treasurer
Jim Nygren	Assistant Treasurer
Richard C. Dluzniewski	Assistant Treasurer
Joyce M. Ford	Assistant Treasurer
Tara Dziengel	Interim Anti-Money Laundering Officer and
	Identify Theft Prevention Officer
Kevin Wasp	Ombudsman
Lee Faria	Conflicts Officer

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Item 33. Location of Accounts and Records

Bruce H. Lauer, Vice President, Secretary and Treasurer

Columbia Acorn Trust

227 West Monroe Street, Suite 3000

Chicago, Illinois 60606

Certain records, including records relating to the Registrant’s shareholders and the physical possession of its securities, may be maintained at the main office of Registrant’s transfer agent, Columbia Management Investment Services Corp., located at 225 Franklin Street, Boston Massachusetts 02110 or custodian, JPMorgan Chase Bank, N.A., One Chase Manhattan Plaza, New York, New York 10005.

Item 34. Management Services

Not applicable.

Item 35. Undertakings

Not applicable.

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all the requirements for effectiveness of this post-effective amendment pursuant to Rule 485(b) under the Securities Act of 1933 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Chicago and State of Illinois on November 7, 2012.

COLUMBIA ACORN TRUST
By	/S/    CHARLES P. MCQUAID
	Charles P. McQuaid, President

Pursuant to the requirements of the Securities Act of 1933, this amendment to the registration statement has been signed below by the following persons in the capacities and on the dates indicated.

Name	Title		Date
/S/    LAURA M. BORN	Trustee and Chair	)
Laura M. Born		)
		)
/S/    MICHELLE L. COLLINS	Trustee	)
Michelle L. Collins		)
		)
/S/    MAUREEN M. CULHANE	Trustee	)
Maureen M. Culhane		)
		)
/S/    MARGARET M. EISEN	Trustee	)
Margaret M. Eisen		)
		)
/S/    JOHN C. HEATON	Trustee	)
John C. Heaton		)
		)
/S/    STEVEN N. KAPLAN	Trustee	)
Steven N. Kaplan		)
		)
/S/    DAVID J. RUDIS	Trustee	)	November 7, 2012
David J. Rudis		)
		)
/S/    DAVID B. SMALL	Trustee	)
David B. Small		)
		)
/S/    CHARLES P. MCQUAID	Trustee and President (principal executive	)
Charles P. McQuaid	officer)	)
		)
/S/    BRUCE H. LAUER	Treasurer (principal financial and	)
Bruce H. Lauer	accounting officer)	)

Index of Exhibits Filed with this Amendment

Exhibit Number	Exhibit
h.4	Fee Waiver and Expense Reimbursement Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC (relating to Class R4, Class R5 and Class Y shares of Columbia Thermostat Fund) dated November 8, 2012.
h.5	Amended and Restated Fee Waiver and Expense Reimbursement Agreement between Columbia Acorn Trust and Columbia Wanger Asset Management, LLC (relating to Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund) dated November 8, 2012.
i.	Opinion letter and written consent of Perkins Coie LLP relating to the series of Columbia Acorn Trust.
j.	Consent of independent registered accounting firm.
n.1	Amended and Restated Plan Pursuant to Rule 18f-3(d) effective November 8, 2012, last approved by the Board of Trustees September 19, 2012.
p.2	Code of Ethics for Non-Management Trustees, as amended, effective as of September 19, 2012.

EX-99.(H)(4)

EX.h.4

COLUMBIA WANGER ASSET MANAGEMENT, LLC

227 West Monroe, Suite 3000

Chicago, IL 60606

November 8, 2012

Columbia Acorn Trust

227 West Monroe Street, Suite 3300

Chicago, Illinois 60606

Ladies and Gentlemen:

Columbia Wanger Asset Management, LLC (“CWAM”) hereby contractually undertakes as of the date hereof as follows with respect to the series of Columbia Acorn Trust designated Columbia Thermostat Fund (the “Fund”):

CWAM will waive fees and reimburse certain expenses of the Fund, such that total Fund ordinary operating expenses (excluding interest and fees on borrowings, and expenses associated with the Fund’s investment in other investment companies) do not exceed, through November 8, 2013, the annual rates of:

• 0.25% of the Fund’s average daily net assets attributable to Class R4 shares;

• 0.27% of the Fund’s average daily net assets attributable to Class R5 shares; and

• 0.22% of the Fund’s average daily net assets attributable to Class Y shares.

This undertaking is in addition to any undertaking with respect to other share classes of the Fund and shall be binding upon any successors and assignees of CWAM.

Very truly yours,

COLUMBIA WANGER ASSET MANAGEMENT, LLC

By:	/s/ Bruce H. Lauer
Bruce H. Lauer
Chief Operating Officer

EX.h.4

Agreed and accepted by

COLUMBIA ACORN TRUST,

On behalf of its series Columbia Thermostat Fund

By:	/s/ Bruce H. Lauer
Bruce H. Lauer
Vice President, Secretary and Treasurer

EX-99.(H)(5)

EX.h.5

AMENDED AND RESTATED

FEE WAIVER AND EXPENSE REIMBURSEMENT AGREEMENT

THIS AGREEMENT, dated as of November 8, 2012, is by and between Columbia Acorn Trust (the “Trust”), a Massachusetts business trust registered as an open-end diversified management investment company under the Investment Company Act of 1940, as amended, on behalf of its series Columbia Acorn European Fund and Columbia Acorn Emerging Markets Fund (each a “Fund” and together, the “Funds”), and Columbia Wanger Asset Management, LLC, a Delaware limited liability company registered as an investment adviser under the Investment Advisers Act of 1940, as amended (the “Adviser”), and amends and restates the Fee Waiver and Expense Reimbursement Agreement, dated as of August 17, 2011, between the Trust, on behalf of each Fund, and the Adviser (the “Original Agreement”).

WHEREAS, the Adviser serves as investment adviser to each of the Funds pursuant to a separate investment advisory agreement between the Trust, on behalf of the Funds, and the Adviser (the “Investment Advisory Agreement”).

NOW, THEREFORE, in consideration of the mutual covenants herein contained and other good and valuable consideration, the receipt whereof is hereby acknowledged, the parties hereto agree as follows:

1. Fee Waivers and Expense Reimbursements.

Columbia Acorn European Fund. The Adviser shall waive fees payable to it under the Investment Advisory Agreement by Columbia Acorn European Fund, and shall reimburse certain expenses of Columbia Acorn European Fund, so that the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rates of:

• 1.75% of the Fund’s average daily net assets attributable to Class A shares;

• 2.50% of the Fund’s average daily net assets attributable to Class C shares;

• 1.31% of the Fund’s average daily net assets attributable to Class I shares;

• 1.36% of the Fund’s average daily net assets attributable to Class R5 shares; and

• 1.50% of the Fund’s average daily net assets attributable to Class Z shares.

Columbia Acorn Emerging Markets Fund. The Adviser shall waive fees payable to it under the Investment Advisory Agreement by Columbia Acorn Emerging Markets Fund, and shall reimburse certain expenses of Columbia Acorn European Fund, so that the Fund’s ordinary operating expenses (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) do not exceed the annual rates of:

• 1.85% of the Fund’s average daily net assets attributable to Class A shares;

• 2.60% of the Fund’s average daily net assets attributable to Class C shares;

• 1.41% of the Fund’s average daily net assets attributable to Class I shares;

• 1.60% of the Fund’s average daily net assets attributable to Class R4 shares;

• 1.46% of the Fund’s average daily net assets attributable to Class R5 shares; and

• 1.60% of the Fund’s average daily net assets attributable to Class Z shares.

EX.h.5

2. Recoupment.

The Adviser shall be entitled to recoup from each Fund any fees waived and/or expenses reimbursed with respect to any share class offered by the Fund for a one-year period following the date of such fee waiver and/or reimbursement if such recovery does not cause the ordinary operating expenses of the Fund (excluding interest and fees on borrowings and expenses associated with the Fund’s investment in other investment companies, if any) to exceed the annual rates set forth in Section 1 of this Agreement, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less.

3. Term and Termination.

The Adviser shall waive fees and reimburse expenses of each Fund, as described herein, through April 30, 2013 for each class of shares other than Class R5 shares of Columbia Acorn European Fund and Class R4 and Class R5 shares of Columbia Acorn Emerging Markets Fund for which the Adviser shall waive fees and expenses, as described herein, through November 8, 2013. This Agreement may be terminated as to a Fund only upon the mutual agreement of the Board of Trustees of the Trust and the Adviser.

4. Entire Agreement; Modification; Amendment.

This Agreement constitutes the entire agreement of the parties with respect to its subject matter and amends and restates the Original Agreement. Each provision herein shall be treated as separate and independent from any other provision or agreement herein and shall be enforceable notwithstanding the enforceability of any such other provision or agreement. In addition, each provision herein shall be treated as separate and independent with respect to each Fund and shall be treated as separate and independent from such provision or agreement with respect to the other Fund. No modification or amendment of this Agreement shall be binding unless it is made in writing and executed by both the Trust, on behalf of the Funds, and the Adviser.

* * * * *

IN WITNESS WHEREOF, the parties hereto have caused this instrument to be executed by their officers designated below as of the day and year first above written.

COLUMBIA ACORN TRUST
on behalf of its series Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund
By:	/s/ Bruce H. Lauer
	Name: Bruce H. Lauer
	Title: Vice President, Secretary and Treasurer
COLUMBIA WANGER ASSET MANAGEMENT, LLC
By:	/s/ Charles P. McQuaid
	Name: Charles P. McQuaid
	Title: President

EX-99.(I)

Ex.i.

Mary C. Moynihan PHONE: (202) 654-6254 FAX:     (202) 654-9697 EMAIL:  MMoynihan@perkinscoie.com

November 7, 2012

Columbia Acorn Trust

227 West Monroe Street, Suite 3000

Chicago, Illinois 60606

Ladies and Gentlemen:

We have acted as counsel to Columbia Acorn Trust, a business trust formed under the laws of the Commonwealth of Massachusetts (the “Trust”), in connection with the filing with the Securities and Exchange Commission (the “SEC”) of Post-Effective Amendment No. 95 to the Trust’s Registration Statement on Form N-1A (File Nos. 002-34223; 811-01829) (the “Post-Effective Amendment”), registering an indefinite number of (i) Class Y shares of beneficial interest of Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International, Columbia Acorn International Select, Columbia Acorn Select and Columbia Thermostat Fund, each a series of the Trust; (ii) Class R4 shares of beneficial interest of Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International, Columbia Acorn International Select, Columbia Acorn Select, Columbia Thermostat Fund and Columbia Emerging Markets Fund, each a series of the Trust; and (iii) Class R5 shares of beneficial interest of Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select, Columbia Thermostat Fund, Columbia European Fund and Columbia Emerging Markets Fund, each a series of the Trust (all such shares, collectively, the “Shares”), under the Securities Act of 1933, as amended (the “1933 Act”).

You have requested our opinion as to the matters set forth below in connection with the filing of the Post-Effective Amendment. For purposes of rendering that opinion, we have examined the Post-Effective Amendment, the Declaration of Trust, as amended, the By-Laws of the Trust, and the actions by the board of trustees of the Trust that provide for the issuance of the Shares, and we have made such other investigation as we have deemed appropriate. We have examined and relied upon certificates of public officials and, as to certain matters of fact that are material to our opinion, we have also relied on a certificate of an officer of the Trust. In rendering our opinion, we also have made the assumptions that are customary in opinion letters of this kind. We have not verified any of those assumptions.

November 7, 2012

Page 2

Based upon and subject to the foregoing, we are of the opinion that:

(1) The Shares being registered pursuant to the Post-Effective Amendment have been duly authorized for issuance by the Trust; and

(2) When issued and paid for at net asset value as contemplated by the Post-Effective Amendment, the Shares will be validly issued, fully paid, and non-assessable. In this regard, however, we note that the Trust is a Massachusetts business trust and, under certain circumstances, shareholders of a Massachusetts business trust could be held personally liable for the obligations of the trust.

Our opinion, as set forth herein, is based on the facts in existence and the laws in effect on the date hereof and is limited to the Federal laws of the United States and the laws of the Commonwealth of Massachusetts. We are members of the Bar of the District of Columbia and our opinion, as it relates to the laws of the Commonwealth of Massachusetts, is based solely on our review of the laws, and, where applicable, published cases, rules or regulations relating thereto, of the Commonwealth of Massachusetts that, in our experience, generally are applicable to the issuance of shares by entities such as the Trust.

This opinion is rendered solely in connection with the filing of the Post-Effective Amendment. We hereby consent to the filing of this opinion with the SEC in connection with the Post-Effective Amendment. In giving our consent we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the 1933 Act or the rules and regulations of the SEC thereunder.

Very truly yours,

Perkins Coie LLP

EX-99.(J)

EX.j.

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form N-1A of our report dated February 17, 2012, relating to the financial statements and financial highlights which appears in the December 31, 2011 Annual Report to Shareholders of Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, which is also incorporated by reference into the Registration Statement. We also consent to the reference to us under the heading “Independent Registered Public Accounting Firm” in such Registration Statement.

PricewaterhouseCoopers LLP

Chicago, Illinois

November 7, 2012

EX-99.(N)(1)

EX.n.1

COLUMBIA ACORN TRUST

Amended and Restated Plan pursuant to Rule 18f-3(d)

under the Investment Company Act of 1940

I. Introduction

Pursuant to Rule 18f-3 under the Investment Company Act of 1940, as amended (the “1940 Act”), this Amended and Restated Plan pursuant to Rule 18f-3(d) under the 1940 Act (“Plan”) sets forth the methods for allocating fees and expenses among the classes of shares (“Shares”) in the series (each a “Fund”) of Columbia Acorn Trust (the “Trust”). Among other things, this Plan identifies expenses that may be allocated to a particular class of Shares to the extent that they are actually incurred in a different amount by that class or if the class receives services of a different kind or to a different degree than other classes. In addition, this Plan sets forth exchange privileges, conversion features, maximum initial sales loads, contingent deferred sales charges, maximum distribution fees, maximum shareholder servicing fees, maximum shareholder administration fees, and other shareholder services and transfer agency fees, if any, applicable or allocated to each class of Shares of the Trust. Each class of Shares is subject to such investment minimums and other conditions of eligibility as are set forth in the then-current prospectus and statement of additional information (“SAI”) for Shares of that class; provided that any material changes to such minimums and conditions shall be treated as an amendment to this Plan subject to Article VI below.

The Trust is an open-end series investment company registered under the 1940 Act. The Trust offers multiple classes of Shares in its Funds pursuant to the provisions of Rule 18f-3 and this Plan. Each Fund and the classes of Shares representing interests in the Fund it issues are set forth in Schedule I attached hereto.

This Plan, as amended and restated, shall be effective as of November 8, 2012.

II. Allocation of Expenses

A. All expenses of each Fund shall be allocated proportionately among the classes of Shares of such Fund pro rata based on the relative net assets of each class; provided, that each class of Shares shall pay all of the expenses associated with their different arrangements for shareholder services or distribution (as set forth more specifically in Article V below). Each class of Shares may also pay a different share of other expenses, not including advisory or custodial fees or other expenses related to the management of the Trust’s assets, if those expenses are actually incurred in a different amount by the class of Shares or if the class of Shares receives services of a different kind or to a different degree than other classes of Shares.

B. The officers of the Trust shall have the authority to determine, to the extent permitted by applicable law or regulation and/or U.S. Securities and Exchange Commission guidance, whether any or all of the fees and expenses described in paragraph A above should be allocated to a particular class of Shares. The Treasurer, any Deputy or Assistant Treasurer, or another

appropriate officer of the Trust shall periodically or as frequently as requested by the Board report to the Board of Trustees regarding any such allocations.

C. Transfer agency costs vary among classes, and are calculated at the following rates:

• Class A, Class B, Class C, Class R, Class R4 and Class Z: Transfer agent fee of $18.50 per account until May 1, 2013 and $20.00 thereafter; reimbursement of sub-transfer agency fees of 0.115% per account until May 1, 2013 and 0.18% thereafter on assets held in omnibus retirement plans; and $12.25 per account until May 1, 2013 and $14.00 thereafter on open accounts beneficially invested in the Funds through an omnibus account maintained at a broker dealer or fund supermarket.

• Class R5 Shares: Transfer agent fee of $18.50 per account until May 1, 2013 and $20.00 thereafter; reimbursement of sub-transfer agency fees of 0.115% per account until May 1, 2013 and 0.18% thereafter on assets held in omnibus retirement plans; and $12.25 per account until May 1, 2013 and $14.00 thereafter on open accounts beneficially invested in the Funds through an omnibus account maintained at a broker dealer or fund supermarket; provided that reimbursement of sub-transfer agency fees is subject to an annual limit of 0.05% of the average daily net assets of the class.

• Class Y Shares: Transfer agent fee of $18.50 per account until May 1, 2013 and $20.00 thereafter; no sub-transfer agency fees.

• Class I Shares: No transfer agent or sub-transfer agency fees.

D. In certain cases, a Fund service provider may waive or reimburse all or a portion of the expenses of a specific class of Shares of the Fund. The applicable service provider shall report to the Board of Trustees regarding any such waivers or reimbursements, including why they are consistent with the fair and equitable treatment of shareholders of all classes.

III. Exchange Privileges

Each class of Shares of a Fund shall have such exchange privileges, if any, as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such class of Shares of such Fund. Each class of Shares of a Fund may generally be exchanged for the identical class of Shares of any other Fund or funds (“Columbia Funds”) in the fund family that is comprised of the open-end investment management companies advised by Columbia Management Investment Advisers, LLC or its affiliates and principally underwritten by Columbia Management Investment Distributors, Inc. (the “Distributor”), subject to exceptions described in the then-current prospectuses of the Fund and/or Columbia Fund. In addition, each class of Shares of a Fund may generally be exchanged for another class of Shares of any other Fund or Columbia Fund, subject to the shareholder’s satisfaction of the eligibility requirements of the other class of Shares.

In general, a shareholder may exchange shares of one class of shares of a Fund for another class of shares of the same Fund, subject to the shareholder’s satisfaction of the eligibility requirements of the other class of Shares. If a shareholder becomes eligible, in accordance with the eligibility requirements described in the then-current prospectuses of a Fund, to purchase

2

Class Z Shares of the Fund, Shares of eligible classes may be exchanged for Class Z Shares of the same Fund, subject to the terms set forth in the prospectuses. A Columbia Fund that holds Class Z Shares of a Fund may exchange such Shares for Class I Shares of the same Fund, subject to exceptions described in the then-current prospectuses of the Columbia Fund and Fund. Effective March 29, 2013, Class Z Shares of a Fund may be exchanged, without the payment of a sales charge, at the holder’s option, for Class A Shares of the same Fund for accounts of selling agents that clear Fund Share transactions for their client or customer accounts through designated mutual fund trading platforms that have agreements with the Distributor and/or Columbia Management Investment Services Corp.

IV. Conversion Features

Class B Shares of a Fund automatically convert to Class A Shares of the same Fund eight years after purchase, except that Class B Shares purchased through the reinvestment of dividends and other distributions on Class B Shares convert to Class A Shares in the same percentage as the amount of Class B Shares otherwise being converted, or otherwise as described in the then-current prospectus for such Shares of such Fund.

V. Class Arrangements

CLASS A SHARES

A. Maximum Initial Sales Load: Initial sales charges may not exceed 5.75%, and may be reduced or waived as permitted by Rule 22d-1 under the Investment Company Act of 1940 (the “1940 Act”) and as described in each Fund’s then-current prospectus and SAI for Class A Shares.

B. Contingent Deferred Sales Charge: Class A Shares bought before September 3, 2010 without an initial sales charge in accounts aggregating $1 million to $50 million at the time of purchase that are redeemed within one year of the time of purchase are subject to a contingent deferred sales charge (“CDSC”) of 1.00% of either the purchase price or the NAV of the Shares at the time of redemption, whichever is less.

Class A Shares bought after September 3, 2010 without an initial sales charge in accounts aggregating $1 million to $50 million at the time of purchase that are redeemed within 18 months of the time of purchase are subject to a CDSC that is charged as follows:

• 1.00% of either the purchase price or the NAV of the Shares at the time of redemption, whichever is less, on Shares redeemed within 12 months of purchase; and

• 0.50% of either the purchase price or the NAV of the Shares at the time of redemption, whichever is less, on Shares redeemed more than 12, but less than 18, months after purchase.

Subsequent Class A Share purchases that bring the value of an account above $1 million (but less than $50 million) are subject to a CDSC of 1.00% (if redeemed within 12 months of purchase) or 0.50% (if redeemed more than 12 months but less than 18 months of purchase) of either the

3

purchase price or the NAV of the Shares at the time of redemption, whichever is less. The period for purposes of calculating the Class A Shares CDSC begins on the first day of the month in which the purchase was made. For purposes of applying the CDSC, the Fund will first redeem any Shares that are not subject to a CDSC, followed by those held for the longest period of time. Class A Shares purchased with reinvested dividends and other distributions are not subject to an initial sales charge or CDSC. The CDSC does not apply to certain accounts, as described in each Fund’s then-current prospectus and SAI for Class A Shares. The CDSC may be reduced or waived by each Fund in certain circumstances as permitted by Rule 6c-10 under the 1940 Act, and as described in the Fund’s then-current prospectus and SAI for Class A Shares.

No CDSC shall be charged on the exchange of Class A Shares of a Fund for Class A Shares of another Columbia Fund. If the Class A Shares received in the exchange are subsequently redeemed, the amount of the CDSC, if any, will be determined by the schedule of the Columbia Fund in which the original investment was made, and the holding period for determining the CDSC will include the holding period of the Shares exchanged.

C. Maximum Distribution/Shareholder Servicing Fees: Class A Shares of each Fund pay a service fee pursuant to a plan adopted pursuant to Rule 12b-1 under the 1940 Act (“Rule 12b-1 Plan”) as described in each Fund’s then-current prospectus and SAI for Class A Shares in an amount up to 0.25% per annum of the average daily net assets attributable to Class A Shares.

D. Other Shareholder Services: Class A Shares of each Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS B SHARES

Each Fund no longer permits purchases of Class B Shares. Additional Class B Shares of each Fund will be issued only to existing Class B shareholders in connection with:

• the reinvestment of dividends and/or capital gain distributions on Class B Shares of the same Fund; and

• exchanges of Class B Shares of another Columbia Fund (not including another series of the Trust), as may be permitted by the Columbia Fund’s then-current prospectus for Class B Shares.

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: Class B Shares of a Fund that are redeemed within the period of time after purchase (not more than 6 years) specified in the Fund’s then-current prospectus and SAI for Class B Shares are subject to a CDSC of up to 5.00% of either the purchase price or the NAV of the Shares at the time of redemption, whichever is less; such percentage may be lower for certain Funds, and declines the longer the Shares are held, all as described in the Fund’s then-current prospectus and SAI for Class B Shares. For purposes of applying the CDSC, the Fund will first redeem any Shares that are not subject to a CDSC, followed by those held for the longest period of time. Class B Shares purchased with reinvested dividends and other distributions are not subject to a CDSC, nor are amounts representing

4

appreciation in the value of, income earned on, or capital gains paid by Class B Shares. The CDSC on Shares of each Fund may be reduced or waived in certain circumstances, as permitted by Rule 6c-10 under the 1940 Act, and as described in the Fund’s then-current prospectus and SAI for Class B Shares.

The holding period for determining the CDSC and the conversion to Class A Shares for the Class B Shares received in the exchange will include the holding period of the Shares exchanged. If the Class B Shares received in the exchange are subsequently redeemed, the amount of the CDSC, if any, will be determined by the schedule of the Columbia Fund in which the original investment was made.

C. Maximum Distribution/Shareholder Servicing Fees: Class B Shares of each Fund pay distribution and shareholder servicing fees pursuant to a Rule 12b-1 Plan as described in the Fund’s then-current prospectus and SAI for Class B Shares of up to, respectively, 0.50% and 0.25% per annum of the average daily net assets attributable to Class B Shares.

D. Other Shareholder Services: Class B Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS C SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: Class C Shares that are redeemed within one year of purchase may be subject to a CDSC of 1.00% of either the purchase price or the NAV of the Shares at the time of redemption, whichever is less. The period for purposes of calculating the Class C Shares CDSC begins on the first day of the month in which the purchase was made. For purposes of applying the CDSC, the Fund will first redeem any Shares that are not subject to a CDSC, followed by those held for the longest period of time. Class C Shares purchased with reinvested dividends or other distributions are not subject to a CDSC, nor are amounts representing appreciation in the value of, income earned on, or capital gains paid by Class C Shares. The CDSC on Shares of each Fund may be reduced or waived in certain circumstances as permitted by Rule 6c-10 under the 1940 Act, and as described in the Fund’s then-current prospectus and SAI for Class C Shares.

If the Class C Shares received in the exchange are subsequently redeemed, the amount of the CDSC, if any, will be determined by the schedule of the Columbia Fund in which the original investment was made, and the holding period for determining the CDSC will include the holding period of the Shares exchanged.

5

C. Maximum Distribution/Shareholder Servicing Fees: Class C Shares pay distribution and service fees pursuant to a Rule 12b-1 Plan as described in the each Fund’s then-current prospectus and SAI for Class C Shares of up to, respectively, 0.75% and 0.25% per annum of the average daily net assets attributable to Class C Shares.

D. Other Shareholder Services: Class C Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS I SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: None

C. Maximum Distribution/Shareholder Servicing Fees: None

D. Other Shareholder Services: Class I Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS R SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: None

C. Maximum Distribution/Shareholder Servicing Fees: Class R Shares pay distribution fees pursuant to a Rule 12b-1 Plan as described in the Fund’s then-current prospectus and SAI for Class R Shares of up to 0.50% per annum of the average daily net assets attributable to such class.

D. Other Shareholder Services: Class R Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS R4 SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: None

C. Maximum Distribution/Shareholder Servicing Fees: None

D. Other Shareholder Services: Class R4 Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

6

CLASS R5 SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: None

C. Maximum Distribution/Shareholder Servicing Fees: None

D. Other Shareholder Services: Class R% Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS Y SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: None

C. Maximum Distribution/Shareholder Servicing Fees: None

D. Other Shareholder Services: Class Y Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

CLASS Z SHARES

A. Maximum Initial Sales Load: None

B. Contingent Deferred Sales Charge: None

C. Maximum Distribution/Shareholder Servicing Fees: None

D. Other Shareholder Services: Class Z Shares of a Fund shall have such arrangements for shareholder services as are determined by or ratified by the Board of Trustees of the Trust and described in the then-current prospectus for such Shares of such Fund.

VI. Board Review and Approvals

The Board of Trustees of the Trust shall review this Plan, including the application of the allocation methodologies described herein to the Funds, as frequently as it deems necessary. No new classes of Shares may be added to any Fund, nor may this Plan or the shareholder servicing arrangements described in the then-effective prospectuses and SAI be materially amended, unless the Board of Trustees of the Trust, including a majority of the trustees who are not interested persons of the Trust, shall find that the Plan, as proposed to be amended (including any proposed amendments to the method of allocating class and/or Fund expenses), is in the best interests of each class of Shares of the Fund individually and the Fund as a whole and is otherwise permitted by law and by the Agreement and Declaration of Trust and By-laws of the Trust. In considering whether to approve any proposed amendment(s) to the Plan, the Board of

7

Trustees of the Trust shall request and evaluate such information as they consider reasonably necessary to evaluate the proposed amendment(s) to the Plan.

Last Approved by the Board of Trustees: September 19, 2012

8

SCHEDULE I

Share Classes Offered by the Columbia Acorn Funds

	Class A	Class B	Class C	Class Z	Class I	Class R	Class R4	Class R5	Class Y
Columbia Acorn Fund	X	X*	X	X	X		X	X	X
Columbia Acorn International	X	X*	X	X	X	X	X	X	X
Columbia Acorn USA	X	X*	X	X	X		X	X	X
Columbia Acorn Select	X	X*	X	X	X		X	X	X
Columbia Acorn International Select	X	X*	X	X	X		X	X	X
Columbia Thermostat Fund	X	X*	X	X			X	X	X
Columbia Acorn European Fund	X		X	X	X			X
Columbia Acorn Emerging Markets Funds	X		X	X	X		X	X

* The Funds no longer accept investments from new or existing investors in Class B Shares. Additional Class B Shares of the Fund will be issued only in connection with the reinvestment of dividends and/or capital gain distributions in Class B Shares of the Fund by the Fund’s existing Class B shareholders.

Last approved by the Board of Trustees: September 19, 2012

EX-99.(P)(2)

EX.p.2

COLUMBIA ACORN TRUST

WANGER ADVISORS TRUST

Code of Ethics

for

Non-Management Trustees

The Investment Company Act of 1940, as amended (the “1940 Act”) and rules thereunder require that Columbia Acorn Trust and Wanger Advisors Trust (the “Trusts”) establish standards and procedures for the detection and prevention of certain conflicts of interest, including activities by which persons having knowledge of the investments and investment intentions of the series of each Trust (each a “Fund” and collectively, the “Funds”) might take advantage of that knowledge for their own benefit. For that purpose, the Board of Trustees of each Trust (together, the “Board”) has adopted this Code of Ethics (the “Code”) applicable to (i) each Trustee who is not an “interested person” of the Funds within the meaning of Section 2(a)(19) of the 1940 Act ) (“Independent Trustees”) and (ii) certain other Trustees or Trustees emeriti (collectively, “Non-Management Trustees”). The Non-Management Trustees are listed on Appendix A hereto.

Any questions about the Code or about the applicability of the Code to a personal securities transaction should be directed to the designated compliance officer of Columbia Wanger Asset Management, LLC (“CWAM”), the investment adviser of the Trusts, the Trusts’ chief compliance officer or counsel for the Trusts or the Independent Trustees.

I. STATEMENT OF PRINCIPLE

General Prohibitions. The 1940 Act and rules thereunder make it illegal for any person covered by the Code, directly or indirectly, in connection with the purchase or sale of a Covered Security, as defined below, which, within the most recent 15 days (i) has been held by or (ii) is being purchased or sold or (iii) has been considered by a Fund or CWAM for purchase or sale by a Fund to:

A. employ any device, scheme, or artifice to defraud the Fund;

B. make to the Fund any untrue statement of a material fact or omit to state to the Fund a material fact necessary in order to make the statements made, in light of circumstances under which they are made, not misleading;

C. engage in any act, practice, or course of business which operates or would operate as a fraud or deceit upon the Fund; or

D. engage in any manipulative practice with respect to the Fund.

In any situation where the potential for conflict exists, transactions for a Fund must take precedence over any personal transaction. Non-Management Trustees owe a duty to each

Fund and its shareholders to conduct their personal securities transactions in a manner which does not interfere with the portfolio transactions of the Fund, take inappropriate advantage of their relationship with the Fund, or create any actual or potential conflict of interest between their interests and the interests of the Fund and its shareholders.

Situations not specifically governed by this Code of Ethics will be resolved in light of this general principle.

Personal Securities Transactions. The Code regulates personal securities transactions as a part of the effort by the Funds to detect and prevent conduct that might violate the general prohibitions outlined above. A personal securities transaction is a transaction in a Covered Security held in any account over which the Non-Management Trustee has a beneficial interest, as defined below.

Covered Security is interpreted very broadly for this purpose, and includes any right to acquire any security (an option or warrant, for example).

You have a beneficial interest in a security in which you have, directly or indirectly, the opportunity to profit or share in any profit derived from a transaction in the security, or in which you have an indirect interest, including beneficial ownership by your spouse or minor children or other dependents living in your household, or your share of securities held by a partnership of which you are a general partner. Technically, the rules under section 16 of the Securities Exchange Act of 1934 will be applied to determine if you have a beneficial interest in a security (even if the security would not be within the scope of section 16). Examples of beneficial interest and a copy of Rule 16a-1(a), defining beneficial ownership, are attached as Appendix B.

II. TO WHOM THE CODE’S RESTRICTIONS APPLY

The Code applies to Non-Management Trustees.

III. RESTRICTIONS ON PERSONAL SECURITIES TRANSACTIONS

A. No Transactions with the Funds. No Non-Management Trustee shall knowingly sell to or purchase from the Funds any security or other property, except securities issued by the Funds.

B. No Conflicting Transactions. If a Non-Management Trustee knows or in the ordinary course of fulfilling his or her duties as a Trustee should have known that a Covered Security is being purchased or sold or considered for purchase or sale by any Fund, the Trustee shall not purchase or sell the security in a transaction in which the Trustee has a beneficial interest.

IV. COMPLIANCE PROCEDURES

A. Quarterly Reporting of Personal Securities Transactions.

1. Each Non-Management Trustee shall report to CWAM’s compliance officer, within ten days after the end of any calendar quarter in which the Trustee had a transaction in a Covered Security in which the Trustee acquired any direct or indirect beneficial interest, if the Trustee knew, or in the ordinary course of fulfilling his or her official duties as a Trustee

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should have known, that during the 15 day period immediately before or after the Trustee’s transaction in a Covered Security a Fund or CWAM purchased or sold the Covered Security or considered purchasing or selling the Covered Security.

2. Quarterly reports of personal securities transactions for Non-Management Trustees may be in any form (including copies of confirmations or monthly statements) but must include (i) the date of the transaction, the title and number of shares, and the principal amount of each security involved; (ii) the nature of the transaction (i.e., purchase, sale, gift, or other type of acquisition or disposition); (iii) the price at which the transaction was effected; (iv) the name of the broker, dealer, or bank with or through whom the transaction was effected; and (v) the name of the reporting person.

B. Monitoring of Transactions. CWAM’s compliance officer will review the quarterly reports of personal securities transactions of each Fund’s Non-Management Trustees.

D. Certification of Compliance. Each Non-Management Trustee is required to certify annually that he or she has read and understands the Code and recognizes that he or she is subject to the Code. To accomplish this, the Secretary of the Funds shall annually distribute a copy of the Code and request certification.

E. Review by the Board. The officers of the Funds shall prepare an annual report to the Board that:

1. summarizes existing procedures concerning personal investing and any changes in those procedures during the past year;

2. identifies any violations of the Code requiring significant remedial action during the past year; and

3. identifies any recommended changes in existing restrictions or procedures based upon experience under the Code, evolving industry practices, or developments in applicable laws or regulations.

V. EXEMPT TRANSACTIONS

The provisions of this Code are intended to restrict the personal investment activities of persons subject to the Code only to the extent necessary to accomplish the purposes of the Code. Therefore, the provisions of Section III (Restrictions on Personal Securities Transactions) and Section IV (Compliance Procedures) of this Code shall not apply to:

A. Purchases or sales effected in any account over which a person subject to this Code may have a beneficial interest, but no direct or indirect influence or control of investment or trading activity, such as a blind trust;

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B. Purchases or sales of:

1. U.S. government securities;

2. shares of open-end investment companies (mutual funds), including but not limited to shares of any of the Funds; and

3. bank certificates of deposit or commercial paper.

C. Purchases that are part of an automatic dividend reinvestment plan;

D. Purchases effected upon the exercise of rights issued by an issuer pro rata to all holders of a class of securities to the extent such rights were acquired from such issuer, and sales of such rights so acquired;

E. Purchases or sales that receive the prior approval of the Funds’ chief compliance officer because they are not inconsistent with this Code or the provisions of Rule 17j-1(a) under the 1940 Act.

VI. CONSEQUENCES OF FAILURE TO COMPLY WITH THE CODE

Compliance with this Code is a condition of retention of positions with the Funds. The Board shall determine what action is appropriate for any breach of the provisions of the Code by a Non-Management Trustee, which may include removal from the Board.

Reports filed pursuant to the Code will be maintained in confidence but will be reviewed by CWAM or the Funds to verify compliance with the Code. Additional information may be required to clarify the nature of particular transactions.

VII. RETENTION OF RECORDS

CWAM’s designated compliance officer shall maintain the records listed below for a period of five years at the Funds’ principal place of business in an easily accessible place:

A. a list of all persons subject to the Code during the period;

B. receipts signed by all persons subject to the Code acknowledging receipt of copies of the Code and acknowledging that they are subject to it;

C. a copy of each code of ethics that has been in effect at any time during the period; and

D. a copy of each report filed pursuant to the Code and a record of any known violation and action taken as a result thereof during the period.

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Columbia Acorn Trust:

Adopted effective 5/28/96

Amended effective 5/25/99

Amended effective 9/29/00

Amended effective 5/23/01

Amended effective 3/4/02

Amended effective 11/16/04

Amended effective 6/6/06

Amended effective 9/26//06

Amended effective 7/27/10

Amended effective 9/22/10

Amended effective 9/21/11

Amended effective 9/19/12

Wanger Advisors Trust:

Adopted effective 6/15/96

Amended effective 6/8/99

Amended effective 9/29/00

Amended effective 6/5/01

Amended effective 12/28/03

Amended effective 6/7/06

Amended effective 9/26//06

Amended effective 7/27/10

Amended effective 9/22/10

Amended effective 9/21/11

Amended effective 9/19/12

Appendix A

Non-Management Trustees

Laura M. Born

Michelle L. Collins

Maureen M. Culhane

Margaret M. Eisen

John C. Heaton

Steven Kaplan

David J. Rudis

David B. Small

Ralph Wanger

Appendix B

Examples of Beneficial Ownership

For purposes of the Code, you will be deemed to have a beneficial interest in a security if you have the opportunity, directly or indirectly, to profit or share in any profit derived from a transaction in the security. Examples of beneficial ownership under this definition include:

• securities you own, no matter how they are registered, and including securities held for you by others (for example, by a custodian or broker, or by a relative, executor or administrator) or that you have pledged to another (as security for a loan, for example);

• securities held by a trust of which you are a beneficiary (except that, if your interest is a remainder interest and you do not have or participate in investment control of trust assets, you will not be deemed to have a beneficial interest in securities held by the trust);

• securities held by you as trustee or co-trustee, where either you or any member of your immediate family (i.e., spouse, children or descendants, stepchildren, parents and their ancestors, and stepparents, in each case treating a legal adoption as blood relationship) has a beneficial interest (using these rules) in the trust;

• securities held by a trust of which you are the settlor, if you have the power to revoke the trust without obtaining the consent of all the beneficiaries and have or participate in investment control;

• securities held by any partnership in which you are a general partner, to the extent of your interest in partnership capital or profits;

• securities held by a personal holding company controlled by you alone or jointly with others;

• securities held by (i) your spouse, unless legally separated, or you and your spouse jointly, or (ii) your minor children or any immediate family member of you or your spouse (including an adult relative), directly or through a trust, who is sharing your home, even if the securities were not received from you and the income from the securities is not actually used for the maintenance of your household; or

• securities you have the right to acquire (for example, through the exercise of a derivative security), even if the right is not presently exercisable, or securities as to which, through any other type of arrangement, you obtain benefits substantially equivalent to those of ownership.

You will not be deemed to have beneficial ownership of securities in the following situations:

• securities held by a limited partnership in which you do not have a controlling interest and do not have or share investment control over the partnership’s portfolio; and

• securities held by a foundation of which you are a trustee and donor, provided that the beneficiaries are exclusively charitable and you have no right to revoke the gift.

Appendix B

These examples are not exclusive. There are other circumstances in which you may be deemed to have a beneficial interest in a security. Any questions about whether you have a beneficial interest should be directed to CWAM’s designated compliance officer or chief operating officer.

Attachment A

COLUMBIA ACORN TRUST

WANGER ADVISORS TRUST

Code of Ethics Affirmation

I affirm that I have received a copy of the Columbia Acorn Trust and Wanger Advisors Trust Code of Ethics for Non-Management Trustees (the “Code”) and have read and understand it. I acknowledge that I am subject to the Code and will comply with the Code in all respects.

Date:                         

Signature