Columbia Acorn Trust

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund

Investment Objective

Columbia Acorn Emerging Markets Fund^SM (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 24 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	1.00% ^(b)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees	1.04%	1.04%	1.04%	1.04%	1.04%	1.04%	1.04%
Distribution and/or service (12b-1) fees	0.25%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.28%	0.29%	0.17%	0.24%	0.22%	0.17%	0.29%
Total annual Fund operating expenses	1.57%	2.33%	1.21%	1.28%	1.26%	1.21%	1.33%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

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 the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$726	1,042	$1,381	$2,335
Class C (assuming redemption of all shares at the end of the period)	$336	727	$1,245	$2,666
Class C (assuming no redemption of shares)	$236	727	$1,245	$2,666
Class I (whether or not shares are redeemed)	$123	384	$ 665	$1,466
Class R4 (whether or not shares are redeemed)	$130	406	$ 702	$1,545
Class R5 (whether or not shares are redeemed)	$128	400	$ 692	$1,523
Class Y (whether or not shares are redeemed)	$123	384	$ 665	$1,466
Class Z (whether or not shares are redeemed)	$135	421	$ 729	$1,601

Portfolio Turnover

The Fund may pay 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 45% of the average value of its portfolio.

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 initial 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. Under normal circumstances, the Fund may invest in companies with market capitalizations above $5 billion at the time of initial investment, provided that immediately after that investment a majority of its net assets would be invested in companies whose market capitalizations were under $5 billion at the time of initial investment.

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.

4	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

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 in which the company has 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

An investment in the Fund involves risk, including those described below. There is no assurance that the Fund will achieve its investment objective and you may lose money. The value of the Fund’s holdings may decline, and the Fund’s net asset value (NAV) and share price may go down.

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

security will not be delivered to the Fund or that payment will not be received. 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. In certain non-U.S. markets, an issuer’s securities are blocked from trading for a specified number of days before and, in certain instances, after a shareholder meeting. The blocking period can last up to several weeks. Share blocking may prevent the Fund from buying or selling securities during this period. 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, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries, and some have a higher risk of currency devaluations.

Operational and Settlement Risks of Securities in Emerging Markets. Foreign sub-custodians in emerging markets 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. There may also 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.

Frontier Market Risk. Frontier market countries generally have smaller economies and even less developed capital markets than traditional emerging market countries (which themselves have increased investment risk relative to more developed market countries) and, as a result, the Fund’s exposure to the risks associated with investing in emerging market countries are magnified when the Fund invests in frontier market countries. Increased risks include: the potential for extreme price volatility and illiquidity in frontier market countries; government ownership or control of parts of the private sector and of certain companies; trade barriers, exchange controls, managed adjustments in relative currency values and other protectionist and similar 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.

Small- and Mid-Cap Company Securities Risk. Investments in small- and mid-capitalization companies (small- and mid-cap companies) often involve greater risks than investments in larger, more established companies (larger companies) because small- and mid-cap companies tend to have less predictable earnings and may lack the management experience, financial resources, product diversification and competitive strengths of larger companies. Securities of small- and mid-cap companies may be less liquid and more volatile than the securities of larger companies.

6	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

Sector Risk. At times, the Fund may have a significant portion of its assets invested in securities of companies conducting business in a related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic, regulatory, political or market events or conditions, which may make the Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly. Generally, the more the Fund diversifies its investments, the more it spreads risk and potentially reduces the risks of loss and volatility.

Issuer Risk. An issuer in which the Fund invests may perform poorly, and the value of its securities may therefore decline, which would negatively affect the Fund’s performance. Poor performance may be caused by poor management decisions, competitive pressures, breakthroughs in technology, reliance on suppliers, labor problems or shortages, corporate restructurings, fraudulent disclosures, natural disasters or other events, conditions or factors.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

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. The bar chart shows how the Fund’s Class Z share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with the Standard & Poor’s (S&P) Emerging Markets Between $500 Million and $5 Billion^® Index, the Fund's primary benchmark, and the MSCI Emerging Markets Small Cap Index (Net). The S&P Emerging Markets Between $500 Million and $5 Billion^® Index is representative of the institutionally investable capital of 20 emerging market countries (as of December 31, 2014), as determined by S&P, with market caps ranging between $500 million to $5 billion. The MSCI Emerging Markets Small Cap Index (Net) is a widely recognized international benchmark, and a free floating-adjusted market capitalization index that is designed to measure small-cap emerging market equity performance in 23 emerging market countries (as of December 31, 2014), as determined by MSCI. The performance of the MSCI Emerging Markets Small Cap Index (Net) is provided to show how the Fund's performance compares to a widely recognized index of small-capitalization equity performance in less developed markets.

The performance of one or more share classes shown in the Average Annual Total Returns table below includes the Fund’s Class Z share returns (adjusted to reflect the higher class-related operating expenses of such classes, where applicable) for periods prior to the indicated inception date of such share classes. Except for differences in fees and expenses, all share classes of the Fund would have substantially similar annual returns because all share classes of the Fund invest in the same portfolio of securities.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

as 401(k) plans or Individual Retirement Accounts (IRAs). The after-tax returns are shown only for Class Z shares and will vary for other share classes. 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.

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 columbiathreadneedle.com/us.

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{1st Quarter 2012}	_18.00%
	_Worst	_{2nd Quarter 2012}	_-6.90%

*	Year to Date return as of March 31, 2015: -0.78%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	Life of Fund
Class Z	08/19/2011
returns before taxes		-4.12%	8.29%
returns after taxes on distributions		-4.16%	8.20%
returns after taxes on distributions and sale of Fund shares		-2.02%	6.56%
Class A returns before taxes	08/19/2011	-9.81%	6.12%
Class C returns before taxes	08/19/2011	-5.98%	7.22%
Class I returns before taxes	08/19/2011	-4.01%	8.42%
Class R4 returns before taxes	11/08/2012	-4.03%	8.38%
Class R5 returns before taxes	11/08/2012	-4.02%	8.39%
Class Y returns before taxes	06/13/2013	-3.95%	8.40%
S&P Emerging Markets Between $500 Million and $5 Billion^® Index (reflects no deductions for fees, expenses or taxes)		1.90%	3.31%
MSCI Emerging Markets Small Cap Index (Net) (reflects reinvested dividends net of withholding taxes but reflects no deductions for fees, expenses or other taxes)		1.01%	1.16%

8	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Fritz Kaegi, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since inception in 2011	2011
Stephen Kusmierczak, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since inception in 2011	2011
Louis J. Mendes, CFA	Portfolio Manager and Analyst	Co-manager since inception in 2011	2011
Satoshi Matsunaga, CFA	Portfolio Manager and Analyst	Co-manager since 2015	2011

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

You may purchase shares and receive redemption proceeds by electronic funds transfer, by check or by wire. If you maintain your account with a broker-dealer or other financial intermediary, you must contact that financial intermediary to buy, sell or exchange shares of the Fund through your account with the intermediary.

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A & C	All accounts other than IRAs	$2,000	$100
Classes A & C	IRAs	$1,000	$100
Classes I, R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

There is no minimum additional investment for any share class.

Effective July 11, 2014, the Fund is closed to most new investors and new accounts. See Buying, Selling and Exchanging Shares — Buying Shares — Eligible Investors — Fund Closed to Most New Investors and New Accounts in the prospectus for more information.

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, qualified dividend income or capital gains, unless you are 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.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Summary of the Fund (continued)

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, 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. These potential conflicts of interest may be heightened with respect to broker-dealers owned by Ameriprise Financial and/or its affiliates. In addition, the Fund compensates the Transfer Agent for the costs of shareholder services that vary across financial intermediaries. The Fund seeks to provide such compensation to the Transfer Agent at levels it believes to be reasonable, but because of the variety of type and cost of services provided by different intermediaries, there can be no assurance that the Fund is able to identify to which specific services the compensation relates. Ask your financial advisor or visit your financial intermediary's website for more information.

10	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

More Information About the Fund

Investment Objective

Columbia Acorn Emerging Markets Fund^SM (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

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 in which the company has a competitive advantage.

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

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

More Information About the Fund (continued)

Principal Risks

Active Management Risk. The Fund is actively managed and its performance therefore will reflect, in part, the ability of the Investment Manager to select investments and to make investment decisions that will achieve the Fund’s investment objective. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives and/or strategies.

Liquidity and Trading Volume Risk. Due to market conditions, including uncertainty regarding the price of a security, it may be difficult for the Fund to buy or sell portfolio securities at a desirable time or price, which could result in investment losses. This risk of portfolio illiquidity is heightened with respect to small- and mid-cap securities, generally, and foreign small- and mid-cap securities in particular. The Fund may have to lower the selling price, liquidate other investments, or forego another, more appealing investment opportunity as a result of illiquidity in the markets. The Investment Manager will fair value in good faith any securities it deems to be illiquid under consistently applied procedures established by the Fund’s Board. Market conditions are always changing and vary by country and industry sector, and investing in international markets involves unique risks. In the wake of the 2007-2009 financial crisis, trading volumes in both emerging and developed international markets declined significantly and have stayed at generally reduced levels since then. Although it is difficult to accurately assess trends in trading volumes in foreign markets, because some amount of activity has migrated to alternative trading venues, a reduction in trading volumes poses challenges to the Fund. This is particularly so because the Fund focuses on small- and mid-cap companies that usually have lower trading volumes and often takes sizeable positions in portfolio companies. As a result of lower trading volumes, it may take longer to buy or sell securities, which can exacerbate the Fund’s exposure to volatile markets. The Fund may also be limited in its ability to execute favorable trades in portfolio securities in response to changes in share prices and fundamentals. If the Fund is forced to sell securities to meet redemption requests or other cash needs, or in the case of an event affecting liquidity in a particular market or markets, it may be forced to dispose of those securities under disadvantageous circumstances and at a loss. As the Fund grows in size, these considerations take on increasing significance and may adversely impact performance.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar. Foreign securities may also be less liquid than securities of U.S. companies so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

12	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

More Information About the Fund (continued)

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, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with 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.

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

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

More Information About the Fund (continued)

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 China and Russia.

Frontier Market Risk. Frontier market countries generally have smaller economies and even less developed capital markets than typical emerging market countries (which themselves have increased investment risk relative to more developed market countries) and, as a result, the Fund’s exposure to risks associated with investing in emerging market countries are magnified when the Fund invests in frontier market countries. The increased risks include: the potential for extreme price volatility and illiquidity in frontier market countries; government ownership or control of parts of the 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. Securities issued by foreign governments or companies in frontier market countries are even more likely than emerging markets securities to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk.

Foreign Currency Risk. The performance of the Fund may be materially affected positively or negatively by foreign currency strength or weakness relative to the U.S. dollar, particularly if the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar. Currency rates in foreign countries may fluctuate significantly over short or long periods of time for a number of reasons, including changes in interest rates, imposition of currency controls and economic or political developments in the U.S. or abroad. The Fund may also incur currency conversion costs when converting foreign currencies into U.S. dollars and vice versa.

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

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Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

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 be exposed to heightened 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. Initial public offerings are subject to many of the same risks as investing in companies with smaller market capitalizations. To the extent the Fund determines to invest in initial public offerings, it may not be able to invest to the extent desired, because, for example, only a small portion (if any) of the securities being offered in an initial public offering are available to the Fund. The investment performance of the Fund during periods when it is unable to invest significantly or at all in initial public offerings may be lower than during periods when the Fund is able to do so. Securities purchased in initial public offerings which are sold within 12 months after purchase may result in increased short-term capital gains, which will be taxable to the Fund’s shareholders as ordinary income. Certain “special situation” investments are investments in securities or other instruments that are determined to be illiquid or lacking a readily ascertainable fair value. Certain special situation investments prevent ownership interests therein from being withdrawn until the special situation investment, or a portion thereof, is realized or deemed realized, which may negatively impact Fund performance. Investing in special situations may have a magnified effect on the performance of funds with small amounts of assets.

Additional Investment Strategies and Policies

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

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 Board without shareholder approval, but may require notice to shareholders in certain instances. The Fund’s fundamental investment policies, as identified in the Fund’s 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 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 based on the characteristics of a company at the time of initial purchase, and subsequent changes in a characteristic are not taken into account.

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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/or in the 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. Information on the Fund’s holdings can be found in the Fund’s shareholder reports or by visiting columbiathreadneedle.com/us.

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.

Investing in Affiliated Funds

The Investment Manager and its affiliate, Columbia Management Investment Advisers, LLC (Columbia Management), each serves as investment adviser to mutual funds using the Columbia brand (Columbia Funds), including those that are structured as “fund-of-funds”, and provides asset-allocation services to (i) shareholders by investing in shares of other Columbia Funds, which may include the Fund (collectively referred to in this section as Underlying Funds), and (ii) discretionary managed accounts (collectively referred to as affiliated products) that invest exclusively in Underlying Funds. These affiliated products, individually or collectively, may own a significant percentage of the outstanding shares of one or more Underlying Funds, and the Investment Manager and Columbia Management seek to balance potential conflicts of interest between the affiliated products and the Underlying Funds in which they invest. The affiliated products’ investment in the Underlying Funds may have the effect of creating economies of scale, possibly resulting in lower expense ratios for the Underlying Funds, because the affiliated products may own substantial portions of the shares of Underlying Funds. However, redemption of Underlying Fund shares by one or more affiliated products could cause the expense ratio of an Underlying Fund to increase, as its fixed costs would be spread over a smaller asset base. Because of large positions of certain affiliated products, the Underlying Funds may experience relatively large inflows and outflows of cash due to affiliated products’ purchases and sales of Underlying Fund shares. Although the Investment Manager or Columbia Management may seek to minimize the impact of these transactions where possible, for example, by structuring them over a reasonable period of time or through other measures, Underlying Funds may experience increased expenses as they buy and sell portfolio securities to manage the cash flow effect related to these transactions. Further, when the Investment Manager or Columbia Management structures transactions over a reasonable period of time in order to manage the potential impact of the buy and sell decisions for the affiliated products, those affiliated products, including funds-of-funds, may pay more or less (for purchase activity), or receive more or less (for redemption activity), for shares of the Underlying Funds than if the transactions were executed in one transaction. In addition, substantial redemptions by affiliated products within a short period of time could require the Underlying Fund to liquidate positions more rapidly than would otherwise be desirable, which may have the effect of reducing or eliminating potential gain or causing it to realize a loss. Substantial redemptions may also adversely affect the ability of the Underlying Fund to implement its investment strategy. The Investment Manager or Columbia Management also has an economic conflict of interest in determining the allocation of affiliated products’ assets among the Underlying Funds, as it earns different fees from the various Underlying Funds.

Investing in Money Market Funds

The Fund may invest cash, including cash collateral received in connection with its securities lending program, in shares of money market funds. These funds are not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government agency. The Fund and its shareholders indirectly bear a portion of the expenses of any money market fund or other fund in which the Fund may invest.

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Lending of Portfolio Securities

The Fund may lend portfolio securities to 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, the borrower does not return a loaned security and the proceeds from sale of the collateral are not sufficient to replace the borrowed security. The Fund invests collateral in a government money market fund.

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, social or other conditions. These investment positions may include, without limitation, investments in money market instruments or holdings of cash or cash equivalents, and may be held by the Fund for as long a period as the Investment Manager deems necessary. The Fund may also temporarily invest in derivatives, such as futures (i.e. index futures) or options on futures for as long a period as deemed necessary when the Investment Manager determines that a temporary defensive position is advisable or necessary to meet anticipated redemption requests, or for other reasons. The Fund may not achieve its investment objective, and the Fund’s performance may be adversely affected, while it is investing defensively.

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, columbiathreadneedle.com/us, 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 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 approximately 30 to 40 days after each month-end. The top 15 holdings may be 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.

Cybersecurity

The Fund, like all companies, may be susceptible to operational and information security risks, including the risk of cyber attacks or failures. As a result, the Fund or its service providers, or the issuers of securities in which the Fund invests, may experience disruptions in business operations that may potentially result in financial losses, the inability of Fund shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, and/or additional compliance costs. The Fund and its shareholders could be negatively impacted as a result. See the discussion of Cyber Risk in the SAI for further information.

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.

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FUNDamentals

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 semiannual report to those addresses shared by two or more accounts. If you wish to receive separate 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 may be 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. Also, a high portfolio turnover rate can mean higher brokerage commissions 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 and other transaction costs will have on its returns. The Fund may sell securities regardless of how long they’ve been held. See the Financial Highlights section of this prospectus for the Fund's portfolio turnover rates for the past five years or since inception, if the Fund has been in operation for less than five years.

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 shareholders redeeming Fund shares could require the Fund to sell portfolio securities at less than opportune times or to hold ready reserves of uninvested cash in amounts larger than might otherwise be the case to meet shareholder redemptions. Either situation could adversely impact the Fund’s performance.

Understanding Annual Fund Operating Expenses

The Fund’s annual operating expenses, as presented in the Annual Fund Operating Expenses table in the Fees and Expenses of the Fund section of this prospectus, generally are based on expenses incurred during the Fund’s most recently completed fiscal year, may vary by share class and are expressed as a percentage (expense ratio) of the Fund’s average net assets during that fiscal year. The expense ratios reflect the Fund’s fee arrangements as of the date of this prospectus and, unless indicated otherwise, are based on expenses incurred during the Fund’s most recent fiscal year. The Fund’s assets will fluctuate, but no adjustments have been or will be made to the expense ratios to reflect any differences in the Fund’s average net assets between the most recently completed fiscal year and the date of this prospectus or a later date. In general, the Fund’s expense ratios will increase as its net assets decrease, such that the Fund’s actual expense ratios may be higher than the expense ratios presented in the Annual Fund Operating Expenses table if assets fall. Any commitment by the Investment Manager and/or its affiliates to waive fees and/or cap (reimburse) expenses is expected, in part, to limit the impact of any increase in the Fund’s expense ratios that would otherwise result because of a decrease in the Fund’s assets in the current fiscal year. The Fund’s annual operating expenses are comprised of (i) investment management fees, (ii) distribution and/or service fees, and (iii) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class.

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FUNDamentals

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 and certain shareholder servicing 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 and shareholder servicing fees applicable to each share class. For more information on these fees, see Choosing a Share Class — Selling Agent Compensation.

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

The Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund through April 30, 2016, so that ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, 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:

Columbia Acorn Emerging Markets Fund
Class A	1.85%
Class C	2.60%
Class I	1.48%
Class R4	1.60%
Class R5	1.53%
Class Y	1.48%
Class Z	1.60%

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 transaction costs and certain other investment-related expenses, 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 arrangement may only be modified or amended with approval from all parties to such arrangements, including the Fund and the Investment Manager.

Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

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.

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to elect Trustees was held on February 27, 2015. 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, which 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 and their affiliates currently provide key services, including investment advisory, administration, distribution, shareholder servicing and transfer agency services, to the Fund and various other funds, including the Columbia Funds, and are paid for providing these services. These service relationships are described below.

The Investment Manager

Columbia Wanger Asset Management, LLC is located at 227 West Monroe Street, Suite 3000, Chicago, Illinois 60606. As of March 31, 2015, the Investment Manager had assets under management of approximately $30.4 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 portfolio transactions. The Investment Manager may use the research and other capabilities 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 1.04% of average daily net assets of the Fund. A discussion regarding the basis for the Board approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Portfolio Managers

Information about the portfolio managers primarily responsible for overseeing the Fund’s investments is shown below. The SAI provides additional information about the portfolio managers, including information relating to compensation, other accounts managed by the portfolio managers and ownership by the portfolio managers of Fund shares.

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Fritz Kaegi, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since inception in 2011	2011
Stephen Kusmierczak, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since inception in 2011	2011
Louis J. Mendes, CFA	Portfolio Manager and Analyst	Co-manager since inception in 2011	2011
Satoshi Matsunaga, CFA	Portfolio Manager and Analyst	Co-manager since 2015	2011

Mr. Kaegi has been associated with the Investment Manager or its predecessors as an investment professional since 2004 and has been a 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.

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Mr. Kusmierczak has been associated with the Investment Manager or its predecessors as an investment professional since 2001 and has been a 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.

Mr. Mendes has been associated with the Investment Manager or its predecessors as an investment professional since 2001 and has been a Vice President of the Trust since 2005. 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.

Mr. Matsunaga has been associated with the Investment Manager or its predecessors as an investment professional since 2005 and has been a Vice President of the Trust since 2015. Mr. Matsunaga began his investment career in 1994 and earned a B.A. in Economics from Keio University (Tokyo) and an M.B.A from the University of Michigan.

The Administrator

Columbia Wanger Asset Management, LLC 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 retains the Sub-Administrator to perform certain of these services (including fund accounting), and 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 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 Columbia Management Investment Distributors, Inc., which is located at 225 Franklin Street, Boston, MA 02110. The Distributor is a registered broker-dealer and an indirect, 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

Columbia Management Investment Services Corp. 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, redemptions and exchanges of Fund shares, calculating and paying distributions, maintaining shareholder records, preparing account statements and providing customer service. The Transfer Agent has engaged DST Systems, Inc., including its affiliate, Boston Financial Data Services, to provide various shareholder or "sub-transfer agency" services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares, pursuant to which the Transfer Agent pays these financial intermediaries for providing certain shareholder services. The Fund generally pays the Transfer Agent a per account fee for each open account and compensates the Transfer Agent for certain out-of-pocket expenses. In addition, subject to certain limitations, the Fund compensates the Transfer Agent for payments made 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. The Transfer Agent is contractually

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obligated to oversee such intermediaries for the purpose of reasonably assuring their compliance with applicable law and the terms of their agreements to provide the shareholder services. For more information about Shareholder Services fees, see Choosing a Share Class — Selling Agent Compensation.

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 More Information About 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. Ameriprise Financial and its other affiliates may also provide services (for which they are compensated) to the Fund, other Columbia 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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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 other Columbia 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 or in holdings of particular portfolio companies that may be made by affiliated entities, including the Fund;

■	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. 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 quarterly (10-Q), annual (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 sec.gov.

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Choosing a Share Class

The Funds

The Columbia Acorn Funds and the other Columbia Funds generally share the same policies and procedures for investor services, as described below. Together, the Fund and the other Columbia Acorn Funds, along with the Columbia Funds, are referred to herein as the Funds.

Funds Contact Information

Additional information about the Funds can be obtained at columbiathreadneedle.com/us,* 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 inactive links and information contained in or otherwise accessible through the referenced websites does not form a part of this prospectus.

FUNDamentals

Selling and/or Servicing Agents

The terms “selling agent” and “servicing agent” (collectively, selling agents) refer to the financial intermediaries that are authorized to sell shares of the Funds. 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 advisers, third party administrators and other financial intermediaries, including Ameriprise Financial and its affiliates.

Omnibus Accounts

The term “omnibus account” refers to a selling agent’s account with the Fund (through the Transfer Agent) that represents the combined holdings of, and transactions in, Fund shares of one or more clients of the selling agent (beneficial shareholders). Omnibus accounts are held in the name of the selling agents and not in the name of the beneficial shareholders invested in the Fund through omnibus accounts.

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.

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

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. The Fund offers the class(es) of shares set forth on the cover of this prospectus and may offer other share classes through a separate prospectus. 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.

Effective as of the close of business on July 11, 2014 (the “Closing Date”), the Fund is closed to most new investors and new accounts, except that, subject to the eligibility requirements of the Fund’s various share classes: (i) shareholders who had opened and funded an account with the Fund as of the Closing Date may continue to make additional purchases of Fund shares in their existing accounts; (ii) a retirement plan generally may continue to make additional purchases of Fund shares and to add new accounts that may purchase Fund shares if the retirement plan or a retirement plan with the same or an affiliated plan sponsor holding Fund shares at the plan level had invested in the Fund as of the Closing Date; and (iii) a discretionary wrap program or similar advisory program that held Fund shares as of the Closing Date generally may continue to make additional purchases of Fund shares and add new accounts that may purchase Fund shares. There is no minimum additional investment for any share class. See Buying, Selling and Exchanging Shares — Buying Shares — Eligible Investors — Fund Generally Closed to New Investors and New Accounts for more information.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: None	None	None	None

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	Front-End Sales Charges^(a)	Contingent Deferred Sales Charges (CDSCs)^(a)	Maximum Distribution and/or Service (12b-1) Fees^(b)
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: None	None	None	Distribution Fee: 0.50%
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: 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	None	None	None

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	Front-End Sales Charges^(a)	Contingent Deferred Sales Charges (CDSCs)^(a)	Maximum Distribution and/or Service (12b-1) Fees^(b)
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None
Class Z	Eligibility: Available only to certain eligible investors, which are subject to different minimum investment requirements, ranging from $0 to $2,000; 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	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 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 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 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. Selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that were given specific written notice from the Transfer Agent of the termination, effective March 29, 2013, 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 have continuously held 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. 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 are not permitted to establish new Class Z accounts or make additional purchases of Class Z shares (other than through reinvestment of distributions).

(d)	For more information on the conversion of Class B shares to Class A shares, see Choosing a Share Class — Sales Charges and Commissions.

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

Sales Charges and Commissions

Sales charges, commissions and distribution and service fees (discussed in a separate sub-section below) compensate selling agents (typically your financial advisor) for selling shares to you and for maintaining and servicing the shares held in your account with them. 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 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 price is invested in those classes. Class A shares have lower ongoing distribution and/or service 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 and service fees that are equal to or more than the front-end sales charge and the distribution and service fees you would pay for Class A shares. Thus, although the full amount of your purchase price of Class B, Class C and Class R shares is invested in a Fund, your return on this money will be reduced by the expected higher annual expenses of Class B, 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 and/or service 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 (through the Transfer Agent, rather than through a selling agent). Sales charges vary depending on the amount of your purchase.

FUNDamentals

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 NAV 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 notifies 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.

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Choosing a Share Class (continued)

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).

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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 after purchase, which is charged as follows: 1.00% CDSC if shares are redeemed within 12 months after purchase; and 0.50% CDSC if shares are redeemed more than 12, but less than 18, months after 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.

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

FUNDamentals

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.

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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%

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Choosing a Share Class (continued)

Class B Shares — CDSC Schedule for the Funds
Number of Years Class B Shares Held	Applicable CDSC*
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 NAV 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.

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, over time Class C shares can incur distribution and/or service fees that are equal to or more than the front-end sales charge and distribution and/or service 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 NAV 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 plan and any applicable CDSC applied when you sell your shares. For more information, see Choosing a Share Class — Distribution and Service Fees.

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

Class R Shares — Sales Charges and Commissions

You don't pay a front-end sales charge when you buy Class R shares or a CDSC when you sell Class R shares. 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.

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 and Class Y shares of the Funds, Class R4 and Class R5 shares of the Funds held in retirement plan accounts and direct purchases of Columbia Money Market Fund shares, which may not be aggregated. Shares of Columbia 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 after 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 and Class Y shares of the Funds, Class R4 and Class R5 shares of the Funds held in retirement plan accounts and direct purchases of Columbia Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund acquired by exchange from other Funds may be combined for LOI purposes.

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Choosing a Share Class (continued)

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.

FUNDamentals

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 under 21, step-child under 21, 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

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Columbia Acorn Emerging Markets Fund^SM

Choosing a Share Class (continued)

the shareholder's death; that result from required minimum distributions taken from retirement accounts when the shareholder reaches age 70½; and by certain other 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 or 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) 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 Columbia Acorn Funds have adopted, a distribution plan that sets the distribution and/or service fees that are periodically deducted from the Funds’ 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 of the Columbia Acorn Funds.

	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

The distribution and/or service fees for Class A, Class B, Class C and Class R shares may be 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.

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Choosing a Share Class (continued)

If you maintain shares of the Fund directly with the Fund, without working directly with a financial advisor or other 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 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 plan continues 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 0.40% 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, the Investment Manager and their affiliates make payments with respect to a Fund or the Columbia Funds generally on a basis other than those described above or in larger amounts 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, maintenance of shareholder records, preparation of account statements and provision of 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, effective May 1, 2013, each Fund in the Columbia Acorn Family of Funds compensates the Transfer Agent for payments made for Shareholder Services in an amount equal to: (i) 0.18% of the average aggregate value of the Fund's shares attributable to retirement plan sponsors, deferred contribution plans, 529 plans (together, Plans) or other selling agents that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders in the Plans (including retirement plan accounts maintained by certain mutual fund trading platforms (also known as “fund supermarkets”)); or (ii) an annual fee of $14.00 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by a fund supermarket, broker-dealer firm or other selling agents not covered by clause (i), provided that total combined Transfer Agent fees and payments for Shareholder Services for Class R5 shares are subject to an annual cap of 0.05% of the average daily net assets of the class. The Transfer Agent does not pay selling agents for Shareholder Services, and the Fund does not compensate the Transfer Agent for any Shareholder Services provided by selling agents, with respect to Class I and Class Y shares of the Columbia Acorn Funds. Payments to selling agents in excess of that paid by the Fund are borne by the Distributor, the Investment Manager and/or their affiliates.

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

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

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

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

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 security will be valued in good faith based on a determination of the security's fair value pursuant to the Portfolio Pricing Policy approved by the Board. The Portfolio Pricing Policy provides that fair value determinations will be made using the methodology set forth in the Policy and deemed most appropriate under the circumstances and considering all available, relevant factors and indications of value. The Portfolio Pricing Policy provides that fair valuation may be used 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. In addition, in the event of a significant movement in the Standard & Poor's 500 E-Mini Index, a statistical fair valuation process is applied to adjust prices of foreign securities traded on foreign exchanges in time zones different from the United States utilizing the services of a designated pricing vendor. 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. Please consult the SAI for more information on the factors to be considered in making fair value determinations; the significant events that may necessitate fair valuation of foreign securities; and the Fund's statistical fair valuation methodology.

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Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

When fair valuation is used to price securities, the values for those securities may be higher or lower than values used by another fund to price 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.

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 for amounts greater than $100,000 and other transactions, as described below, 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

The Transfer Agent may require a Medallion Signature Guarantee for your signature in order to process certain transactions. A Medallion Signature Guarantee helps assure that a signature is genuine and not a forgery. A Medallion Signature Guarantee must be provided by an eligible guarantor institution including, but not limited to, the following: a bank, credit union, savings association, broker or dealer that participates in the Securities Transfer Association Medallion Program (STAMP), the Stock Exchange Medallion Program (SEMP) or the New York Stock Exchange Medallion Signature Program (MSP). Notarization by a notary public is not an acceptable signature guarantee. The Transfer Agent reserves the right to reject a signature guarantee and to request additional documentation for any transaction.

A Medallion Signature Guarantee is required if: (i) the transaction amount is over $100,000; (ii) you want your check made payable to someone other than the registered account owner(s); (iii) the address of record has changed within the last 30 days; (iv) you want the check mailed to an address other than the address of record; (v) you want proceeds to be sent according to existing bank account instructions not coded for outgoing Automated Clearing House (ACH) or wire, or to a bank account not on file; (vi) you are the beneficiary of the account and the account owner is deceased (other documentation may be required); or (vii) you are changing legal ownership of your account.

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

38	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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 purchase 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 purchase or exchange order even if the transaction is not subject to the specific 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 purchase 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 purchase orders, including exchange purchase 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 in 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 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 and Procedures.

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 or 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

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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

40	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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 or 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 these selling agents to carry out their obligations to its customers.

The Fund may engage selling agents to receive purchase, exchange and sell 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 columbiathreadneedle.com/us 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. 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.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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 of redemption proceeds 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 Fund shares 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 Automated Clearing House (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 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.

42	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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 an electronic fund transfer, 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

Fund Closed to Most New Investors and New Accounts

The Fund is closed to most new investors and new accounts effective as of the Closing Date, subject to the following limited exceptions:

■	Shareholders who had opened and funded an account with the Fund as of the Closing Date may continue to make additional purchases of Fund shares in their existing accounts, subject to the eligibility requirements of the Fund’s various share classes.

■

A retirement plan generally may continue to make additional purchases of Fund shares and to add new accounts that may purchase Fund shares if the retirement plan or a retirement plan with the same or an affiliated plan sponsor holding Fund shares at the plan level had invested in the Fund as of the Closing Date, subject to the eligibility requirements of the Fund’s various share classes. A retirement plan that has approved the Fund as an investment option as of the Closing Date may open an account and make purchases of Fund shares and add new accounts, even if the retirement plan had not opened an account as of the Closing Date, provided that it opened its initial account with the Fund prior to October 9, 2014.

■	A discretionary wrap program or similar advisory program that holds Fund shares as of the Closing Date generally may continue to make additional purchases of Fund shares and add new accounts that may purchase Fund shares, subject to the eligibility requirements of the Fund’s various share classes.

■	A discretionary wrap program and discretionary model retirement asset allocation program that follows an asset allocation model that included the Fund as an investment option as of the Closing Date may open an account and make additional purchases of Fund shares and add new accounts.

■

A Columbia Management state tuition plan organized under Section 529 of the Internal Revenue Code that had accounts that held Fund shares as of the Closing Date may continue to make additional purchases of Fund shares and to add new accounts that may purchase Fund shares, subject to the eligibility requirements of the Fund’s various share classes.

In the event that an order to purchase shares is received by the Fund or the Transfer Agent after the Closing Date from a new investor or a new account that is not eligible to purchase shares, the order will be refused by the Fund or the Transfer Agent and any money that the Fund or the Transfer Agent received with the order will be returned to the investor, account or selling agent, as appropriate, without interest.

The Fund reserves the right to re-open the Fund to new investors or new accounts and to otherwise modify the extent to which sales of Fund shares are limited.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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 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 Columbia Money Market Fund. Please consult your selling agent to understand its 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-funds 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.

44	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

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 for such pre-existing programs and add new shareholders in the program.

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

Class Z shares are available only to the categories of eligible investors described below under Class Z Shares Minimum Initial Investments. Selling agents that clear Fund share transactions through designated selling agents and their mutual fund trading platforms that were given specific written notice from the Transfer Agent of the termination, effective March 29, 2013, 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 have continuously held 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 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 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 so long as the initial Class Z account was funded by July 2, 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 received specific written notice from the Transfer Agent of the termination, effective March 29, 2013, 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). 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.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(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 its 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)

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 amount for systematic investment plan accounts is the same as the amount set forth in the first four rows of the table, as applicable.

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.

■	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.

46	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

■

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 series of Columbia Funds Series Trust or Columbia Funds Series Trust I 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 semiannual 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.

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. The ability to invest distributions from one Fund to another Fund may not be available to accounts held at all selling agents.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

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. 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 account any business day on a monthly, quarterly or semiannual basis. Currently, Systematic Withdrawal Plans are generally available for Class A, Class B, Class C, Class R4, Class R5, Class T, Class W, Class Y and Class Z share accounts. 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. 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.

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 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.

48	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

■

If you sell your shares that are held directly with the Funds (through the Transfer Agent), 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 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 trading thereon is restricted or during emergency or other circumstances, including 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 your 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 Columbia 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 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, as described above in Buying, Selling and Exchanging Shares — Transaction Rules and Policies. 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.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Buying, Selling and Exchanging Shares (continued)

■

If you exchange shares from Class A shares of Columbia 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 Columbia 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 Columbia 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 Columbia 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 Columbia 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.

■

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.

■	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).

50	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

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 generally unrealized. If the fund sells an investment, it generally will realize a capital gain if it sells that investment for a higher price than its adjusted cost basis, and will generally realize a capital loss if it sells that investment for a lower price than its adjusted cost basis. Capital gains and losses are either short-term or long-term, depending on whether the fund holds the securities for one year or less (short-term) or more than one year (long-term).

FUNDamentals

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	semiannually
Distributions	semiannually

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.

For accounts held directly with the Fund (through the Transfer Agent), 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.

52	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Distributions and Taxes (continued)

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.

Taxes

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

■

The Fund intends to qualify and to be eligible for treatment 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 for treatment as a regulated investment company would result in Fund-level taxation, and consequently, a reduction in income available for distribution to you and in the net asset value of your shares. Even if the Fund qualifies for treatment as a regulated investment company, the Fund may be subject to federal excise tax on certain undistributed income or gains.

■

Distributions, if taxable, generally are taxable to you when paid, whether they are paid in cash or automatically reinvested in additional Fund shares. Dividends paid in January are deemed paid on December 31 of the prior year if the dividend was declared and payable to shareholders of record in October, November, or December of such prior year.

■

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.

■

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 the lower net long-term capital gain rates instead of the higher ordinary income 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.

■

Certain high-income individuals (as well as estates and trusts) are subject to a 3.8% tax on net investment income. For individuals, the 3.8% tax applies 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.”

■

Certain derivative instruments when held in the 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 write options, as described further in the SAI. Generally, a Fund realizes a capital gain or loss on an option when the option expires, or when it is exercised, sold or otherwise terminated. However, if an option is a “section 1256 contract,” which includes most traded options on a broad-based index, and the

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Distributions and Taxes (continued)

Fund holds such option at the end of its taxable year, the Fund is deemed to sell such option at fair market value at such time and recognize any gain or loss thereon, which is generally deemed to be 60% long-term and 40% short-term gain or loss, as described further in the SAI.

■

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 your adjusted tax basis in the shares, which is generally 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 generally is required to report to shareholders and the Internal Revenue Service (the IRS) upon the sale, exchange or redemption of Fund shares cost basis information with respect to those shares. The Fund uses average cost basis as its default method of calculating cost basis. Please see columbiathreadneedle.com/us or contact the Fund at 800.345.6611 for more information regarding average cost basis reporting, other available cost basis methods 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 is required by federal law to withhold tax on any taxable or 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 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.

FUNDamentals

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.

54	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Financial Highlights

The financial highlights tables are intended to help you understand the Fund’s financial performance for the past five fiscal years or, if shorter, the Fund’s period of operations. Certain information reflects financial results for a single Fund share. Per share net investment income (loss) amounts are calculated based on average shares outstanding during the period. The total returns in the tables represent the rate that an investor would have earned (or lost) on an investment in the Fund assuming all dividends and distributions had been reinvested. Total return does not reflect payment of sales charges, if any. Total return and portfolio turnover are not annualized for periods of less than one year. The portfolio turnover rate is calculated without regard to purchase and sales transactions of short-term instruments and certain derivatives, if any. If such transactions were included, the Fund’s portfolio turnover rate might be higher. This information has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, whose report, along with the Fund’s financial statements, is included in the Fund’s annual report, which is available upon request. The independent registered public accounting firm’s report and the Fund’s financial statements are also incorporated by reference into the SAI.

Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations		Total from investment operations	Less Distributions to Shareholders	Total Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Total from investment operations	Net investment income	Total Distributions to Shareholders
Class A
Year Ended December 31, 2014	$13.37	0.06	(0.63)	(0.57)	(0.08)	(0.08)
Year Ended December 31, 2013	$12.04	0.07	1.34	1.41	(0.08)	(0.08)
Year Ended December 31, 2012	$9.26	0.08	2.78	2.86	(0.08)	(0.08)
Year Ended December 31, 2011^(d)	$10.00	(0.00) ^(e)	(0.74)	(0.74)	—	—
Class C
Year Ended December 31, 2014	$13.32	(0.05)	(0.62)	(0.67)	—	—
Year Ended December 31, 2013	$12.01	(0.03)	1.34	1.31	—	—
Year Ended December 31, 2012	$9.24	(0.02)	2.79	2.77	—	—
Year Ended December 31, 2011^(h)	$10.00	(0.02)	(0.74)	(0.76)	—	—
Class I
Year Ended December 31, 2014	$13.41	0.06	(0.60)	(0.54)	(0.12)	(0.12)
Year Ended December 31, 2013	$12.08	0.08	1.37	1.45	(0.12)	(0.12)
Year Ended December 31, 2012	$9.29	0.11	2.80	2.91	(0.12)	(0.12)
Year Ended December 31, 2011⁽ⁱ⁾	$10.00	0.01	(0.72)	(0.71)	—	—
Class R4
Year Ended December 31, 2014	$13.49	0.09	(0.63)	(0.54)	(0.12)	(0.12)
Year Ended December 31, 2013	$12.14	0.12	1.35	1.47	(0.12)	(0.12)
Year Ended December 31, 2012^(j)	$11.44	(0.01)	0.81	0.80	(0.10)	(0.10)
Class R5
Year Ended December 31, 2014	$13.48	0.10	(0.64)	(0.54)	(0.12)	(0.12)
Year Ended December 31, 2013	$12.14	0.12	1.34	1.46	(0.12)	(0.12)
Year Ended December 31, 2012^(k)	$11.44	(0.00) ^(e)	0.81	0.81	(0.11)	(0.11)
Class Y
Year Ended December 31, 2014	$13.36	0.09	(0.62)	(0.53)	(0.12)	(0.12)
Year Ended December 31, 2013^(l)	$12.22	0.07	1.20	1.27	(0.13)	(0.13)
Class Z
Year Ended December 31, 2014	$13.40	0.08	(0.63)	(0.55)	(0.11)	(0.11)
Year Ended December 31, 2013	$12.07	0.11	1.33	1.44	(0.11)	(0.11)
Year Ended December 31, 2012	$9.28	0.12	2.79	2.91	(0.12)	(0.12)
Year Ended December 31, 2011^(m)	$10.00	0.01	(0.73)	(0.72)	—	—

Notes to Financial Highlights

(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(b)	Had the Investment Manager and/or its affiliates not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(c)	The benefits derived from custody fees paid indirectly had an impact of 0.01%.

(d)	Class A shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

(e)	Rounds to zero.

(f)	Annualized.

(g)	The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(h)	Class C shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

(i)	Class I shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

(j)	Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(k)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(l)	Class Y shares commenced operations on June 13, 2013. Per share data and total return reflect activity from that date.

(m)	Class Z shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

56	Prospectus 2015

Columbia Acorn Emerging Markets Fund^SM

Financial Highlights (continued)

Net Asset Value, End of Period	Total Return	Ratio to Average Net Assets			Supplemental Data
Net Asset Value, End of Period	Total Return	Total gross expenses	Total net expenses	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

$12.72	(4.28)%	1.56% ^(a)	1.56% ^(a)	0.42%	45%	$160,969
$13.37	11.73% ^(b)	1.80% ^(a)	1.76% ^(a)	0.52%	36%	$177,158
$12.04	30.86% ^(b)	6.42% ^(a)	1.77% ^(a)(c)	0.77%	30%	$3,103
$9.26	(7.40)% ^(b)	20.13% ^(f)	1.85% ^(f)(g)	(0.01)% ^(f)	9%	$332

$12.65	(5.03)%	2.33% ^(a)	2.33% ^(a)	(0.36)%	45%	$41,208
$13.32	10.91% ^(b)	2.55% ^(a)	2.51% ^(a)	(0.23)%	36%	$32,636
$12.01	29.98% ^(b)	7.18% ^(a)	2.56% ^(a)(c)	(0.15)%	30%	$615
$9.24	(7.60)% ^(b)	25.06% ^(f)	2.60% ^(f)(g)	(0.68)% ^(f)	9%	$127

$12.75	(4.01)%	1.22% ^(a)	1.22% ^(a)	0.44%	45%	$3
$13.41	12.06% ^(b)	1.73% ^(a)	1.39% ^(a)	0.65%	36%	$7
$12.08	31.39% ^(b)	6.18% ^(a)	1.41% ^(a)(c)	1.05%	30%	$6
$9.29	(7.10)% ^(b)	19.31% ^(f)	1.41% ^(f)(g)	0.17% ^(f)	9%	$5

$12.83	(4.03)%	1.28% ^(a)	1.28% ^(a)	0.66%	45%	$15,467
$13.49	12.13% ^(b)	1.44% ^(a)	1.44% ^(a)	0.92%	36%	$13,583
$12.14	7.04% ^(b)	5.86% ^(a)(f)	1.54% ^(a)(c)(f)	(0.31)% ^(f)	30%	$16

$12.82	(4.02)%	1.26% ^(a)	1.26% ^(a)	0.72%	45%	$19,632
$13.48	12.07% ^(b)	1.42% ^(a)	1.42% ^(a)	0.94%	36%	$13,625
$12.14	7.11% ^(b)	5.81% ^(a)(f)	1.46% ^(a)(c)(f)	(0.22)% ^(f)	30%	$3

$12.71	(3.95)%	1.22% ^(a)	1.22% ^(a)	0.68%	45%	$2
$13.36	10.43% ^(b)	1.36% ^(a)(f)	1.36% ^(a)(f)	0.97% ^(f)	36%	$3

$12.74	(4.12)%	1.33% ^(a)	1.33% ^(a)	0.62%	45%	$245,053
$13.40	11.92% ^(b)	1.58% ^(a)	1.54% ^(a)	0.89%	36%	$177,693
$12.07	31.35% ^(b)	6.15% ^(a)	1.46% ^(a)(c)	1.07%	30%	$6,846
$9.28	(7.20)% ^(b)	19.52% ^(f)	1.46% ^(f)(g)	0.15% ^(f)	9%	$2,765

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

Additional information about the Fund’s investments is available in the Fund’s annual and semiannual 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. The SAI also provides additional information about the Fund and its policies. The SAI, which has been filed with the SEC, is legally part of this prospectus (incorporated by reference). To obtain these documents free of charge, to request other information about the Fund and to make shareholder inquiries, please contact the Fund as follows:

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: columbiathreadneedle.com/us

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.

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, D.C. 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, D.C. 20549-1520.

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

PRO108_12_E01_(05/15)

Columbia Acorn European Fund^SM

Summary of the Fund

Investment Objective

Columbia Acorn European Fund^SM (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 22 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class C	Classes I, R4, R5 and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	1.00% ^(b)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class C	Class I	Class R4	Class R5	Class Z
Management fees	1.19%	1.19%	1.19%	1.19%	1.19%	1.19%
Distribution and/or service (12b-1) fees	0.25%	1.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.61%	0.63%	0.50%	0.62%	0.55%	0.60%
Total annual Fund operating expenses	2.05%	2.82%	1.69%	1.81%	1.74%	1.79%
Fee waivers and/or expense reimbursements^(c)	(0.30%)	(0.32%)	(0.28%)	(0.31%)	(0.28%)	(0.29%)
Total annual Fund operating expenses after fee waivers and/or expense reimbursements	1.75%	2.50%	1.41%	1.50%	1.46%	1.50%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.
(b)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

(c)

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 transaction costs and certain other investment-related expenses, 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% for Class A shares, 2.50% for Class C shares, 1.41% for Class I shares, 1.50% for Class R4 shares, 1.46% for Class R5 shares and 1.50% for Class Z shares, through April 30, 2016.This arrangement may only be modified or amended with approval from all parties to the arrangement, including the Fund and the Investment Manager.

Example

■	you invest $10,000 in the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn European Fund^SM

Summary of the Fund (continued)

Since the waivers and/or reimbursements shown in the Annual Fund Operating Expenses table above expire as indicated in the preceding table, they are only reflected in the 1 year example and the first year of the other examples. Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$743	1,153	$1,589	$2,795
Class C (assuming redemption of all shares at the end of the period)	$353	844	$1,461	$3,124
Class C (assuming no redemption of shares)	$253	844	$1,461	$3,124
Class I (whether or not shares are redeemed)	$144	505	$ 892	$1,974
Class R4 (whether or not shares are redeemed)	$153	539	$ 951	$2,101
Class R5 (whether or not shares are redeemed)	$149	521	$ 918	$2,029
Class Z (whether or not shares are redeemed)	$153	535	$ 943	$2,081

Portfolio Turnover

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 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.

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

4	Prospectus 2015

Columbia Acorn European Fund^SM

Summary of the Fund (continued)

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Geographic Concentration Risk/Europe Risk. The Fund may be particularly susceptible to economic, political, regulatory or other events or conditions affecting issuers and countries in Europe. Currency devaluations could occur in countries that have not yet experienced currency devaluation to date, or could continue to occur in countries that have already experienced such devaluations. In addition, the private and public sectors’ debt problems of a single European Union (EU) country can pose significant economic risks to the EU as a whole. As a result, the Fund’s NAV may be more volatile than the NAV of a more geographically diversified fund. If securities of issuers in Europe fall out of favor, it may cause the Fund to underperform other funds that do not concentrate in this region of the world.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less

Prospectus 2015

Columbia Acorn European Fund^SM

Summary of the Fund (continued)

developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

6	Prospectus 2015

Columbia Acorn European Fund^SM

Summary of the Fund (continued)

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

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. The bar chart shows how the Fund’s Class Z share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with the Standard & Poor’s (S&P) Europe Between $500 Million and $5 Billion^® Index, the Fund's primary benchmark, and the Euromoney Smaller European Companies (inc. UK) Index. The S&P Europe Between $500 Million and $5 Billion^® Index is representative of the institutionally investable capital of 17 European countries (as of December 31, 2014), as determined by S&P, with market caps ranging between $500 million to $5 billion. The Euromoney Smaller European Companies (inc. UK) Index is an index of smaller companies in Europe including the UK market. The Euromoney Smaller European Companies Index covers companies of small- and mid-cap market capitalization in Europe's developed markets. The index is rebalanced on a quarterly basis. The performance of the Euromoney Smaller European Companies (inc UK) Index is provided to show how the Fund’s performance compares to a widely recognized index of small-capitalization equity performance in European markets.

The after-tax returns shown in the Average Annual Total Returns table below 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). The after-tax returns are shown only for Class Z shares and will vary for other share classes. 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.

Prospectus 2015

Columbia Acorn European Fund^SM

Summary of the Fund (continued)

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{1st Quarter 2012}	_17.69%
	_Worst	_{3rd Quarter 2014}	_-9.07%

*	Year to Date return as of March 31, 2015: 4.39%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	Life of Fund
Class Z	08/19/2011
returns before taxes		-7.52%	12.40%
returns after taxes on distributions		-7.59%	12.27%
returns after taxes on distributions and sale of Fund shares		-3.86%	9.86%
Class A returns before taxes	08/19/2011	-13.09%	10.15%
Class C returns before taxes	08/19/2011	-9.35%	11.28%
Class I returns before taxes	08/19/2011	-7.49%	12.43%
Class R4 returns before taxes	06/25/2014	-7.49%	12.41%
Class R5 returns before taxes	11/08/2012	-7.54%	12.39%
S&P Europe Between $500 Million and $5 Billion^® Index (reflects no deductions for fees, expenses or taxes)		-5.35%	13.80%
Euromoney Smaller European Companies (inc UK) Index (reflects no deductions for fees, expenses or taxes)		-7.67%	11.72%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Andreas Waldburg-Wolfegg	Portfolio Manager and Analyst	Co-manager or lead manager since inception in 2011	2011
Stephen Kusmierczak, CFA	Portfolio Manager and Analyst	Co-manager since inception in 2011	2011

8	Prospectus 2015

Columbia Acorn European Fund^SM

Summary of the Fund (continued)

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A & C	All accounts other than IRAs	$2,000	$100
Classes A & C	IRAs	$1,000	$100
Classes I & R4	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

There is no minimum additional investment for any share class.

Tax Information

Payments to Broker-Dealers and Other Financial Intermediaries

Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund

Investment Objective

Columbia Acorn European Fund^SM (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

10	Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

Geographic Concentration Risk/Europe Risk. The Fund may be particularly susceptible to economic, political, regulatory or other events or conditions affecting issuers and countries in Europe. Most developed countries in Western Europe are members of the European Union (EU), and many are also members of the European Economic and Monetary Union (EMU). European countries can be significantly affected by the tight fiscal and monetary controls that the EMU imposes on its members and with which candidates for EMU membership are required to comply. In addition, the private and public sectors’ debt problems of a single EU country can pose significant economic risks to the EU as a whole. Unemployment in Europe has historically been higher than in the United States and public deficits are an ongoing concern in many European countries. Currency devaluations could occur in countries that have not yet experienced currency devaluation to date, or could continue to occur in countries that have already experienced such

Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

devaluations. As a result, the Fund’s NAV may be more volatile than the NAV of a more geographically diversified fund. If securities of issuers in Europe fall out of favor, it may cause the Fund to underperform other funds that do not concentrate in this region of the world.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar. Foreign securities may also be less liquid than securities of U.S. companies so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

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.

12	Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries.

Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Investment Guidelines

14	Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

Holding Other Kinds of Investments

Transactions in Derivatives

Investing in Affiliated Funds

Investing in Money Market Funds

Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

Lending of Portfolio Securities

Investing Defensively

Portfolio Holdings Disclosure

Cybersecurity

Use of Benchmarks

16	Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Additional Information on Portfolio Turnover

Cash Flows

Understanding Annual Fund Operating Expenses

Prospectus 2015

Columbia Acorn European Fund^SM

More Information About the Fund (continued)

FUNDamentals

Other Expenses

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

Columbia Acorn European Fund
Class A	1.75%
Class C	2.50%
Class I	1.41%
Class R4	1.50%
Class R5	1.46%
Class Z	1.50%

Board of Trustees

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More Information About the Fund (continued)

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

Primary Service Providers

The Investment Manager

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 approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Portfolio Managers

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Andreas Waldburg-Wolfegg	Portfolio Manager and Analyst	Co-manager or lead manager since inception in 2011	2011
Stephen Kusmierczak, CFA	Portfolio Manager and Analyst	Co-manager since inception in 2011	2011

Mr. Waldburg-Wolfegg has been associated with the Investment Manager or its predecessors as an investment professional since 2002 and has been a 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.

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More Information About the Fund (continued)

The Administrator

Annual Administration Fee, as a % of Aggregate 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

The Transfer Agent

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

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More Information About the Fund (continued)

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

■

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

■

Certain Legal Matters

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Columbia Acorn European Fund^SM

Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

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Choosing a Share Class (continued)

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.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

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Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

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Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

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Choosing a Share Class (continued)

classes do not have a front-end sales charge, so the full amount of your purchase price is invested in those classes. Class A shares have lower ongoing distribution and/or service 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 and service fees that are equal to or more than the front-end sales charge and the distribution and service fees you would pay for Class A shares. Thus, although the full amount of your purchase price of Class B, Class C and Class R shares is invested in a Fund, your return on this money will be reduced by the expected higher annual expenses of Class B, 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 and/or service fees.

Class A Shares — Front-End Sales Charge

FUNDamentals

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 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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Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

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Choosing a Share Class (continued)

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

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Choosing a Share Class (continued)

Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

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Choosing a Share Class (continued)

Class K, Class R and Class Y shares of the Funds, Class R4 and Class R5 shares of the Funds held in retirement plan accounts and direct purchases of Columbia Money Market Fund shares, which may not be aggregated. Shares of Columbia Money Market Fund acquired by exchange from other Funds may be combined for ROA 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.

FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

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Choosing a Share Class (continued)

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.

Front-End Sales Charge Waivers

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 70½; and by certain other 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 or Class C shares, see Appendix S to the SAI.

Repurchases

Restrictions and Changes in Terms and Conditions

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Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

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Choosing a Share Class (continued)

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 pay 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 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

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

Business Days

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Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

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Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

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Buying, Selling and Exchanging Shares (continued)

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.

Opening an Account and Placing Orders

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Buying, Selling and Exchanging Shares (continued)

Accounts Established Directly with the Fund

Written Transactions

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Buying, Selling and Exchanging Shares (continued)

Telephone Transactions

Online Transactions

Wire Transactions

Electronic Funds Transfer

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Buying, Selling and Exchanging Shares (continued)

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

Class R Shares

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Buying, Selling and Exchanging Shares (continued)

Class R4 Shares

Class R4 shares of the Fund are not expected to be available for purchase until June 25, 2014.

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

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Buying, Selling and Exchanging Shares (continued)

make additional purchases of Class Z shares (other than through reinvestment of distributions). 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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

Class Z Shares Minimum Initial Investments

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

■

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

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Buying, Selling and Exchanging Shares (continued)

■

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

■	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.

■

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

■

■	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.

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Buying, Selling and Exchanging Shares (continued)

Systematic Investment Plan

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

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Buying, Selling and Exchanging Shares (continued)

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

Systematic Exchanges

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Buying, Selling and Exchanging Shares (continued)

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

■

■	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 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).

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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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

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Distributions and Taxes (continued)

Taxes

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

■

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Distributions and Taxes (continued)

■

FUNDamentals

Taxes

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Financial Highlights

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Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations		Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$15.68	0.13	(1.34)	(1.21)	(0.05)	(0.08)
Year Ended December 31, 2013	$11.76	(0.02)	3.97	3.95	(0.01)	(0.02)
Year Ended December 31, 2012	$9.43	0.03	2.37	2.40	(0.07)	(0.00) ^(c)
Year Ended December 31, 2011^(e)	$10.00	(0.03)	(0.46)	(0.49)	(0.06)	(0.02)
Class C
Year Ended December 31, 2014	$15.54	(0.01)	(1.29)	(1.30)	—	(0.08)
Year Ended December 31, 2013	$11.73	(0.15)	3.98	3.83	—	(0.02)
Year Ended December 31, 2012	$9.44	(0.15)	2.46	2.31	(0.02)	(0.00) ^(c)
Year Ended December 31, 2011^(h)	$10.00	(0.06)	(0.45)	(0.51)	(0.03)	(0.02)
Class I
Year Ended December 31, 2014	$15.67	0.11	(1.27)	(1.16)	(0.10)	(0.08)
Year Ended December 31, 2013	$11.75	0.12	3.88	4.00	(0.06)	(0.02)
Year Ended December 31, 2012	$9.43	0.10	2.32	2.42	(0.10)	(0.00) ^(c)
Year Ended December 31, 2011⁽ⁱ⁾	$10.00	(0.02)	(0.46)	(0.48)	(0.07)	(0.02)
Class R4
Year Ended December 31, 2014^(j)	$15.85	(0.02)	(1.34)	(1.36)	(0.09)	—
Class R5
Year Ended December 31, 2014	$15.82	0.14	(1.32)	(1.18)	(0.09)	(0.08)
Year Ended December 31, 2013	$11.86	(0.04)	4.06	4.02	(0.04)	(0.02)
Year Ended December 31, 2012^(k)	$11.19	(0.02)	0.77	0.75	(0.08)	—
Class Z
Year Ended December 31, 2014	$15.68	0.15	(1.32)	(1.17)	(0.09)	(0.08)
Year Ended December 31, 2013	$11.76	0.11	3.88	3.99	(0.05)	(0.02)
Year Ended December 31, 2012	$9.44	0.08	2.34	2.42	(0.10)	(0.00) ^(c)
Year Ended December 31, 2011(l)	$10.00	(0.02)	(0.46)	(0.48)	(0.06)	(0.02)

Notes to Financial Highlights

(a)	Had the Investment Manager and/or its affiliates not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(b)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(c)	Rounds to zero.

(d)	The benefits derived from custody fees paid indirectly had an impact of 0.01%.

(e)	Class A shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

(f)	Annualized.

(g)	The benefits derived from custody fees paid indirectly had an impact of 0.02%.

(h)	Class C shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

(i)	Class I shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

(j)	Class R4 shares commenced operations on June 25, 2014. Per share data and total return reflect activity from that date.

(k)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(l)	Class Z shares commenced operations on August 19, 2011. Per share data and total return reflect activity from that date.

52	Prospectus 2015

Columbia Acorn European Fund^SM

Financial Highlights (continued)

Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return ^(a)	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return ^(a)	Total gross expenses	Total net expenses	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

(0.13)	$14.34	(7.77)%	2.05% ^(b)	1.75% ^(b)	0.86%	74%	$21,101
(0.03)	$15.68	33.64%	3.33% ^(b)	1.74% ^(b)	(0.11)%	42%	$19,078
(0.07)	$11.76	25.46%	12.35% ^(b)	1.61% ^(b)(d)	0.23%	37%	$453
(0.08)	$9.43	(4.97)%	33.59% ^(f)	1.75% ^(f)(g)	(0.84)% ^(f)	17%	$154

(0.08)	$14.16	(8.44)%	2.84% ^(b)	2.50% ^(b)	(0.10)%	74%	$5,096
(0.02)	$15.54	32.63%	4.19% ^(b)	2.50% ^(b)	(1.10)%	42%	$1,400
(0.02)	$11.73	24.46%	12.83% ^(b)	2.32% ^(b)(d)	(1.33)%	37%	$89
(0.05)	$9.44	(5.14)%	35.79% ^(f)	2.50% ^(f)(g)	(1.66)% ^(f)	17%	$5

(0.18)	$14.33	(7.49)%	1.71% ^(b)	1.46% ^(b)	0.74%	74%	$2
(0.08)	$15.67	34.06%	3.99% ^(b)	1.41% ^(b)	0.88%	42%	$8
(0.10)	$11.75	25.71%	12.05% ^(b)	1.31% ^(b)(d)	0.94%	37%	$6
(0.09)	$9.43	(4.81)%	30.00% ^(f)	1.31% ^(f)(g)	(0.47)% ^(f)	17%	$5

(0.09)	$14.40	(8.60)%	1.87% ^(b)(f)	1.50% ^(b)(f)	(0.30)% ^(f)	74%	$302

(0.17)	$14.47	(7.54)%	1.75% ^(b)	1.52% ^(b)	0.92%	74%	$1,633
(0.06)	$15.82	33.97%	2.76% ^(b)	1.51% ^(b)	(0.29)%	42%	$1,891
(0.08)	$11.86	6.70%	14.07% ^(b)(f)	1.36% ^(b)(d)(f)	(1.07)% ^(f)	37%	$3

(0.17)	$14.34	(7.52)%	1.79% ^(b)	1.50% ^(b)	0.97%	74%	$8,499
(0.07)	$15.68	33.98%	3.98% ^(b)	1.45% ^(b)	0.83%	42%	$4,407
(0.10)	$11.76	25.66%	12.07% ^(b)	1.33% ^(b)(d)	0.76%	37%	$2,727
(0.08)	$9.44	(4.78)%	30.26% ^(f)	1.37% ^(f)(g)	(0.52)% ^(f)	17%	$1,516

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO109_12_E01_(05/15)

Columbia Acorn® Fund

Summary of the Fund

Investment Objective

Columbia Acorn^® Fund (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 21 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class B	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	5.00% ^(b)	1.00% ^(c)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class B	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees	0.64%	0.64%	0.64%	0.64%	0.64%	0.64%	0.64%	0.64%
Distribution and/or service (12b-1) fees	0.25%	0.75%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.19%	0.37%	0.14%	0.07%	0.20%	0.12%	0.07%	0.15%
Total annual Fund operating expenses	1.08%	1.76%	1.78%	0.71%	0.84%	0.76%	0.71%	0.79%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

(b)	This charge decreases over time.

(c)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

Example

■	you invest $10,000 in the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn® Fund

Summary of the Fund (continued)

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$679	$899	$1,136	$1,816
Class B (assuming redemption of all shares at the end of the period)	$679	$854	$1,154	$1,894
Class B (assuming no redemption of shares)	$179	$554	$ 954	$1,894
Class C (assuming redemption of all shares at the end of the period)	$281	$560	$ 964	$2,095
Class C (assuming no redemption of shares)	$181	$560	$ 964	$2,095
Class I (whether or not shares are redeemed)	$ 73	$227	$ 395	$ 883
Class R4 (whether or not shares are redeemed)	$ 86	$268	$ 466	$1,037
Class R5 (whether or not shares are redeemed)	$ 78	$243	$ 422	$ 942
Class Y (whether or not shares are redeemed)	$ 73	$227	$ 395	$ 883
Class Z (whether or not shares are redeemed)	$ 81	$252	$ 439	$ 978

Portfolio Turnover

Principal Investment Strategies

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 in which the company has a competitive advantage.

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

4	Prospectus 2015

Columbia Acorn® Fund

Summary of the Fund (continued)

Principal Risks

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

Prospectus 2015

Columbia Acorn® Fund

Summary of the Fund (continued)

example, from rapid changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries, and some have a higher risk of currency devaluations.

6	Prospectus 2015

Columbia Acorn® Fund

Summary of the Fund (continued)

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. The bar chart shows how the Fund’s Class Z share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown with those of the Russell 2500 Index, the Fund’s primary benchmark, the Russell 2000 Index and the Standard & Poor’s (S&P) 500^® 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 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 index of companies with somewhat lower capitalization than the Fund’s primary benchmark. 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 broad-based market index.

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{2nd Quarter 2009}	_20.90%
	_Worst	_{4th Quarter 2008}	_-25.11%

*	Year to Date return as of March 31, 2015: 3.97%

Prospectus 2015

Columbia Acorn® Fund

Summary of the Fund (continued)

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class Z	06/10/1970
returns before taxes		0.82%	13.35%	8.39%
returns after taxes on distributions		-2.85%	11.70%	7.21%
returns after taxes on distributions and sale of Fund shares		3.43%	10.77%	6.90%
Class A returns before taxes	10/16/2000	-5.23%	11.69%	7.44%
Class B returns before taxes	10/16/2000	-4.27%	12.08%	7.41%
Class C returns before taxes	10/16/2000	-0.98%	12.18%	7.25%
Class I returns before taxes	09/27/2010	0.91%	13.41%	8.42%
Class R4 returns before taxes	11/08/2012	0.81%	13.33%	8.38%
Class R5 returns before taxes	11/08/2012	0.89%	13.37%	8.40%
Class Y returns before taxes	11/08/2012	0.94%	13.39%	8.41%
Russell 2500 Index (reflects no deductions for fees, expenses or taxes)		7.07%	16.36%	8.72%
Russell 2000 Index (reflects no deductions for fees, expenses or taxes)		4.89%	15.55%	7.77%
S&P 500^® Index (reflects no deductions for fees, expenses or taxes)		13.69%	15.45%	7.67%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Robert A. Mohn, CFA	Portfolio Manager, Analyst and Domestic Chief Investment Officer of the Investment Manager	Co-manager or lead manager since 2003	1992
P. Zachary Egan, CFA	President, International Chief Investment Officer, Portfolio Manager and Analyst of the Investment Manager	Co-manager since 2015	1999
Fritz Kaegi, CFA	Portfolio Manager and Analyst	Co-manager since 2015	2004
David L. Frank, CFA	Portfolio Manager and Analyst	Co-manager since 2014	2002

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

8	Prospectus 2015

Columbia Acorn® Fund

Summary of the Fund (continued)

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A, B* & C	All accounts other than IRAs	$2,000	$100
Classes A, B* & C	IRAs	$1,000	$100
Classes I, R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

*	Class B shares are generally closed to new and existing shareholders.

There is no minimum additional investment for any share class.

Tax Information

Payments to Broker-Dealers and Other Financial Intermediaries

Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund

Investment Objective

Columbia Acorn^® Fund (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

10	Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

those positions, particularly in a distressed market, could be prolonged and result in losses to the Fund. In addition, some small- and mid-cap companies may not be widely followed by the investment community, which can lower the demand for their stocks.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar. Foreign securities may also be less liquid than securities of U.S. companies so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

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

Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

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.

Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries.

12	Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

Liquidity and Trading Volume Risk. Because the Fund may invest a percentage of its assets in foreign securities, it may be subject to the liquidity and trading volume risks associated with international investing. Due to market conditions, including uncertainty regarding the price of a security, it may be difficult for the Fund to buy or sell foreign portfolio securities at a desirable time or price, which could result in investment losses. This risk of portfolio illiquidity is heightened with respect to small- and mid-cap securities, generally, and foreign small- and mid-cap securities in particular. The Fund may have to lower the selling price, liquidate other investments, or forego another, more appealing investment opportunity as a result of illiquidity in the markets. The Investment Manager will fair value in good faith any securities it deems to be illiquid under consistently applied procedures established by the Fund’s Board. Market conditions are always changing and vary by country and industry sector, and investing in international markets involves unique risks. In the wake of the 2007-2009 financial crisis, trading volumes in both emerging and developed international markets declined significantly and have stayed at generally reduced levels since then. Although it is difficult to accurately assess trends in trading volumes in foreign markets, because some amount of activity has migrated to alternative trading venues, a reduction in trading volumes poses challenges to the Fund. This is particularly so because the Fund focuses on small- and mid-cap companies that usually have lower trading volumes and often takes sizeable positions in portfolio companies. As a result of lower trading volumes, it may take longer to buy or sell these securities, which can exacerbate the Fund’s exposure to volatile markets. The Fund may also be limited in its ability to execute favorable trades in foreign portfolio securities in response to changes in share prices and fundamentals. If the Fund is forced to sell securities to meet redemption requests or other cash needs, or in the case of an event affecting liquidity in a particular market or markets, it may be forced to dispose of those securities under disadvantageous circumstances and at a loss. As the Fund grows in size, these considerations take on increasing significance and may adversely impact performance.

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

Investment Guidelines

Holding Other Kinds of Investments

Investing in Affiliated Funds

Investing in Money Market Funds

14	Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

Lending of Portfolio Securities

Investing Defensively

Portfolio Holdings Disclosure

Cybersecurity

Use of Benchmarks

Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Additional Information on Portfolio Turnover

Cash Flows

Understanding Annual Fund Operating Expenses

16	Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

FUNDamentals

Other Expenses

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates and any predecessor firms that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

Board of 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 February 27, 2015. 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

Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

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 approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Portfolio Managers

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Robert A. Mohn, CFA	Portfolio Manager, Analyst and Domestic Chief Investment Officer of the Investment Manager	Co-manager or lead manager since 2003	1992
P. Zachary Egan, CFA	President, International Chief Investment Officer, Portfolio Manager and Analyst of the Investment Manager	Co-manager since 2015	1999
Fritz Kaegi, CFA	Portfolio Manager and Analyst	Co-manager since 2015	2004
David L. Frank, CFA	Portfolio Manager and Analyst	Co-manager since 2014	2002

Mr. Mohn has been associated with the Investment Manager or its predecessors as an investment professional since 1992 and has been a 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.

Mr. Egan is President and International Chief Investment Officer of the Investment Manager and has been associated with the Investment Manager or its predecessors as an investment professional since 1999. He has been President of the Trust since April 2014 and served as a Vice President of the Trust from 2003 through March 2014. 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.

Mr. Frank has been associated with the Investment Manager or its predecessors since 2002 and has been a Vice President of the Trust since 2014. Mr. Frank began his investment career in 1998 and earned a B.A. from Yale University and an M.B.A. from the University of Chicago.

The Administrator

18	Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

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 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

The Transfer Agent

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

Prospectus 2015

Columbia Acorn® Fund

More Information About the Fund (continued)

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

■

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

■

Certain Legal Matters

20	Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

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.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

22	Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

24	Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge

FUNDamentals

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 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).

Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

26	Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

28	Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Front-End Sales Charge Waivers

CDSC Waivers

Repurchases

Restrictions and Changes in Terms and Conditions

30	Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

Prospectus 2015

Columbia Acorn® Fund

Choosing a Share Class (continued)

32	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares

Share Price Determination

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

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

Business Days

Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

34	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

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.

Opening an Account and Placing Orders

36	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Accounts Established Directly with the Fund

Written Transactions

Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Telephone Transactions

Online Transactions

Wire Transactions

Electronic Funds Transfer

38	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

Class R Shares

Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Class R4 Shares

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

40	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

Class Z Shares Minimum Initial Investments

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

■

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

■

Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

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

■	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.

■

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

■

■	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.

42	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

Systematic Investment Plan

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

Systematic Exchanges

44	Prospectus 2015

Columbia Acorn® Fund

Buying, Selling and Exchanging Shares (continued)

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

■

■	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 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).

Prospectus 2015

Columbia Acorn® Fund

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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

Prospectus 2015

Columbia Acorn® Fund

Distributions and Taxes (continued)

Taxes

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

■

48	Prospectus 2015

Columbia Acorn® Fund

Distributions and Taxes (continued)

■

FUNDamentals

Taxes

Prospectus 2015

Columbia Acorn® Fund

Financial Highlights

Prospectus 2015

Columbia Acorn® Fund

Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations		Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$35.78	(0.08)	0.21	0.13	—	(5.61)
Year Ended December 31, 2013	$29.36	(0.06)	8.84	8.78	(0.04)	(2.32)
Year Ended December 31, 2012	$26.63	0.08	4.53	4.61	(0.06)	(1.82)
Year Ended December 31, 2011	$29.24	(0.10)	(1.30)	(1.40)	(0.02)	(1.19)
Year Ended December 31, 2010	$23.98	(0.06)	6.18	6.12	(0.02)	(0.84)
Class B
Year Ended December 31, 2014	$32.25	(0.29)	0.18	(0.11)	—	(5.61)
Year Ended December 31, 2013	$26.80	(0.25)	8.02	7.77	—	(2.32)
Year Ended December 31, 2012	$24.53	(0.11)	4.20	4.09	—	(1.82)
Year Ended December 31, 2011	$27.14	(0.27)	(1.15)	(1.42)	—	(1.19)
Year Ended December 31, 2010	$22.43	(0.21)	5.76	5.55	—	(0.84)
Class C
Year Ended December 31, 2014	$31.64	(0.28)	0.17	(0.11)	—	(5.61)
Year Ended December 31, 2013	$26.34	(0.26)	7.88	7.62	—	(2.32)
Year Ended December 31, 2012	$24.18	(0.12)	4.10	3.98	—	(1.82)
Year Ended December 31, 2011	$26.85	(0.29)	(1.19)	(1.48)	—	(1.19)
Year Ended December 31, 2010	$22.23	(0.24)	5.70	5.46	—	(0.84)
Class I
Year Ended December 31, 2014	$37.37	0.05	0.22	0.27	—	(5.61)
Year Ended December 31, 2013	$30.47	0.06	9.20	9.26	(0.04)	(2.32)
Year Ended December 31, 2012	$27.57	0.26	4.62	4.88	(0.16)	(1.82)
Year Ended December 31, 2011	$30.19	0.01	(1.35)	(1.34)	(0.09)	(1.19)
Year Ended December 31, 2010^(d)	$26.80	(0.01)	4.26	4.25	(0.02)	(0.84)
Class R4
Year Ended December 31, 2014	$37.88	0.02	0.22	0.24	—	(5.61)
Year Ended December 31, 2013	$30.90	0.06	9.29	9.35	(0.05)	(2.32)
Year Ended December 31, 2012^(f)	$30.59	0.05	1.84	1.89	(0.12)	(1.46)
Class R5
Year Ended December 31, 2014	$37.89	0.04	0.23	0.27	—	(5.61)
Year Ended December 31, 2013	$30.88	0.07	9.30	9.37	(0.04)	(2.32)
Year Ended December 31, 2012^(g)	$30.59	0.06	1.83	1.89	(0.14)	(1.46)
Class Y
Year Ended December 31, 2014	$37.93	0.05	0.24	0.29	—	(5.61)
Year Ended December 31, 2013	$30.90	0.09	9.31	9.40	(0.05)	(2.32)
Year Ended December 31, 2012^(h)	$30.62	0.09	1.80	1.89	(0.15)	(1.46)
Class Z
Year Ended December 31, 2014	$37.32	0.02	0.22	0.24	—	(5.61)
Year Ended December 31, 2013	$30.45	0.04	9.19	9.23	(0.04)	(2.32)
Year Ended December 31, 2012	$27.56	0.17	4.69	4.86	(0.15)	(1.82)
Year Ended December 31, 2011	$30.19	(0.01)	(1.34)	(1.35)	(0.09)	(1.19)
Year Ended December 31, 2010	$24.68	0.02	6.37	6.39	(0.04)	(0.84)

Notes to Financial Highlights

(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(b)	The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(c)	Rounds to zero.

(d)	Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(e)	Annualized.

(f)	Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(g)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(h)	Class Y shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

52	Prospectus 2015

Columbia Acorn® Fund

Financial Highlights (continued)

Total Distributions to Shareholders	Increase from regulatory settlements	Net Asset Value, End of Period	Total Return	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Increase from regulatory settlements	Net Asset Value, End of Period	Total Return	Total gross expenses^(a)	Total net expenses ^(a)	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

(5.61)	—	$30.30	0.55%	1.08%	1.08%	(0.22)%	17%	$2,694,610
(2.36)	—	$35.78	30.53%	1.07%	1.07%	(0.17)%	18%	$3,869,734
(1.88)	—	$29.36	17.62%	1.06%	1.06% ^(b)	0.27%	16%	$3,233,494
(1.21)	—	$26.63	(4.91)%	1.06%	1.06% ^(b)	(0.33)%	18%	$3,246,833
(0.86)	0.00 ^(c)	$29.24	25.61%	1.07%	1.07% ^(b)	(0.22)%	28%	$3,639,788

(5.61)	—	$26.53	(0.16)%	1.75%	1.75%	(0.91)%	17%	$7,201
(2.32)	—	$32.25	29.63%	1.73%	1.73%	(0.84)%	18%	$19,278
(1.82)	—	$26.80	16.98%	1.65%	1.64% ^(b)	(0.42)%	16%	$33,623
(1.19)	—	$24.53	(5.34)%	1.67%	1.67% ^(b)	(0.98)%	18%	$67,153
(0.84)	0.00 ^(c)	$27.14	24.81%	1.69%	1.69% ^(b)	(0.88)%	28%	$287,650

(5.61)	—	$25.92	(0.16)%	1.77%	1.77%	(0.92)%	17%	$776,370
(2.32)	—	$31.64	29.58%	1.78%	1.78%	(0.88)%	18%	$938,644
(1.82)	—	$26.34	16.77%	1.80%	1.80% ^(b)	(0.46)%	16%	$756,709
(1.19)	—	$24.18	(5.63)%	1.82%	1.82% ^(b)	(1.10)%	18%	$721,446
(0.84)	0.00 ^(c)	$26.85	24.63%	1.85%	1.85% ^(b)	(1.00)%	28%	$829,181

(5.61)	—	$32.03	0.91%	0.70%	0.70%	0.14%	17%	$28,164
(2.36)	—	$37.37	30.99%	0.70%	0.70%	0.16%	18%	$20,383
(1.98)	—	$30.47	18.02%	0.72%	0.72% ^(b)	0.86%	16%	$58,652
(1.28)	—	$27.57	(4.57)%	0.72%	0.72% ^(b)	0.02%	18%	$16,397
(0.86)	—	$30.19	15.94%	0.71% ^(e)	0.71% ^(b)(e)	(0.13)% ^(e)	28%	$11,627

(5.61)	—	$32.51	0.81%	0.84%	0.84%	0.05%	17%	$250,457
(2.37)	—	$37.88	30.85%	0.80%	0.80%	0.16%	18%	$74,188
(1.58)	—	$30.90	6.31%	0.87% ^(e)	0.86% ^(b)(e)	1.24% ^(e)	16%	$17

(5.61)	—	$32.55	0.89%	0.76%	0.76%	0.10%	17%	$458,223
(2.36)	—	$37.89	30.94%	0.75%	0.75%	0.20%	18%	$496,906
(1.60)	—	$30.88	6.33%	0.82% ^(e)	0.81% ^(b)(e)	1.29% ^(e)	16%	$3

(5.61)	—	$32.61	0.94%	0.70%	0.70%	0.13%	17%	$378,780
(2.37)	—	$37.93	30.99%	0.70%	0.70%	0.26%	18%	$1,227,891
(1.61)	—	$30.90	6.34%	0.75% ^(e)	0.75% ^(b)(e)	2.21% ^(e)	16%	$67,012

(5.61)	—	$31.95	0.82%	0.79%	0.79%	0.07%	17%	$11,340,770
(2.36)	—	$37.32	30.90%	0.78%	0.78%	0.12%	18%	$14,703,948
(1.97)	—	$30.45	17.93%	0.78%	0.78% ^(b)	0.57%	16%	$13,374,355
(1.28)	—	$27.56	(4.61)%	0.76%	0.76% ^(b)	(0.03)%	18%	$12,284,748
(0.88)	0.00 ^(c)	$30.19	26.00%	0.76%	0.76% ^(b)	0.09%	28%	$13,330,466

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO110_12_E01_(05/15)

Columbia Acorn International®

Summary of the Fund

Investment Objective

Columbia Acorn International^® (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 21 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class B	Class C	Classes I, R, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	5.00% ^(b)	1.00% ^(c)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class B	Class C	Class I	Class R	Class R4	Class R5	Class Y	Class Z
Management fees	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%	0.75%
Distribution and/or service (12b-1) fees	0.25%	0.75%	1.00%	0.00%	0.50%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.26%	0.50%	0.23%	0.10%	0.37%	0.28%	0.15%	0.10%	0.18%
Total annual Fund operating expenses	1.26%	2.00%	1.98%	0.85%	1.62%	1.03%	0.90%	0.85%	0.93%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

(b)	This charge decreases over time.

(c)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

Example

■	you invest $10,000 in the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn International®

Summary of the Fund (continued)

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$696	$952	$1,227	$2,010
Class B (assuming redemption of all shares at the end of the period)	$703	$927	$1,278	$2,136
Class B (assuming no redemption of shares)	$203	$627	$1,078	$2,136
Class C (assuming redemption of all shares at the end of the period)	$301	$621	$1,068	$2,306
Class C (assuming no redemption of shares)	$201	$621	$1,068	$2,306
Class I (whether or not shares are redeemed)	$ 87	$271	$ 471	$1,049
Class R (whether or not shares are redeemed)	$165	$511	$ 881	$1,922
Class R4 (whether or not shares are redeemed)	$105	$328	$ 569	$1,259
Class R5 (whether or not shares are redeemed)	$ 92	$287	$ 498	$1,108
Class Y (whether or not shares are redeemed)	$ 87	$271	$ 471	$1,049
Class Z (whether or not shares are redeemed)	$ 95	$296	$ 515	$1,143

Portfolio Turnover

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 75% of its net 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 in which the company has a competitive advantage.

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

4	Prospectus 2015

Columbia Acorn International®

Summary of the Fund (continued)

Principal Risks

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

Prospectus 2015

Columbia Acorn International®

Summary of the Fund (continued)

more volatile than securities in more developed markets. Many emerging market countries are heavily dependent on international trade and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries, and some have a higher risk of currency devaluations.

6	Prospectus 2015

Columbia Acorn International®

Summary of the Fund (continued)

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. The bar chart shows how the Fund’s Class Z share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown 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.

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{2nd Quarter 2009}	_33.30%
	_Worst	_{3rd Quarter 2008}	_-23.68%

*	Year to Date return as of March 31, 2015: 4.34%

Prospectus 2015

Columbia Acorn International®

Summary of the Fund (continued)

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class Z	09/23/1992
returns before taxes		-4.28%	8.47%	8.95%
returns after taxes on distributions		-5.65%	7.55%	8.06%
returns after taxes on distributions and sale of Fund shares		-0.99%	6.76%	7.49%
Class A returns before taxes	10/16/2000	-10.05%	6.84%	7.95%
Class B returns before taxes	10/16/2000	-9.75%	7.06%	7.87%
Class C returns before taxes	10/16/2000	-6.16%	7.31%	7.76%
Class I returns before taxes	09/27/2010	-4.20%	8.54%	8.99%
Class R returns before taxes	08/02/2011	-4.95%	7.76%	8.26%
Class R4 returns before taxes	11/08/2012	-4.39%	8.43%	8.94%
Class R5 returns before taxes	08/02/2011	-4.25%	8.48%	8.95%
Class Y returns before taxes	11/08/2012	-4.21%	8.50%	8.97%
S&P Global ex-U.S. Between $500 Million and $5 Billion^® Index (reflects no deductions for fees, expenses or taxes)		-1.76%	7.14%	7.65%
S&P Global Ex-U.S. SmallCap^® Index (reflects no deductions for fees, expenses or taxes)		-3.11%	7.41%	7.27%
MSCI EAFE Index (Net) (reflects reinvested dividends net of withholding taxes but reflects no deductions for fees, expenses or other taxes)		-4.90%	5.33%	4.43%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
P. Zachary Egan, CFA	International Chief Investment Officer, Portfolio Manager and Analyst of the Investment Manager	Co-manager since 2003	1999
Louis J. Mendes, CFA	Portfolio Manager and Analyst	Co-manager since 2003	2001

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

8	Prospectus 2015

Columbia Acorn International®

Summary of the Fund (continued)

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A, B* & C	All accounts other than IRAs	$2,000	$100
Classes A, B* & C	IRAs	$1,000	$100
Classes I, R, R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

*	Class B shares are generally closed to new and existing shareholders.

There is no minimum additional investment for any share class.

Tax Information

Payments to Broker-Dealers and Other Financial Intermediaries

Prospectus 2015

Columbia Acorn International®

More Information About the Fund

Investment Objective

Columbia Acorn International^® (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

10	Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar. Foreign securities may also be less liquid than securities of U.S. companies so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

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.

Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries.

12	Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

liquidate other investments, or forego another, more appealing investment opportunity as a result of illiquidity in the markets. The Investment Manager will fair value in good faith any securities it deems to be illiquid under consistently applied procedures established by the Fund’s Board. Market conditions are always changing and vary by country and industry sector, and investing in international markets involves unique risks. In the wake of the 2007-2009 financial crisis, trading volumes in both emerging and developed international markets declined significantly and have stayed at generally reduced levels since then. Although it is difficult to accurately assess trends in trading volumes in foreign markets, because some amount of activity has migrated to alternative trading venues, a reduction in trading volumes poses challenges to the Fund. This is particularly so because the Fund focuses on small- and mid-cap companies that usually have lower trading volumes and often takes sizeable positions in portfolio companies. As a result of lower trading volumes, it may take longer to buy or sell securities, which can exacerbate the Fund’s exposure to volatile markets. The Fund may also be limited in its ability to execute favorable trades in portfolio securities in response to changes in share prices and fundamentals. If the Fund is forced to sell securities to meet redemption requests or other cash needs, or in the case of an event affecting liquidity in a particular market or markets, it may be forced to dispose of those securities under disadvantageous circumstances and at a loss. As the Fund grows in size, these considerations take on increasing significance and may adversely impact performance.

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

Investment Guidelines

Holding Other Kinds of Investments

Investing in Affiliated Funds

Investing in Money Market Funds

14	Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

Lending of Portfolio Securities

Investing Defensively

Portfolio Holdings Disclosure

Cybersecurity

Use of Benchmarks

Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Additional Information on Portfolio Turnover

Cash Flows

Understanding Annual Fund Operating Expenses

16	Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

FUNDamentals

Other Expenses

Fee Waiver/Expense Reimbursement Arrangements

The Transfer Agent has voluntarily agreed to waive a portion of total annual Fund operating expenses attributable to transfer agency fees incurred by Class A, Class B and Class C shares of the Fund. Pursuant to this voluntary arrangement, total annual Fund operating expenses will be reduced by 0.04%, 0.03% and 0.02% for Class A, Class B and Class C shares, respectively. This arrangement may be modified or discontinued at any time.

Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates and any predecessor firms that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

Board of Trustees

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

Primary Service Providers

The Investment Manager

Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

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.

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 0.75% of average daily net assets of the Fund. A discussion regarding the basis for the Board approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Portfolio Managers

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
P. Zachary Egan, CFA	International Chief Investment Officer, Portfolio Manager and Analyst of the Investment Manager	Co-manager since 2003	1999
Louis J. Mendes, CFA	Portfolio Manager and Analyst	Co-manager since 2003	2001

The Administrator

Annual Administration Fee, as a % of Aggregate 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%

18	Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

The Distributor

The Transfer Agent

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

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

Prospectus 2015

Columbia Acorn International®

More Information About the Fund (continued)

■

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

■

Certain Legal Matters

20	Prospectus 2015

Columbia Acorn International®

Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

Prospectus 2015

Columbia Acorn International®

Choosing a Share Class (continued)

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.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

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Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

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Columbia Acorn International®

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

24	Prospectus 2015

Columbia Acorn International®

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge

FUNDamentals

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 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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Columbia Acorn International®

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

26	Prospectus 2015

Columbia Acorn International®

Choosing a Share Class (continued)

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

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Columbia Acorn International®

Choosing a Share Class (continued)

Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

28	Prospectus 2015

Columbia Acorn International®

Choosing a Share Class (continued)

FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

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Columbia Acorn International®

Choosing a Share Class (continued)

Front-End Sales Charge Waivers

CDSC Waivers

Repurchases

Restrictions and Changes in Terms and Conditions

30	Prospectus 2015

Columbia Acorn International®

Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

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Columbia Acorn International®

Choosing a Share Class (continued)

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Columbia Acorn International®

Buying, Selling and Exchanging Shares

Share Price Determination

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

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

Business Days

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

34	Prospectus 2015

Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

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.

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Opening an Account and Placing Orders

Accounts Established Directly with the Fund

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Written Transactions

Telephone Transactions

Online Transactions

Wire Transactions

38	Prospectus 2015

Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Electronic Funds Transfer

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Class R Shares

Class R4 Shares

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

40	Prospectus 2015

Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

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 so long as the initial Class Z account was funded by July 2, 2013.

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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

Class Z Shares Minimum Initial Investments

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

■

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

■

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

■	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.

■

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

■

■	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.

■

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

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

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

minimum initial investment amount. 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.

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

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Buying, Selling and Exchanging Shares (continued)

Systematic Exchanges

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

■

■	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.

■

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Columbia Acorn International®

Buying, Selling and Exchanging Shares (continued)

■	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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Columbia Acorn International®

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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

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Columbia Acorn International®

Distributions and Taxes (continued)

Taxes

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

■

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Distributions and Taxes (continued)

■

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 your income for U.S. federal income tax purposes your share of the qualifying foreign income taxes paid by the Fund in respect of its foreign portfolio securities. You may be able to claim a foreign tax credit or deduction in respect of this amount, subject to certain limitations. There is no assurance that the Fund will make this election for a taxable year, even if it is eligible to do so.

■

FUNDamentals

Taxes

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Financial Highlights

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Columbia Acorn International®

Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations			Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Reimbursement from affiliate	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$46.63	0.42	(2.51)	—	(2.09)	(0.55)	(2.31)
Year Ended December 31, 2013	$40.79	0.45	8.37	—	8.82	(1.05)	(1.93)
Year Ended December 31, 2012	$34.15	0.47	6.75	—	7.22	(0.58)	—
Year Ended December 31, 2011	$40.87	0.32	(6.02)	0.00 ^(c)	(5.70)	(1.02)	—
Year Ended December 31, 2010	$34.13	0.22	7.21	—	7.43	(0.69)	—
Class B
Year Ended December 31, 2014	$45.24	0.07	(2.42)	—	(2.35)	(0.20)	(2.31)
Year Ended December 31, 2013	$39.67	0.12	8.10	—	8.22	(0.72)	(1.93)
Year Ended December 31, 2012	$33.17	0.19	6.55	—	6.74	(0.24)	—
Year Ended December 31, 2011	$39.96	0.06	(5.85)	0.00 ^(c)	(5.79)	(1.00)	—
Year Ended December 31, 2010	$33.22	0.03	7.02	—	7.05	(0.31)	—
Class C
Year Ended December 31, 2014	$45.04	0.07	(2.40)	—	(2.33)	(0.20)	(2.31)
Year Ended December 31, 2013	$39.50	0.10	8.08	—	8.18	(0.71)	(1.93)
Year Ended December 31, 2012	$33.03	0.18	6.52	—	6.70	(0.23)	—
Year Ended December 31, 2011	$39.79	0.04	(5.86)	0.00 ^(c)	(5.82)	(0.94)	—
Year Ended December 31, 2010	$33.08	(0.05)	7.03	—	6.98	(0.27)	—
Class I
Year Ended December 31, 2014	$46.71	0.59	(2.51)	—	(1.92)	(0.72)	(2.31)
Year Ended December 31, 2013	$40.86	0.66	8.34	—	9.00	(1.22)	(1.93)
Year Ended December 31, 2012	$34.33	0.57	6.83	—	7.40	(0.87)	—
Year Ended December 31, 2011	$40.92	0.37	(5.94)	0.00 ^(c)	(5.57)	(1.02)	—
Year Ended December 31, 2010^(f)	$37.69	0.08	3.49	—	3.57	(0.34)	—
Class R
Year Ended December 31, 2014	$46.60	0.24	(2.50)	—	(2.26)	(0.36)	(2.31)
Year Ended December 31, 2013	$40.79	0.26	8.36	—	8.62	(0.88)	(1.93)
Year Ended December 31, 2012	$34.11	0.21	6.89	—	7.10	(0.42)	—
Year Ended December 31, 2011^(h)	$40.11	(0.00) ^(c)	(6.00)	0.00 ^(c)	(6.00)	—	—
Class R4
Year Ended December 31, 2014	$46.99	0.50	(2.52)	—	(2.02)	(0.64)	(2.31)
Year Ended December 31, 2013	$41.08	0.34	8.67	—	9.01	(1.17)	(1.93)
Year Ended December 31, 2012⁽ⁱ⁾	$39.86	(0.00) ^(c)	1.81	—	1.81	(0.59)	—
Class R5
Year Ended December 31, 2014	$46.66	0.57	(2.51)	—	(1.94)	(0.70)	(2.31)
Year Ended December 31, 2013	$40.81	0.63	8.34	—	8.97	(1.19)	(1.93)
Year Ended December 31, 2012	$34.31	0.75	6.62	—	7.37	(0.87)	—
Year Ended December 31, 2011^(j)	$40.24	0.09	(6.02)	0.00 ^(c)	(5.93)	—	—
Class Y
Year Ended December 31, 2014	$46.99	0.58	(2.52)	—	(1.94)	(0.72)	(2.31)
Year Ended December 31, 2013	$41.08	0.57	8.48	—	9.05	(1.21)	(1.93)
Year Ended December 31, 2012^(k)	$39.90	0.04	1.78	—	1.82	(0.64)	—
Class Z
Year Ended December 31, 2014	$46.68	0.56	(2.51)	—	(1.95)	(0.69)	(2.31)
Year Ended December 31, 2013	$40.84	0.58	8.38	—	8.96	(1.19)	(1.93)
Year Ended December 31, 2012	$34.31	0.59	6.78	—	7.37	(0.84)	—
Year Ended December 31, 2011	$40.92	0.48	(6.07)	0.00 ^(c)	(5.59)	(1.02)	—
Year Ended December 31, 2010	$34.26	0.35	7.23	—	7.58	(0.92)	—

Notes to Financial Highlights

(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(b)	Had the Investment Manager and/or its affiliates not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(c)

Rounds to zero.

(d)

The benefits derived from custody fees paid indirectly had an impact of 0.01%.

(e)	During the year ended December 31, 2011, Columbia Management reimbursed the Fund for a loss on a trading error. Had the Fund not received this reimbursement, total return would have been lower by less than 0.01%.

(f)

Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(g)

Annualized.

(h)

Class R shares commenced operations on August 2, 2011. Per share data and total return reflect activity from that date.

(i)

Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(j)

Class R5 shares commenced operations on August 2, 2011. Per share data and total return reflect activity from that date.

(k)	Class Y shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

52	Prospectus 2015

Columbia Acorn International®

Financial Highlights (continued)

Total Distributions to Shareholders	Redemption fees added to paid in capital	Increase from regulatory settlements	Net Asset Value, End of Period	Total Return	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Redemption fees added to paid in capital	Increase from regulatory settlements	Net Asset Value, End of Period	Total Return	Total gross expenses ^(a)	Total net expenses ^(a)	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

(2.86)	—	—	$41.68	(4.58)% ^(b)	1.26%	1.22%	0.91%	28%	$946,553
(2.98)	—	—	$46.63	22.00% ^(b)	1.27%	1.23%	1.02%	45%	$1,089,263
(0.58)	—	0.00 ^(c)	$40.79	21.21% ^(b)	1.28%	1.24% ^(d)	1.22%	33%	$1,007,236
(1.02)	—	0.00 ^(c)	$34.15	(14.37)% ^(b)(e)	1.32%	1.30% ^(d)	0.84%	32%	$918,112
(0.69)	0.00 ^(c)	0.00 ^(c)	$40.87	22.23%	1.35%	1.35% ^(d)	0.62%	25%	$810,603

(2.51)	—	—	$40.38	(5.29)% ^(b)	2.00%	1.97%	0.16%	28%	$6,516
(2.65)	—	—	$45.24	21.08% ^(b)	2.00%	1.97%	0.27%	45%	$13,218
(0.24)	—	0.00 ^(c)	$39.67	20.33% ^(b)	2.00%	1.97% ^(d)	0.51%	33%	$17,910
(1.00)	—	0.00 ^(c)	$33.17	(14.92)% ^(b)(e)	1.98%	1.96% ^(d)	0.15%	32%	$24,510
(0.31)	0.00 ^(c)	0.00 ^(c)	$39.96	21.49%	1.96%	1.96% ^(d)	0.08%	25%	$29,368

(2.51)	—	—	$40.20	(5.27)% ^(b)	1.99%	1.97%	0.16%	28%	$103,691
(2.64)	—	—	$45.04	21.07% ^(b)	2.01%	1.99%	0.23%	45%	$110,875
(0.23)	—	0.00 ^(c)	$39.50	20.31% ^(b)	2.02%	2.00% ^(d)	0.48%	33%	$92,748
(0.94)	—	0.00 ^(c)	$33.03	(15.02)% ^(b)(e)	2.07%	2.06% ^(d)	0.10%	32%	$97,328
(0.27)	0.00 ^(c)	0.00 ^(c)	$39.79	21.34%	2.11%	2.11% ^(d)	(0.13)%	25%	$110,931

(3.03)	—	—	$41.76	(4.20)%	0.85%	0.85%	1.26%	28%	$38,804
(3.15)	—	—	$46.71	22.43%	0.85%	0.85%	1.49%	45%	$29,418
(0.87)	—	0.00 ^(c)	$40.86	21.69%	0.88%	0.88% ^(d)	1.48%	33%	$97,484
(1.02)	—	0.00 ^(c)	$34.33	(14.02)% ^(e)	0.91%	0.91% ^(d)	0.99%	32%	$50,335
(0.34)	0.00 ^(c)	—	$40.92	9.50%	0.94% ^(g)	0.94% ^(d)(g)	0.77% ^(g)	25%	$66,581

(2.67)	—	—	$41.67	(4.95)%	1.63%	1.63%	0.52%	28%	$5,560
(2.81)	—	—	$46.60	21.50%	1.63%	1.63%	0.58%	45%	$5,822
(0.42)	—	0.00 ^(c)	$40.79	20.83%	1.52%	1.51% ^(d)	0.54%	33%	$2,799
—	—	0.00 ^(c)	$34.11	(14.96)%	1.59% ^(g)	1.59% ^(d)(g)	(0.02)% ^(g)	32%	$2,130

(2.95)	—	—	$42.02	(4.39)%	1.04%	1.04%	1.07%	28%	$424,425
(3.10)	—	—	$46.99	22.32%	1.03%	1.03%	0.73%	45%	$355,616
(0.59)	—	—	$41.08	4.57%	1.03% ^(g)	1.02% ^(d)(g)	(0.02)% ^(g)	33%	$15

(3.01)	—	—	$41.71	(4.25)%	0.90%	0.90%	1.23%	28%	$397,882
(3.12)	—	—	$46.66	22.38%	0.91%	0.91%	1.40%	45%	$274,415
(0.87)	—	0.00 ^(c)	$40.81	21.61%	0.89%	0.89% ^(d)	1.99%	33%	$242
—	—	0.00 ^(c)	$34.31	(14.74)%	0.91% ^(g)	0.91% ^(d)(g)	0.65% ^(g)	32%	$2,038

(3.03)	—	—	$42.02	(4.21)%	0.85%	0.85%	1.25%	28%	$225,012
(3.14)	—	—	$46.99	22.44%	0.86%	0.86%	1.26%	45%	$155,140
(0.64)	—	—	$41.08	4.59%	0.91% ^(g)	0.90% ^(d)(g)	0.75% ^(g)	33%	$30,856

(3.00)	—	—	$41.73	(4.28)%	0.93%	0.93%	1.20%	28%	$5,585,035
(3.12)	—	—	$46.68	22.33%	0.93%	0.93%	1.30%	45%	$6,293,552
(0.84)	—	0.00 ^(c)	$40.84	21.60%	0.93%	0.93% ^(d)	1.53%	33%	$5,494,506
(1.02)	—	0.00 ^(c)	$34.31	(14.06)% ^(e)	0.95%	0.95% ^(d)	1.24%	32%	$4,322,500
(0.92)	0.00 ^(c)	0.00 ^(c)	$40.92	22.70%	0.97%	0.97% ^(d)	0.99%	25%	$5,107,580

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO111_12_E01_(05/15)

Columbia Acorn International Select^SM

Summary of the Fund

Investment Objective

Columbia Acorn International Select^SM (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 22 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class B	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	5.00% ^(b)	1.00% ^(c)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class B	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees	0.94%	0.94%	0.94%	0.94%	0.94%	0.94%	0.94%	0.94%
Distribution and/or service (12b-1) fees	0.25%	0.75%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.27%	0.42%	0.29%	0.15%	0.26%	0.20%	0.15%	0.23%
Acquired fund fees and expenses	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%	0.01%
Total annual Fund operating expenses^(d)	1.47%	2.12%	2.24%	1.10%	1.21%	1.15%	1.10%	1.18%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

(b)	This charge decreases over time.

(c)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

(d)

“Total annual Fund operating expenses” include acquired fund fees and expenses (expenses the Fund incurs indirectly through its investments in other investment companies) and may be higher than “Total Net Expenses” shown in the Financial Highlights section of this prospectus because “Total Net Expenses” do not include acquired fund fees and expenses.

Example

■	you invest $10,000 in the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn International Select^SM

Summary of the Fund (continued)

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$716	$1,013	$1,332	$2,231
Class B (assuming redemption of all shares at the end of the period)	$715	$ 964	$1,339	$2,286
Class B (assuming no redemption of shares)	$215	$ 664	$1,139	$2,286
Class C (assuming redemption of all shares at the end of the period)	$327	$ 700	$1,200	$2,575
Class C (assuming no redemption of shares)	$227	$ 700	$1,200	$2,575
Class I (whether or not shares are redeemed)	$112	$ 350	$ 606	$1,340
Class R4 (whether or not shares are redeemed)	$123	$ 384	$ 665	$1,466
Class R5 (whether or not shares are redeemed)	$117	$ 365	$ 633	$1,398
Class Y (whether or not shares are redeemed)	$112	$ 350	$ 606	$1,340
Class Z (whether or not shares are redeemed)	$120	$ 375	$ 649	$1,432

Portfolio Turnover

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 initial 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. Under normal circumstances, the Fund may invest in companies with market capitalizations above $25 billion at the time of initial investment, provided that immediately after that investment a majority of its net assets would be invested in companies whose market capitalizations were under $25 billion at the time of initial investment.

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 invests in a limited number of foreign companies (generally between 40-60), offering the potential to provide above-average growth over time. In pursuit of the Fund’s objective, the portfolio managers will take advantage of the research and stock-picking capabilities of the Investment Manager and will generally concentrate the Fund’s investments in those sectors, companies, geographic regions or industries that the portfolio managers believe offer the best investment return potential.

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

4	Prospectus 2015

Columbia Acorn International Select^SM

Summary of the Fund (continued)

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

Principal Risks

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Select Portfolio Risk. Because the Fund may invest in a limited number of companies, the Fund as a whole is subject to greater risk of loss if any of its portfolio securities decline in price. In addition, the Fund’s holdings and weightings will diverge significantly from its primary benchmark’s holdings and weightings and the Fund may therefore experience greater risk and volatility relative to the benchmark. Because the Fund may invest in more than one company concentrated in a similar industry, sector or geographic region, the Fund may be even more concentrated than the number of companies it may hold would suggest.

Real Estate-Related Investment Risk. Investments in real estate investment trusts (REITs) and in securities of other companies (wherever organized) principally engaged in the real estate industry subject the Fund to, among other things, risks similar to those of direct investments in real estate and the real estate industry in general. These include risks related to general and local economic conditions, possible lack of availability of financing and changes in interest rates or property values. REITs are entities that either own properties or make construction or mortgage loans, and also may include operating or finance companies. The value of interests in a REIT may be affected by, among other factors, changes in the value of the underlying properties owned by the REIT, changes in the prospect for earnings and/or cash flow growth of the REIT itself, defaults by borrowers or tenants, market saturation, decreases in market rates for rents, and other economic, political, or regulatory matters affecting the real estate industry, including REITs. REITs and similar non-U.S. entities depend upon specialized management skills, may have limited financial resources, may have less trading volume in their securities, and may be subject to more abrupt or erratic price movements than the overall securities markets. REITs are also subject to the risk of failing to qualify for

Prospectus 2015

Columbia Acorn International Select^SM

Summary of the Fund (continued)

favorable tax treatment under the Internal Revenue Code of 1986, as amended. Some REITs (especially mortgage REITs) are affected by risks similar to those associated with investments in debt securities including changes in interest rates and the quality of credit extended.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

6	Prospectus 2015

Columbia Acorn International Select^SM

Summary of the Fund (continued)

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

Performance Information

Prospectus 2015

Columbia Acorn International Select^SM

Summary of the Fund (continued)

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{2nd Quarter 2009}	_23.44%
	_Worst	_{3rd Quarter 2008}	_-24.76%

*	Year to Date return as of March 31, 2015: 1.48%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class Z	11/23/1998
returns before taxes		-6.79%	7.57%	7.76%
returns after taxes on distributions		-9.33%	5.78%	6.71%
returns after taxes on distributions and sale of Fund shares		-1.47%	6.16%	6.52%
Class A returns before taxes	10/16/2000	-12.39%	5.95%	6.78%
Class B returns before taxes	10/16/2000	-11.77%	6.23%	6.73%
Class C returns before taxes	10/16/2000	-8.61%	6.37%	6.57%
Class I returns before taxes	09/27/2010	-6.72%	7.63%	7.79%
Class R4 returns before taxes	11/08/2012	-6.83%	7.55%	7.75%
Class R5 returns before taxes	11/08/2012	-6.77%	7.58%	7.77%
Class Y returns before taxes	11/08/2012	-6.71%	7.60%	7.78%
S&P Developed Ex-U.S. Between $2 Billion and $10 Billion^® Index (reflects no deductions for fees, expenses or taxes)		-2.10%	7.53%	6.25%
MSCI EAFE Index (Net) (reflects reinvested dividends net of withholding taxes but reflects no deductions for fees, expenses or other taxes)		-4.90%	5.33%	4.43%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Christopher J. Olson, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since 2001	2001
Andreas Waldburg-Wolfegg	Portfolio Manager and Analyst	Co-manager since 2015	2002

8	Prospectus 2015

Columbia Acorn International Select^SM

Summary of the Fund (continued)

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A, B* & C	All accounts other than IRAs	$2,000	$100
Classes A, B* & C	IRAs	$1,000	$100
Classes I, R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

*	Class B shares are generally closed to new and existing shareholders.

There is no minimum additional investment for any share class.

Tax Information

Payments to Broker-Dealers and Other Financial Intermediaries

Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund

Investment Objective

Columbia Acorn International Select^SM (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

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 Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

10	Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund (continued)

Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund (continued)

Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries.

12	Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund (continued)

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.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund (continued)

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Investment Guidelines

Holding Other Kinds of Investments

Investing in Affiliated Funds

14	Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund (continued)

structures transactions over a reasonable period of time in order to manage the potential impact of the buy and sell decisions for the affiliated products, those affiliated products, including funds-of-funds, may pay more or less (for purchase activity), or receive more or less (for redemption activity), for shares of the Underlying Funds than if the transactions were executed in one transaction. In addition, substantial redemptions by affiliated products within a short period of time could require the Underlying Fund to liquidate positions more rapidly than would otherwise be desirable, which may have the effect of reducing or eliminating potential gain or causing it to realize a loss. Substantial redemptions may also adversely affect the ability of the Underlying Fund to implement its investment strategy. The Investment Manager or Columbia Management also has an economic conflict of interest in determining the allocation of affiliated products’ assets among the Underlying Funds, as it earns different fees from the various Underlying Funds.

Investing in Money Market Funds

Lending of Portfolio Securities

Investing Defensively

Portfolio Holdings Disclosure

Cybersecurity

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Columbia Acorn International Select^SM

More Information About the Fund (continued)

of Fund shareholders to transact business, violations of applicable privacy and other laws, regulatory fines, penalties, reputational damage, reimbursement or other compensation costs, and/or additional compliance costs. The Fund and its shareholders could be negatively impacted as a result. See the discussion of Cyber Risk in the SAI for further information.

Use of Benchmarks

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Additional Information on Portfolio Turnover

Cash Flows

Understanding Annual Fund Operating Expenses

16	Prospectus 2015

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More Information About the Fund (continued)

ratios to reflect any differences in the Fund’s average net assets between the most recently completed fiscal year and the date of this prospectus or a later date. In general, the Fund’s expense ratios will increase as its net assets decrease, such that the Fund’s actual expense ratios may be higher than the expense ratios presented in the Annual Fund Operating Expenses table if assets fall. Any commitment by the Investment Manager and/or its affiliates to waive fees and/or cap (reimburse) expenses is expected, in part, to limit the impact of any increase in the Fund’s expense ratios that would otherwise result because of a decrease in the Fund’s assets in the current fiscal year. The Fund’s annual operating expenses are comprised of (i) investment management fees, (ii) distribution and/or service fees, and (iii) other expenses. Management fees do not vary by class, but distribution and/or service fees and other expenses may vary by class.

FUNDamentals

Other Expenses

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

The Investment Manager has voluntarily agreed to reimburse expenses so that the Fund’s ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund’s investments in other investment companies, if any), after giving effect to any balance credits or overdraft charges from the Fund’s custodian, do not exceed the annual rates of:

Columbia Acorn International Select
Class A	1.70%
Class B	2.20%
Class C	2.45%
Class I	1.37%
Class R4	1.45%
Class R5	1.42%
Class Y	1.37%
Class Z	1.45%

The Investment Manager or the Fund may modify or discontinue this arrangement on 30 days’ notice.

Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates and any predecessor firms that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

Board of Trustees

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Columbia Acorn International Select^SM

More Information About the Fund (continued)

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.

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

Primary Service Providers

The Investment Manager

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 approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Portfolio Managers

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Christopher J. Olson, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since 2001	2001
Andreas Waldburg-Wolfegg	Portfolio Manager and Analyst	Co-manager since 2015	2002

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More Information About the Fund (continued)

Mr. Olson has been associated with the Investment Manager or its predecessors as an investment professional since 2001 and has been a 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

Annual Administration Fee, as a % of Aggregate 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

The Transfer Agent

Prospectus 2015

Columbia Acorn International Select^SM

More Information About the Fund (continued)

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

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

■

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

■

Certain Legal Matters

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Columbia Acorn International Select^SM

Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

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Choosing a Share Class (continued)

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.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

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Columbia Acorn International Select^SM

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

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Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

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Columbia Acorn International Select^SM

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge

FUNDamentals

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 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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Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

Prospectus 2015

Columbia Acorn International Select^SM

Choosing a Share Class (continued)

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

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Choosing a Share Class (continued)

Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

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Columbia Acorn International Select^SM

Choosing a Share Class (continued)

FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

30	Prospectus 2015

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Choosing a Share Class (continued)

Front-End Sales Charge Waivers

CDSC Waivers

Repurchases

Restrictions and Changes in Terms and Conditions

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Columbia Acorn International Select^SM

Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

32	Prospectus 2015

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Choosing a Share Class (continued)

Prospectus 2015

Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares

Share Price Determination

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

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

Business Days

34	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

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Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

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Buying, Selling and Exchanging Shares (continued)

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.

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Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares (continued)

Opening an Account and Placing Orders

Accounts Established Directly with the Fund

38	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

Written Transactions

Telephone Transactions

Online Transactions

Wire Transactions

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Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares (continued)

Electronic Funds Transfer

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

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Buying, Selling and Exchanging Shares (continued)

Class R Shares

Class R4 Shares

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

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Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares (continued)

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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

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Buying, Selling and Exchanging Shares (continued)

Class Z Shares Minimum Initial Investments

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

■

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

■

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

■	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.

■

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

■

■	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.

■

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Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares (continued)

■	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

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

44	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

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Columbia Acorn International Select^SM

Buying, Selling and Exchanging Shares (continued)

Systematic Exchanges

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

■

■	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.

■

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Buying, Selling and Exchanging Shares (continued)

■	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

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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Columbia Acorn International Select^SM

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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

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Distributions and Taxes (continued)

Taxes

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

■

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Distributions and Taxes (continued)

■

FUNDamentals

Taxes

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Financial Highlights

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Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations		Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$26.91	0.29	(2.17)	(1.88)	(0.10)	(2.89)
Year Ended December 31, 2013	$25.61	0.29	3.29	3.58	(0.37)	(1.91)
Year Ended December 31, 2012	$24.26	0.39	4.92	5.31	(1.75)	(2.21)
Year Ended December 31, 2011	$28.01	0.18	(2.95)	(2.77)	(0.59)	(0.39)
Year Ended December 31, 2010	$23.39	0.08	4.84	4.92	(0.30)	—
Class B
Year Ended December 31, 2014	$25.53	0.10	(2.05)	(1.95)	—	(2.89)
Year Ended December 31, 2013	$24.40	0.11	3.12	3.23	(0.19)	(1.91)
Year Ended December 31, 2012	$23.27	0.23	4.69	4.92	(1.58)	(2.21)
Year Ended December 31, 2011	$26.72	0.01	(2.82)	(2.81)	(0.25)	(0.39)
Year Ended December 31, 2010	$22.34	(0.06)	4.62	4.56	(0.18)	—
Class C
Year Ended December 31, 2014	$25.39	0.07	(2.03)	(1.96)	—	(2.89)
Year Ended December 31, 2013	$24.28	0.08	3.10	3.18	(0.16)	(1.91)
Year Ended December 31, 2012	$23.17	0.18	4.67	4.85	(1.53)	(2.21)
Year Ended December 31, 2011	$26.58	(0.04)	(2.81)	(2.85)	(0.17)	(0.39)
Year Ended December 31, 2010	$22.21	(0.10)	4.60	4.50	(0.13)	—
Class I
Year Ended December 31, 2014	$27.19	0.39	(2.20)	(1.81)	(0.20)	(2.89)
Year Ended December 31, 2013	$25.85	0.39	3.32	3.71	(0.46)	(1.91)
Year Ended December 31, 2012	$24.45	0.51	4.94	5.45	(1.84)	(2.21)
Year Ended December 31, 2011	$28.33	0.31	(2.97)	(2.66)	(0.83)	(0.39)
Year Ended December 31, 2010^(g)	$26.11	0.03	2.19	2.22	—	—
Class R4
Year Ended December 31, 2014	$27.36	0.37	(2.22)	(1.85)	(0.17)	(2.89)
Year Ended December 31, 2013	$25.99	0.29	3.42	3.71	(0.43)	(1.91)
Year Ended December 31, 2012⁽ⁱ⁾	$29.98	(0.02)	(0.09) ^(j)	(0.11)	(1.79)	(2.09)
Class R5
Year Ended December 31, 2014	$27.34	0.36	(2.19)	(1.83)	(0.19)	(2.89)
Year Ended December 31, 2013	$25.98	0.38	3.35	3.73	(0.46)	(1.91)
Year Ended December 31, 2012^(k)	$29.98	(0.02)	(0.09) ^(j)	(0.11)	(1.80)	(2.09)
Class Y
Year Ended December 31, 2014	$27.33	0.40	(2.21)	(1.81)	(0.21)	(2.89)
Year Ended December 31, 2013	$25.98	0.11	3.62	3.73	(0.47)	(1.91)
Year Ended December 31, 2012^(l)	$29.99	(0.02)	(0.09) ^(j)	(0.11)	(1.81)	(2.09)
Class Z
Year Ended December 31, 2014	$27.20	0.38	(2.21)	(1.83)	(0.18)	(2.89)
Year Ended December 31, 2013	$25.86	0.37	3.33	3.70	(0.45)	(1.91)
Year Ended December 31, 2012	$24.46	0.49	4.95	5.44	(1.83)	(2.21)
Year Ended December 31, 2011	$28.33	0.29	(2.98)	(2.69)	(0.79)	(0.39)
Year Ended December 31, 2010	$23.64	0.18	4.89	5.07	(0.38)	—

Notes to Financial Highlights

(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(b)	Ratios include line of credit interest expense which is less than 0.01%.

(c)	The benefits derived from custody fees paid indirectly had an impact of 0.01%.

(d)	The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(e)	Rounds to zero.

(f)	Had the Investment Manager and/or its affiliates not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(g)	Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(h)	Annualized.

(i)	Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(j)

Calculation of the net gain (loss) per share (both realized and unrealized) does not correlate to the aggregate realized and unrealized gain (loss) presented in the Statements of Operations due to the timing of subscriptions and redemptions of Fund shares in relation to fluctuations in the market value of the portfolio.

(k)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(l)	Class Y shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

52	Prospectus 2015

Columbia Acorn International Select^SM

Financial Highlights (continued)

Total Distributions to Shareholders	Redemption fees added to paid in capital	Increase from regulatory settlements	Net Asset Value, End of Period	Total Return	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Redemption fees added to paid in capital	Increase from regulatory settlements	Net Asset Value, End of Period	Total Return	Total gross expenses ^(a)	Total net expenses ^(a)	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

(2.99)	—	—	$22.04	(7.06)%	1.47%	1.47%	1.05%	58%	$53,419
(2.28)	—	—	$26.91	14.42%	1.47%	1.47%	1.08%	72%	$73,911
(3.96)	—	—	$25.61	22.05%	1.49% ^(b)	1.49% ^(b)(c)	1.43%	63%	$74,167
(0.98)	—	—	$24.26	(10.11)%	1.51%	1.51% ^(d)	0.66%	44%	$56,350
(0.30)	0.00 ^(e)	0.00 ^(e)	$28.01	21.41%	1.56%	1.56% ^(d)	0.33%	42%	$71,668

(2.89)	—	—	$20.69	(7.71)%	2.11%	2.11%	0.39%	58%	$355
(2.10)	—	—	$25.53	13.67%	2.14%	2.14%	0.43%	72%	$873
(3.79)	—	—	$24.40	21.29%	2.11% ^(b)	2.10% ^(b)(c)	0.87%	63%	$1,250
(0.64)	—	—	$23.27	(10.64)%	2.14%	2.14% ^(d)	0.04%	44%	$1,774
(0.18)	0.00 ^(e)	0.00 ^(e)	$26.72	20.63% ^(f)	2.24%	2.20% ^(d)	(0.27)%	42%	$3,030

(2.89)	—	—	$20.54	(7.80)%	2.23%	2.23%	0.29%	58%	$8,057
(2.07)	—	—	$25.39	13.52%	2.26%	2.26%	0.32%	72%	$10,311
(3.74)	—	—	$24.28	21.10%	2.28% ^(b)	2.27% ^(b)(c)	0.67%	63%	$9,786
(0.56)	—	—	$23.17	(10.81)%	2.31%	2.31% ^(d)	(0.14)%	44%	$8,704
(0.13)	0.00 ^(e)	0.00 ^(e)	$26.58	20.45%	2.36%	2.36% ^(d)	(0.45)%	42%	$11,885

(3.09)	—	—	$22.29	(6.72)%	1.11%	1.11%	1.41%	58%	$2
(2.37)	—	—	$27.19	14.82%	1.13%	1.13%	1.43%	72%	$3
(4.05)	—	—	$25.85	22.48%	1.15%	1.14% ^(c)	1.84%	63%	$2
(1.22)	—	—	$24.45	(9.68)%	1.04%	1.04% ^(d)	1.12%	44%	$2
—	—	—	$28.33	8.50%	1.14% ^(h)	1.14% ^(d)(h)	0.44% ^(h)	42%	$3

(3.06)	—	—	$22.45	(6.83)%	1.21%	1.21%	1.33%	58%	$974
(2.34)	—	—	$27.36	14.72%	1.24%	1.24%	1.06%	72%	$417
(3.88)	—	—	$25.99	(0.27)%	1.30% ^(b)(h)	1.30% ^(b)(c)(h)	(0.55)% ^(h)	63%	$13

(3.08)	—	—	$22.43	(6.77)%	1.15%	1.15%	1.30%	58%	$2,593
(2.37)	—	—	$27.34	14.80% ^(f)	1.15%	1.15%	1.40%	72%	$956
(3.89)	—	—	$25.98	(0.27)%	1.29% ^(h)	1.28% ^(c)(h)	(0.55)% ^(h)	63%	$2

(3.10)	—	—	$22.42	(6.71)%	1.09%	1.09%	1.43%	58%	$11,755
(2.38)	—	—	$27.33	14.82%	1.09%	1.09%	0.40%	72%	$13,318
(3.90)	—	—	$25.98	(0.25)%	1.21% ^(h)	1.20% ^(c)(h)	(0.48)% ^(h)	63%	$2

(3.07)	—	—	$22.30	(6.79)%	1.17%	1.17%	1.36%	58%	$175,764
(2.36)	—	—	$27.20	14.75%	1.19%	1.19%	1.37%	72%	$256,100
(4.04)	—	—	$25.86	22.42%	1.20% ^(b)	1.19% ^(b)(c)	1.77%	63%	$295,231
(1.18)	—	—	$24.46	(9.76)%	1.14%	1.14% ^(d)	1.03%	44%	$259,553
(0.38)	0.00 ^(e)	0.00 ^(e)	$28.33	21.89%	1.16%	1.16% ^(d)	0.75%	42%	$366,081

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO112_12_E01_(05/15)

Columbia Acorn Select^SM

Summary of the Fund

Investment Objective

Columbia Acorn Select^SM (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 22 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class B	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	5.00% ^(b)	1.00% ^(c)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class B	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees	0.85%	0.85%	0.85%	0.85%	0.85%	0.85%	0.85%	0.85%
Distribution and/or service (12b-1) fees	0.25%	0.75%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.22%	0.55%	0.19%	0.10%	0.27%	0.15%	0.10%	0.19%
Total annual Fund operating expenses	1.32%	2.15%	2.04%	0.95%	1.12%	1.00%	0.95%	1.04%
Less: Fee waivers and/or expense reimbursements^(d)	(0.20%)	(0.20%)	(0.20%)	(0.20%)	(0.20%)	(0.20%)	(0.20%)	(0.20%)
Total annual Fund operating expenses after fee waivers and/or expense reimbursements	1.12%	1.95%	1.84%	0.75%	0.92%	0.80%	0.75%	0.84%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

(b)	This charge decreases over time.

(c)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.
(d)	Effective May 1, 2015, Columbia Wanger Asset Management, LLC (the Investment Manager) has contractually agreed to waive 0.20% of the advisory fee otherwise payable to it by the Fund through April 30, 2016. This arrangement may only be modified or amended with approval from all parties to the arrangement, including the Fund and the Investment Manager.

Example

■	you invest $10,000 in the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn Select^SM

Summary of the Fund (continued)

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$683	$951	$1,239	$2,057
Class B (assuming redemption of all shares at the end of the period)	$698	$954	$1,336	$2,256
Class B (assuming no redemption of shares)	$198	$654	$1,136	$2,256
Class C (assuming redemption of all shares at the end of the period)	$287	$620	$1,080	$2,353
Class C (assuming no redemption of shares)	$187	$620	$1,080	$2,353
Class I (whether or not shares are redeemed)	$ 77	$283	$ 506	$1,148
Class R4 (whether or not shares are redeemed)	$ 94	$336	$ 598	$1,345
Class R5 (whether or not shares are redeemed)	$ 82	$298	$ 533	$1,206
Class Y (whether or not shares are redeemed)	$ 77	$283	$ 506	$1,148
Class Z (whether or not shares are redeemed)	$ 86	$311	$ 555	$1,253

Portfolio Turnover

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 initial 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. Under normal circumstances, the Fund may invest in companies with market capitalizations above $20 billion at the time of initial investment, provided that immediately after that investment a majority of its net assets would be invested in companies whose market capitalizations were under $20 billion at the time of initial investment.

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 in a limited number of companies (generally between 30-60), offering the potential to provide above-average growth over time. In pursuit of the Fund’s objective, the portfolio managers may take advantage of the research and stock-picking capabilities of the Investment Manager to select investments that are “best ideas,” but need not do so and will generally concentrate the Fund’s investments in those sectors, companies, geographic regions or industries that the portfolio managers believe offer the most growth potential.

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

4	Prospectus 2015

Columbia Acorn Select^SM

Summary of the Fund (continued)

■	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.

Principal Risks

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

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.

Prospectus 2015

Columbia Acorn Select^SM

Summary of the Fund (continued)

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

6	Prospectus 2015

Columbia Acorn Select^SM

Summary of the Fund (continued)

Performance Information

Prospectus 2015

Columbia Acorn Select^SM

Summary of the Fund (continued)

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{2nd Quarter 2009}	_28.11%
	_Worst	_{4th Quarter 2008}	_-30.14%

*	Year to Date return as of March 31, 2015: 2.83%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class Z	11/23/1998
returns before taxes		2.47%	10.60%	7.33%
returns after taxes on distributions		-2.20%	7.98%	5.89%
returns after taxes on distributions and sale of Fund shares		5.17%	8.33%	5.93%
Class A returns before taxes	10/16/2000	-3.70%	8.98%	6.39%
Class B returns before taxes	10/16/2000	-2.60%	9.30%	6.31%
Class C returns before taxes	10/16/2000	0.63%	9.45%	6.19%
Class I returns before taxes	09/27/2010	2.49%	10.69%	7.38%
Class R4 returns before taxes	11/08/2012	2.39%	10.58%	7.32%
Class R5 returns before taxes	11/08/2012	2.50%	10.62%	7.34%
Class Y returns before taxes	11/08/2012	2.53%	10.64%	7.35%
S&P MidCap 400^® Index (reflects no deductions for fees, expenses or taxes)		9.77%	16.54%	9.71%
S&P 500^® Index (reflects no deductions for fees, expenses or taxes)		13.69%	15.45%	7.67%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Robert A. Chalupnik, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since 2011	2000
Matthew S. Szafranski, CFA	Portfolio Manager and Analyst	Co-manager since 2015	2008

8	Prospectus 2015

Columbia Acorn Select^SM

Summary of the Fund (continued)

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A, B* & C	All accounts other than IRAs	$2,000	$100
Classes A, B* & C	IRAs	$1,000	$100
Classes I, R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

*	Class B shares are generally closed to new and existing shareholders.

There is no minimum additional investment for any share class.

Tax Information

Payments to Broker-Dealers and Other Financial Intermediaries

Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund

Investment Objective

Columbia Acorn Select^SM (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

10	Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

experience greater risk and volatility relative to the benchmark. Because the Fund may invest in more than one company concentrated in a similar industry, sector or geographic region, the Fund may be even more concentrated than the number of companies it may hold would suggest.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

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.

12	Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries.

Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Investment Guidelines

Holding Other Kinds of Investments

Investing in Affiliated Funds

14	Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

Investing in Money Market Funds

Lending of Portfolio Securities

Investing Defensively

Portfolio Holdings Disclosure

Cybersecurity

Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

Use of Benchmarks

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Additional Information on Portfolio Turnover

Cash Flows

Understanding Annual Fund Operating Expenses

16	Prospectus 2015

Columbia Acorn Select^SM

More Information About the Fund (continued)

FUNDamentals

Other Expenses

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

Effective May 1, 2015, the Investment Manager has contractually agreed to waive 0.20% of the advisory fee otherwise payable to it by the Fund through April 30, 2016. When determining whether the Fund’s total expenses exceed the voluntary expense cap described below, the Fund’s net advisory fee, reflecting application of the 0.20% waiver, will be used to calculate the Fund’s total expenses. This arrangement may only be modified or amended with approval from all parties to the arrangement, including the Fund and the Investment Manager.

In addition, the Investment Manager has voluntarily agreed to reimburse expenses so that the Fund’s ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund’s investments in other investment companies, if any), after giving effect to any balance credits or overdraft charges from the Fund’s custodian, do not exceed the annual rates of:

Columbia Acorn Select
Class A	1.60%
Class B	2.10%
Class C	2.35%
Class I	1.25%
Class R4	1.35%
Class R5	1.30%
Class Y	1.25%
Class Z	1.35%

The Investment Manager or the Fund may modify or discontinue this arrangement on 30 days’ notice.

Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates and any predecessor firms that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

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Columbia Acorn Select^SM

More Information About the Fund (continued)

Board of Trustees

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

Primary Service Providers

The Investment Manager

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 0.85% of average daily net assets of the Fund. A discussion regarding the basis for the Board approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Effective May 1, 2015, the Investment Manager has contractually agreed to waive 0.20% of the advisory fee otherwise payable to it by the Fund through April 30, 2016. This arrangement may only be modified or amended with approval from all parties to the arrangement, including the Fund and the Investment Manager.

Portfolio Managers

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More Information About the Fund (continued)

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Robert A. Chalupnik, CFA	Portfolio Manager and Analyst	Co-manager or lead manager since 2011	2000
Matthew S. Szafranski, CFA	Portfolio Manager and Analyst	Co-manager since 2015	2008

Mr. Chalupnik has been associated with the Investment Manager or its predecessors as an investment professional since 1998 and has been a 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.

Mr. Szafranski has been associated with the Investment Manager or its predecessors as an investment professional since 1999 and has been a Vice President of the Trust since May 2015. Mr. Szafranski began his investment career in 1999 and earned a B.B.A from the University of Iowa and an M.B.A. from DePaul University.

The Administrator

Annual Administration Fee, as a % of Aggregate 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

The Transfer Agent

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Columbia Acorn Select^SM

More Information About the Fund (continued)

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

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

■

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

■

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More Information About the Fund (continued)

Certain Legal Matters

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Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

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Choosing a Share Class (continued)

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.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

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Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

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Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

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Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge

FUNDamentals

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 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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Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

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Choosing a Share Class (continued)

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

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Choosing a Share Class (continued)

Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

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Columbia Acorn Select^SM

Choosing a Share Class (continued)

FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

30	Prospectus 2015

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Choosing a Share Class (continued)

Front-End Sales Charge Waivers

CDSC Waivers

Repurchases

Restrictions and Changes in Terms and Conditions

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Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

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Choosing a Share Class (continued)

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Buying, Selling and Exchanging Shares

Share Price Determination

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

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

Business Days

34	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

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Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

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Buying, Selling and Exchanging Shares (continued)

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.

Opening an Account and Placing Orders

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Buying, Selling and Exchanging Shares (continued)

Accounts Established Directly with the Fund

Written Transactions

38	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

Telephone Transactions

Online Transactions

Wire Transactions

Electronic Funds Transfer

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Buying, Selling and Exchanging Shares (continued)

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

Class R Shares

40	Prospectus 2015

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Buying, Selling and Exchanging Shares (continued)

Class R4 Shares

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

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Buying, Selling and Exchanging Shares (continued)

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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

Class Z Shares Minimum Initial Investments

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

■

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

■

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Buying, Selling and Exchanging Shares (continued)

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

■	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.

■

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

■

■	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.

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Buying, Selling and Exchanging Shares (continued)

Systematic Investment Plan

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

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Buying, Selling and Exchanging Shares (continued)

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

Systematic Exchanges

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Buying, Selling and Exchanging Shares (continued)

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

■

■	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 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).

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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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

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Distributions and Taxes (continued)

Taxes

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

■

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Distributions and Taxes (continued)

■

FUNDamentals

Taxes

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Financial Highlights

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Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations			Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Reimbursement from affiliate	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$25.57	(0.14)	0.64	—	0.50	—	(5.04)
Year Ended December 31, 2013	$24.72	(0.15)	7.92	—	7.77	(0.07)	(6.85)
Year Ended December 31, 2012	$22.95	0.03	3.78	—	3.81	—	(2.04)
Year Ended December 31, 2011	$27.94	(0.15)	(4.46)	—	(4.61)	(0.38)	—
Year Ended December 31, 2010	$22.81	(0.18)	5.31	—	5.13	—	—
Class B
Year Ended December 31, 2014	$22.81	(0.31)	0.57	—	0.26	—	(5.04)
Year Ended December 31, 2013	$22.75	(0.33)	7.24	—	6.91	—	(6.85)
Year Ended December 31, 2012	$21.40	(0.15)	3.54	—	3.39	—	(2.04)
Year Ended December 31, 2011	$26.06	(0.30)	(4.13)	—	(4.43)	(0.23)	—
Year Ended December 31, 2010	$21.41	(0.31)	4.96	—	4.65	—	—
Class C
Year Ended December 31, 2014	$22.46	(0.28)	0.55	—	0.27	—	(5.04)
Year Ended December 31, 2013	$22.48	(0.32)	7.15	—	6.83	—	(6.85)
Year Ended December 31, 2012	$21.20	(0.14)	3.46	—	3.32	—	(2.04)
Year Ended December 31, 2011	$25.83	(0.32)	(4.12)	—	(4.44)	(0.19)	—
Year Ended December 31, 2010	$21.25	(0.34)	4.92	—	4.58	—	—
Class I
Year Ended December 31, 2014	$26.81	(0.05)	0.66	—	0.61	—	(5.04)
Year Ended December 31, 2013	$25.63	(0.06)	8.25	—	8.19	(0.16)	(6.85)
Year Ended December 31, 2012	$23.65	0.23	3.79	—	4.02	—	(2.04)
Year Ended December 31, 2011	$28.74	(0.03)	(4.59)	—	(4.62)	(0.47)	—
Year Ended December 31, 2010^(e)	$24.74	0.01	3.99	—	4.00	—	—
Class R4
Year Ended December 31, 2014	$27.20	(0.10)	0.69	—	0.59	—	(5.04)
Year Ended December 31, 2013	$25.92	(0.06)	8.32	—	8.26	(0.13)	(6.85)
Year Ended December 31, 2012^(g)	$25.91	0.00 ^(h)	1.52	—	1.52	—	(1.51)
Class R5
Year Ended December 31, 2014	$27.20	(0.07)	0.69	—	0.62	—	(5.04)
Year Ended December 31, 2013	$25.93	(0.04)	8.31	—	8.27	(0.15)	(6.85)
Year Ended December 31, 2012⁽ⁱ⁾	$25.91	0.00 ^(h)	1.53	—	1.53	—	(1.51)
Class Y
Year Ended December 31, 2014	$27.27	(0.06)	0.69	—	0.63	—	(5.04)
Year Ended December 31, 2013	$25.98	(0.03)	8.34	—	8.31	(0.17)	(6.85)
Year Ended December 31, 2012^(j)	$25.96	0.01	1.52	—	1.53	—	(1.51)
Class Z
Year Ended December 31, 2014	$26.72	(0.08)	0.68	—	0.60	—	(5.04)
Year Ended December 31, 2013	$25.57	(0.07)	8.21	—	8.14	(0.14)	(6.85)
Year Ended December 31, 2012	$23.62	0.11	3.88	—	3.99	—	(2.04)
Year Ended December 31, 2011	$28.73	(0.07)	(4.58)	0.00 ^(h)	(4.65)	(0.46)	—
Year Ended December 31, 2010	$23.38	(0.10)	5.45	—	5.35	—	—

Notes to Financial Highlights

(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(b)	Ratios include line of credit interest expense which is less than 0.01%.

(c)	The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(d)	Had the Investment Manager and/or its affiliates not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(e)	Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(f)	Annualized.

(g)	Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(h)	Rounds to zero.

(i)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(j)	Class Y shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(k)	During the year ended December 31, 2011, the Fund received a reimbursement from an affiliate. Had the Fund not received this payment, the total return would have been lower by 0.01%.

52	Prospectus 2015

Columbia Acorn Select^SM

Financial Highlights (continued)

Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return	Total gross expenses ^(a)	Total net expenses ^(a)	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

(5.04)	$21.03	2.17%	1.32%	1.32%	(0.58)%	17%	$264,234
(6.92)	$25.57	33.77%	1.31% ^(b)	1.31% ^(b)	(0.54)%	20%	$333,193
(2.04)	$24.72	16.87%	1.31% ^(b)	1.31% ^(b)(c)	0.13%	15%	$271,628
(0.38)	$22.95	(16.65)%	1.28%	1.28% ^(c)	(0.57)%	21%	$340,325
—	$27.94	22.49%	1.28%	1.28% ^(c)	(0.73)%	28%	$555,263

(5.04)	$18.03	1.35% ^(d)	2.14%	2.10%	(1.40)%	17%	$1,014
(6.85)	$22.81	32.81% ^(d)	2.05% ^(b)	2.03% ^(b)	(1.32)%	20%	$2,938
(2.04)	$22.75	16.11%	1.91% ^(b)	1.90% ^(b)(c)	(0.62)%	15%	$9,938
(0.23)	$21.40	(17.11)%	1.88%	1.88% ^(c)	(1.21)%	21%	$26,126
—	$26.06	21.72%	1.92%	1.92% ^(c)	(1.39)%	28%	$72,203

(5.04)	$17.69	1.42%	2.04%	2.04%	(1.30)%	17%	$48,591
(6.85)	$22.46	32.85%	2.04% ^(b)	2.04% ^(b)	(1.28)%	20%	$61,537
(2.04)	$22.48	15.93%	2.07% ^(b)	2.06% ^(b)(c)	(0.59)%	15%	$57,309
(0.19)	$21.20	(17.27)%	2.05%	2.05% ^(c)	(1.34)%	21%	$62,887
—	$25.83	21.55%	2.07%	2.07% ^(c)	(1.52)%	28%	$98,445

(5.04)	$22.38	2.49%	0.94%	0.94%	(0.20)%	17%	$18,718
(7.01)	$26.81	34.31%	0.94% ^(b)	0.94% ^(b)	(0.21)%	20%	$13,660
(2.04)	$25.63	17.26%	0.96% ^(b)	0.95% ^(b)(c)	0.89%	15%	$39,054
(0.47)	$23.65	(16.25)%	0.92%	0.92% ^(c)	(0.12)%	21%	$10,944
—	$28.74	16.17%	0.91% ^(f)	0.91% ^(c)(f)	0.18% ^(f)	28%	$7,832

(5.04)	$22.75	2.39%	1.12%	1.12%	(0.37)%	17%	$1,193
(6.98)	$27.20	34.16%	1.02% ^(b)	1.02% ^(b)	(0.20)%	20%	$1,383
(1.51)	$25.92	5.92%	1.07% ^(f)	1.06% ^(c)(f)	0.02% ^(f)	15%	$15

(5.04)	$22.78	2.50%	1.00%	1.00%	(0.26)%	17%	$10,697
(7.00)	$27.20	34.21%	0.97% ^(b)	0.97% ^(b)	(0.13)%	20%	$11,996
(1.51)	$25.93	5.96%	0.99% ^(f)	0.99% ^(c)(f)	0.08% ^(f)	15%	$3

(5.04)	$22.86	2.53%	0.95%	0.95%	(0.22)%	17%	$3,644
(7.02)	$27.27	34.30%	0.93% ^(b)	0.93% ^(b)	(0.09)%	20%	$4,847
(1.51)	$25.98	5.94%	0.92% ^(f)	0.92% ^(c)(f)	0.15% ^(f)	15%	$3

(5.04)	$22.28	2.47%	1.04%	1.04%	(0.30)%	17%	$318,487
(6.99)	$26.72	34.16%	1.02% ^(b)	1.02% ^(b)	(0.26)%	20%	$431,990
(2.04)	$25.57	17.15%	1.03% ^(b)	1.03% ^(b)(c)	0.40%	15%	$587,678
(0.46)	$23.62	(16.37)% ^(k)	0.97%	0.97% ^(c)	(0.28)%	21%	$850,338
—	$28.73	22.88%	0.97%	0.97% ^(c)	(0.41)%	28%	$1,549,112

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO113_12_E01_(05/15)

Columbia Acorn USA®

Summary of the Fund

Investment Objective

Columbia Acorn USA^® (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 17 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class B	Class C	Classes I, R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	5.00% ^(b)	1.00% ^(c)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class B	Class C	Class I	Class R4	Class R5	Class Y	Class Z
Management fees	0.86%	0.86%	0.86%	0.86%	0.86%	0.86%	0.86%	0.86%
Distribution and/or service (12b-1) fees	0.25%	0.75%	1.00%	0.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.23%	0.65%	0.14%	0.08%	0.21%	0.13%	0.08%	0.22%
Total annual Fund operating expenses	1.34%	2.26%	2.00%	0.94%	1.07%	0.99%	0.94%	1.08%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

(b)	This charge decreases over time.

(c)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

Example

■	you invest $10,000 in the applicable class of Fund shares 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 Annual Fund Operating Expenses table above.

Prospectus 2015

Columbia Acorn USA®

Summary of the Fund (continued)

Although your actual costs may be higher or lower, based on the assumptions listed above, your costs would be:

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$704	$ 975	$1,267	$2,095
Class B (assuming redemption of all shares at the end of the period)	$729	$1,006	$1,410	$2,363
Class B (assuming no redemption of shares)	$229	$ 706	$1,210	$2,363
Class C (assuming redemption of all shares at the end of the period)	$303	$ 627	$1,078	$2,327
Class C (assuming no redemption of shares)	$203	$ 627	$1,078	$2,327
Class I (whether or not shares are redeemed)	$ 96	$ 300	$ 520	$1,155
Class R4 (whether or not shares are redeemed)	$109	$ 340	$ 590	$1,306
Class R5 (whether or not shares are redeemed)	$101	$ 315	$ 547	$1,213
Class Y (whether or not shares are redeemed)	$ 96	$ 300	$ 520	$1,155
Class Z (whether or not shares are redeemed)	$110	$ 343	$ 595	$1,317

Portfolio Turnover

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount any borrowings for investment purposes) in U.S. companies.

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

4	Prospectus 2015

Columbia Acorn USA®

Summary of the Fund (continued)

Principal Risks

Active Management Risk. The Investment Manager’s active management of the Fund could cause the Fund to underperform its benchmark index and/or other funds with similar investment objectives.

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

Performance Information

Prospectus 2015

Columbia Acorn USA®

Summary of the Fund (continued)

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{3rd Quarter 2009}	_23.55%
	_Worst	_{4th Quarter 2008}	_-27.96%

*	Year to Date return as of March 31, 2015: 5.12%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class Z	09/04/1996
returns before taxes		3.61%	13.88%	7.62%
returns after taxes on distributions		-0.52%	12.21%	6.57%
returns after taxes on distributions and sale of Fund shares		5.33%	11.17%	6.22%
Class A returns before taxes	10/16/2000	-2.58%	12.23%	6.69%
Class B returns before taxes	10/16/2000	-1.74%	12.50%	6.59%
Class C returns before taxes	10/16/2000	1.85%	12.76%	6.52%
Class I returns before taxes	09/27/2010	3.80%	14.00%	7.68%
Class R4 returns before taxes	11/08/2012	3.60%	13.89%	7.63%
Class R5 returns before taxes	11/08/2012	3.68%	13.91%	7.64%
Class Y returns before taxes	11/08/2012	3.76%	13.94%	7.65%
Russell 2000 Index (reflects no deductions for fees, expenses or taxes)		4.89%	15.55%	7.77%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Robert A. Mohn, CFA	Portfolio Manager, Analyst and Domestic Chief Investment Officer of the Investment Manager	Lead manager since inception in 1996	1996
William J. Doyle, CFA	Portfolio Manager and Analyst	Co-manager since 2014	2006

6	Prospectus 2015

Columbia Acorn USA®

Summary of the Fund (continued)

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A, B* & C	All accounts other than IRAs	$2,000	$100
Classes A, B* & C	IRAs	$1,000	$100
Classes I, R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

*	Class B shares are generally closed to new and existing shareholders.

There is no minimum additional investment for any share class.

Tax Information

Payments to Broker-Dealers and Other Financial Intermediaries

Prospectus 2015

Columbia Acorn USA®

More Information About the Fund

Investment Objective

Columbia Acorn USA® (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

Under normal circumstances, the Fund invests at least 80% of its net assets (including the amount any borrowings for investment purposes) in U.S. companies.

The Investment Manager typically seeks companies with:

■	A strong business franchise that offers growth potential.

■	Products and services in which the company has a competitive advantage.

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

Principal Risks

Market Risk. Market risk refers to the possibility that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

8	Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Investment Guidelines

Holding Other Kinds of Investments

Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

Investing in Affiliated Funds

Investing in Money Market Funds

Lending of Portfolio Securities

Investing Defensively

10	Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

on futures for as long a period as deemed necessary when the Investment Manager determines that a temporary defensive position is advisable or necessary to meet anticipated redemption requests, or for other reasons. The Fund may not achieve its investment objective, and the Fund’s performance may be adversely affected, while it is investing defensively.

Portfolio Holdings Disclosure

Cybersecurity

Use of Benchmarks

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

Additional Information on Portfolio Turnover

Cash Flows

Understanding Annual Fund Operating Expenses

FUNDamentals

Other Expenses

12	Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates and any predecessor firms that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

Board of Trustees

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

Primary Service Providers

The Investment Manager

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 approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

Portfolio Managers

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Robert A. Mohn, CFA	Portfolio Manager, Analyst and Domestic Chief Investment Officer of the Investment Manager	Lead manager since inception in 1996	1996
William J. Doyle, CFA	Portfolio Manager and Analyst	Co-manager since 2014	2006

Mr. Doyle has been associated with the Investment Manager or its predecessors as an investment professional since 2006 and has been a Vice President of the Trust since 2014. Mr. Doyle began his investment management career in 1987 and earned a B.S. and a B.A. from Illinois State University and an M.B.A from Loyola University of Chicago.

The Administrator

Annual Administration Fee, as a % of Aggregate 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

The Transfer Agent

14	Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

financial intermediaries for providing certain shareholder services. The Fund generally pays the Transfer Agent a per account fee for each open account and compensates the Transfer Agent for certain out-of-pocket expenses. In addition, subject to certain limitations, the Fund compensates the Transfer Agent for payments made 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. The Transfer Agent is contractually obligated to oversee such intermediaries for the purpose of reasonably assuring their compliance with applicable law and the terms of their agreements to provide the shareholder services. For more information about Shareholder Services fees, see Choosing a Share Class — Selling Agent Compensation.

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

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

■

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

■

Prospectus 2015

Columbia Acorn USA®

More Information About the Fund (continued)

Certain Legal Matters

16	Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

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.

Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

18	Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

20	Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge

FUNDamentals

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 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).

Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Class A Shares — Front-End Sales Charge — Breakpoint Schedule
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

22	Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

24	Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Front-End Sales Charge Waivers

CDSC Waivers

Repurchases

Restrictions and Changes in Terms and Conditions

26	Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

Prospectus 2015

Columbia Acorn USA®

Choosing a Share Class (continued)

28	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares

Share Price Determination

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

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

Business Days

Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

30	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

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.

Opening an Account and Placing Orders

32	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Accounts Established Directly with the Fund

Written Transactions

Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Telephone Transactions

Online Transactions

Wire Transactions

Electronic Funds Transfer

34	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

Class R Shares

Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Class R4 Shares

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

36	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

Class Z Shares Minimum Initial Investments

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

■

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

■

Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

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

■	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.

■

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

■

■	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.

38	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

Systematic Investment Plan

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

Systematic Exchanges

40	Prospectus 2015

Columbia Acorn USA®

Buying, Selling and Exchanging Shares (continued)

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

■

■	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 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).

Prospectus 2015

Columbia Acorn USA®

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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

Prospectus 2015

Columbia Acorn USA®

Distributions and Taxes (continued)

Taxes

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

■

44	Prospectus 2015

Columbia Acorn USA®

Distributions and Taxes (continued)

■

FUNDamentals

Taxes

Prospectus 2015

Columbia Acorn USA®

Financial Highlights

Prospectus 2015

Columbia Acorn USA®

Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations		Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income (loss)	Net realized and unrealized gain (loss)	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$34.15	(0.20)	1.22	1.02	—	(6.04)
Year Ended December 31, 2013	$28.21	(0.15)	9.09	8.94	—	(3.00)
Year Ended December 31, 2012	$25.94	0.02	4.73	4.75	(0.11)	(2.37)
Year Ended December 31, 2011	$27.54	(0.22)	(1.21)	(1.43)	—	(0.17)
Year Ended December 31, 2010	$22.43	(0.15)	5.26	5.11	—	—
Class B
Year Ended December 31, 2014	$30.70	(0.46)	1.07	0.61	—	(6.04)
Year Ended December 31, 2013	$25.81	(0.39)	8.28	7.89	—	(3.00)
Year Ended December 31, 2012	$23.98	(0.19)	4.39	4.20	—	(2.37)
Year Ended December 31, 2011	$25.60	(0.37)	(1.08)	(1.45)	—	(0.17)
Year Ended December 31, 2010	$20.99	(0.30)	4.91	4.61	—	—
Class C
Year Ended December 31, 2014	$30.33	(0.37)	1.06	0.69	—	(6.04)
Year Ended December 31, 2013	$25.49	(0.33)	8.17	7.84	—	(3.00)
Year Ended December 31, 2012	$23.72	(0.16)	4.30	4.14	—	(2.37)
Year Ended December 31, 2011	$25.39	(0.39)	(1.11)	(1.50)	—	(0.17)
Year Ended December 31, 2010	$20.84	(0.31)	4.86	4.55	—	—
Class I
Year Ended December 31, 2014	$35.99	(0.06)	1.30	1.24	—	(6.04)
Year Ended December 31, 2013	$29.47	(0.02)	9.54	9.52	—	(3.00)
Year Ended December 31, 2012	$27.00	(0.10)	5.16	5.06	(0.22)	(2.37)
Year Ended December 31, 2011	$28.56	(0.14)	(1.25)	(1.39)	—	(0.17)
Year Ended December 31, 2010^(d)	$24.24	(0.03)	4.35	4.32	—	—
Class R4
Year Ended December 31, 2014	$36.55	(0.11)	1.30	1.19	—	(6.04)
Year Ended December 31, 2013	$29.92	0.00 ^(f)	9.63	9.63	—	(3.00)
Year Ended December 31, 2012^(g)	$30.06	0.06	2.28	2.34	(0.16)	(2.32)
Class R5
Year Ended December 31, 2014	$36.53	(0.06)	1.28	1.22	—	(6.04)
Year Ended December 31, 2013	$29.90	0.02	9.61	9.63	—	(3.00)
Year Ended December 31, 2012^(h)	$30.06	0.07	2.27	2.34	(0.18)	(2.32)
Class Y
Year Ended December 31, 2014	$36.59	(0.07)	1.32	1.25	—	(6.04)
Year Ended December 31, 2013	$29.93	0.02	9.64	9.66	—	(3.00)
Year Ended December 31, 2012⁽ⁱ⁾	$30.10	0.07	2.27	2.34	(0.19)	(2.32)
Class Z
Year Ended December 31, 2014	$35.90	(0.12)	1.29	1.17	—	(6.04)
Year Ended December 31, 2013	$29.45	(0.07)	9.52	9.45	—	(3.00)
Year Ended December 31, 2012	$26.98	0.11	4.92	5.03	(0.19)	(2.37)
Year Ended December 31, 2011	$28.56	(0.14)	(1.27)	(1.41)	—	(0.17)
Year Ended December 31, 2010	$23.19	(0.08)	5.45	5.37	—	—

Notes to Financial Highlights

(a)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of any other funds in which it invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(b)	Ratios include line of credit interest expense which is less than 0.01%.

(c)	The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(d)	Class I shares commenced operations on September 27, 2010. Per share data and total return reflect activity from that date.

(e)	Annualized.

(f)	Rounds to zero.

(g)	Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(h)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(i)	Class Y shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

48	Prospectus 2015

Columbia Acorn USA®

Financial Highlights (continued)

Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return	Total gross expenses ^(a)	Total net expenses ^(a)	Net investment income (loss)	Portfolio turnover rate	Net assets, end of period (000s)

(6.04)	$29.13	3.35%	1.33%	1.33%	(0.60)%	12%	$148,089
(3.00)	$34.15	32.34%	1.32%	1.32%	(0.46)%	17%	$201,559
(2.48)	$28.21	18.67%	1.32% ^(b)	1.32% ^(b)(c)	0.08%	14%	$152,164
(0.17)	$25.94	(5.21)%	1.30%	1.30% ^(c)	(0.78)%	20%	$167,038
—	$27.54	22.78%	1.30%	1.30% ^(c)	(0.64)%	32%	$214,097

(6.04)	$25.27	2.37%	2.26%	2.26%	(1.55)%	12%	$234
(3.00)	$30.70	31.28%	2.15%	2.15%	(1.33)%	17%	$567
(2.37)	$25.81	17.87%	1.99% ^(b)	1.99% ^(b)(c)	(0.71)%	14%	$1,056
(0.17)	$23.98	(5.68)%	1.92%	1.92% ^(c)	(1.42)%	20%	$2,253
—	$25.60	21.96%	1.98%	1.98% ^(c)	(1.37)%	32%	$9,222

(6.04)	$24.98	2.67%	2.00%	2.00%	(1.26)%	12%	$36,476
(3.00)	$30.33	31.47%	2.00%	2.00%	(1.14)%	17%	$40,395
(2.37)	$25.49	17.82%	2.05% ^(b)	2.05% ^(b)(c)	(0.61)%	14%	$31,410
(0.17)	$23.72	(5.92)%	2.05%	2.05% ^(c)	(1.53)%	20%	$30,584
—	$25.39	21.83%	2.08%	2.08% ^(c)	(1.41)%	32%	$36,101

(6.04)	$31.19	3.80%	0.88%	0.88%	(0.17)%	12%	$2
(3.00)	$35.99	32.93%	0.90%	0.90%	(0.04)%	17%	$4
(2.59)	$29.47	19.10%	0.96%	0.96% ^(c)	(0.33)%	14%	$3
(0.17)	$27.00	(4.88)%	0.94%	0.94% ^(c)	(0.47)%	20%	$2,635
—	$28.56	17.82%	0.94% ^(e)	0.94% ^(c)(e)	(0.35)% ^(e)	32%	$28,993

(6.04)	$31.70	3.60%	1.07%	1.07%	(0.32)%	12%	$7,952
(3.00)	$36.55	32.80%	1.00%	1.00%	0.01%	17%	$6,441
(2.48)	$29.92	8.06%	1.14% ^(b)(e)	1.14% ^(b)(c)(e)	1.51% ^(e)	14%	$15

(6.04)	$31.71	3.68%	0.99%	0.99%	(0.17)%	12%	$36,689
(3.00)	$36.53	32.83%	0.97%	0.97%	0.06%	17%	$6,068
(2.50)	$29.90	8.06%	1.12% ^(e)	1.12% ^(c)(e)	1.53% ^(e)	14%	$2

(6.04)	$31.80	3.76%	0.93%	0.93%	(0.19)%	12%	$35,551
(3.00)	$36.59	32.89%	0.93%	0.93%	0.07%	17%	$48,479
(2.51)	$29.93	8.07%	1.04% ^(e)	1.04% ^(c)(e)	1.62% ^(e)	14%	$2

(6.04)	$31.03	3.61%	1.08%	1.08%	(0.34)%	12%	$1,132,223
(3.00)	$35.90	32.72%	1.06%	1.06%	(0.20)%	17%	$1,496,775
(2.56)	$29.45	18.98%	1.07% ^(b)	1.07% ^(b)(c)	0.36%	14%	$1,415,442
(0.17)	$26.98	(4.95)%	1.00%	1.00% ^(c)	(0.48)%	20%	$1,355,934
—	$28.56	23.16%	1.01%	1.01% ^(c)	(0.34)%	32%	$1,410,133

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO115_12_E01_(05/15)

Columbia Thermostat Fund^SM

Summary of the Fund

Investment Objective

Columbia Thermostat Fund^SM (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. You may qualify for sales charge discounts if you and members of your immediate family invest, or agree to invest in the future, at least $50,000 in certain classes of shares of eligible funds distributed by Columbia Management Investment Distributors, Inc. (the Distributor). More information about these and other discounts is available from your financial intermediary, and can be found in the Choosing a Share Class section beginning on page 40 of the Fund’s prospectus and in Appendix S to the Statement of Additional Information (SAI) under Sales Charge Waivers beginning on page S-1.

Shareholder Fees (fees paid directly from your investment)
	Class A	Class B	Class C	Classes R4, R5, Y and Z
Maximum sales charge (load) imposed on purchases (as a % of offering price)	5.75%	None	None	None
Maximum deferred sales charge (load) imposed on redemptions (as a % of the lower of the original purchase price or current net asset value)	1.00% ^(a)	5.00% ^(b)	1.00% ^(c)	None

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
	Class A	Class B	Class C	Class R4	Class R5	Class Y	Class Z
Management fees	0.10%	0.10%	0.10%	0.10%	0.10%	0.10%	0.10%
Distribution and/or service (12b-1) fees	0.25%	0.75%	1.00%	0.00%	0.00%	0.00%	0.00%
Other expenses	0.16%	0.31%	0.16%	0.16%	0.14%	0.09%	0.15%
Acquired fund fees and expenses	0.52%	0.52%	0.52%	0.52%	0.52%	0.52%	0.52%
Total annual Fund operating expenses^(d)	1.03%	1.68%	1.78%	0.78%	0.76%	0.71%	0.77%
Fee waivers and/or expense reimbursements^(e)	(0.01%)	(0.16%)	(0.01%)	(0.01%)	0.00%	0.00%	0.00%
Total annual Fund operating expenses after fee waivers and/or expense reimbursements	1.02%	1.52%	1.77%	0.77%	0.76%	0.71%	0.77%

(a)	This charge is imposed on certain investments of between $1 million and $50 million redeemed within 18 months after purchase, as follows: 1.00% if redeemed within 12 months after purchase, and 0.50% if redeemed more than 12, but less than 18, months after purchase, with certain limited exceptions.

(b)	This charge decreases over time.

(c)	This charge applies to redemptions within one year after purchase, with certain limited exceptions.

(d)

“Total annual Fund operating expenses” include acquired fund (Portfolio Fund) fees and expenses (expenses the Fund incurs indirectly through its investments in other funds) and may be higher than “Total Net Expenses” shown in the Financial Highlights section of this prospectus because “Total Net Expenses” do not include Portfolio Fund (acquired fund) fees and expenses.

(e)

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 transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund’s investment in the Portfolio Funds (acquired funds)), do not exceed the annual rates of 0.50% for Class A shares, 1.00% for Class B shares, 1.25% for Class C shares, 0.25% for Class R4 shares, 0.24% for Class R5 shares, 0.19% for Class Y shares and 0.25% for Class Z shares, through April 30, 2016. This arrangement may only be modified or amended with approval from all parties to the arrangement, including the Fund and the Investment Manager.

Example

■	you invest $10,000 in the applicable class of Fund shares for the periods indicated,
■	your investment has a 5% return each year, and

Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

■	the Fund’s total annual operating expenses remain the same as shown in the Annual Fund Operating Expenses table above.

	1 year	3 years	5 years	10 years
Class A (whether or not shares are redeemed)	$673	$883	$1,110	$1,761
Class B (assuming redemption of all shares at the end of the period)	$655	$814	$1,098	$1,801
Class B (assuming no redemption of shares)	$155	$514	$ 898	$1,801
Class C (assuming redemption of all shares at the end of the period)	$280	$559	$ 964	$2,094
Class C (assuming no redemption of shares)	$180	$559	$ 964	$2,094
Class R4 (whether or not shares are redeemed)	$ 79	$248	$ 432	$ 965
Class R5 (whether or not shares are redeemed)	$ 78	$243	$ 422	$ 942
Class Y (whether or not shares are redeemed)	$ 73	$227	$ 395	$ 883
Class Z (whether or not shares are redeemed)	$ 79	$246	$ 428	$ 954

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 95% of the average value of its portfolio.

Principal Investment Strategies

The Fund is primarily managed as a fund that invests in other funds (i.e., a “fund-of-funds”) that seeks to achieve its investment objective by investing its assets among a selected group of underlying stock and bond mutual funds for which Columbia Wanger Asset Management, LLC, the Fund’s investment adviser (the Investment Manager) or its affiliates, including Columbia Management Investment Advisers, LLC, serves as investment adviser or principal underwriter (the Portfolio Funds). Under normal circumstances, the Fund allocates at least 95% of its net assets (stock/bond assets) among the 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 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.

4	Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

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 market and the portions of the bond market it believes will preserve capital and generate returns. 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 will fluctuate significantly and provide modest to no secular growth for many years.

The Fund invests its stock/bond assets among the Portfolio Funds according to an asset allocation table. The Investment Manager calibrates the allocation table such that stock percentages vary inversely with price-to-earnings ratios on “normalized” (long-term) earnings. Within a range of 10% to 90%, stock percentages rise towards maximum allocations as such price-to-earnings ratios fall towards historical lows, and stock percentages fall as such price-to-earnings ratios rise towards historical highs.

The Fund’s 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 2225	10%	90%
over 2150 – 2225	15%	85%
over 2075 – 2150	20%	80%
over 2000 – 2075	25%	75%
over 1925 – 2000	30%	70%
over 1850 – 1925	35%	65%
over 1775 – 1850	40%	60%
over 1700 – 1775	45%	55%
over 1625 – 1700	50%	50%
over 1550 – 1625	55%	45%
over 1475 – 1550	60%	40%
over 1400 – 1475	65%	35%
over 1325 – 1400	70%	30%
over 1250 – 1325	75%	25%
over 1175 – 1250	80%	20%
over 1100 – 1175	85%	15%
1100 and under	90%	10%

Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

best interest of shareholders. The second exception is 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 1680	50% stocks, 50% bonds
Dec. 1	The S&P 500^® goes to 1701	rebalance 45% stocks, 55% bonds
Dec. 6	The S&P 500^® drops back to 1690	no reversal for 31 days
Jan. 2	The S&P 500^® is at 1650	rebalance 50% stocks, 50% bonds
Jan. 20	The S&P 500^® drops to 1620	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 1630	no reversal for 31 days
Feb. 20	The S&P 500^® is at 1640	rebalance 50% stocks, 50% bonds

The following table shows the seven stock Portfolio Funds and four 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 Asset Within Asset Classes
	Type of Fund	Allocation
Stock Funds
Columbia Acorn^® Fund	Small/Mid-cap growth	10%
Columbia Acorn International^®	Small/Mid-cap international growth	20%
Columbia Acorn Select^SM	Mid-cap growth	10%
Columbia Contrarian Core Fund	Large-cap blend	20%
Columbia Dividend Income Fund	Large-cap value	20%
Columbia Large Cap Enhanced Core Fund	Large-cap blend	10%
Columbia Select Large Cap Growth Fund	Large-cap growth	10%

6	Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

Allocation of Stock/Bond Asset Within Asset Classes
	Type of Fund	Allocation
Total		100%

Bond Funds	Type of Fund	Allocation
Columbia Income Opportunities Fund	High-yield bond	20%
Columbia Intermediate Bond Fund	Intermediate-term bond	20%
Columbia Short Term Bond Fund	Short term bond	40%
Columbia U.S. Government Mortgage Fund	Government bond	20%
Total		100%

See the Portfolio Funds Summary section of this prospectus for information about the Portfolio Funds’ investment objectives and principal investment strategies.

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

An investment in the Fund involves risk, including general risks relating to the investment in the Fund based on its investment process and its "fund-of-funds" structure, as well as specific risks related to the individual Portfolio Funds, including those described below. There is no assurance that the Fund will achieve its investment objective and you may lose money. The value of the Fund’s holdings may decline, and the Fund’s net asset value (NAV) and share price may go down.

Allocation Risk. The Investment Manager uses an asset allocation strategy in pursuing the Fund’s 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 and/or strategies, or that the investments themselves will not produce the returns expected.

Fund-of-Funds Risk. Determinations regarding asset classes or underlying funds and the Fund’s allocations thereto may not successfully achieve the Fund’s investment objective, in whole or in part. The ability of the Fund to realize its investment objective will depend, in large part, on the extent to which the underlying funds realize their investment objective. There is no guarantee that the underlying funds will achieve their respective investment objectives. The Fund is exposed to the same risks as the underlying funds in direct proportion to the allocation of its assets among the underlying funds. By investing in a combination of underlying funds, the Fund has exposure to the risks of many areas of the market. The performance of underlying funds could be adversely affected if other entities that invest in the same underlying funds make relatively large investments or redemptions in such underlying funds. The Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of each underlying fund are shared by its investors, redemptions by other investors in an

Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

underlying fund could result in decreased economies of scale and increased operating expenses for such fund. The Investment Manager may have potential conflicts of interest in selecting affiliated funds over unaffiliated funds for investment by the Fund, and may also face potential conflicts of interest in selecting affiliated funds, because the fees the Investment Manager receives from some underlying funds may be higher than the fees paid by other underlying funds. Further, because of the Investment Manager’s confidence in its own strategies, investment philosophy and capacities, it will, in selecting underlying funds, at times prefer a fund in the Columbia Acorn Family of Funds over alternative investments. There can be no assurance, however, that a fund in the Columbia Acorn Family of Funds selected for inclusion in Columbia Thermostat Fund’s portfolio will, in fact, outperform similar funds managed by the Investment Manager’s affiliates.

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 or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. An investment in the Fund could lose money over short or long periods. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility.

Interest Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt securities tend to fall, and if interest rates fall, the values of debt securities tend to rise. Changes in the value of a debt security usually will not affect the amount of income the Fund receives from it but will usually affect the value of the Fund's shares. In general, the longer the maturity or duration of a debt security, the greater its sensitivity to changes in interest rates. Interest rate declines also may increase prepayments of debt obligations, which, in turn, would increase prepayment risk. Similarly, a period of rising interest rates may negatively impact the Fund’s performance. Actions by governments and central banking authorities can result in increases in interest rates. Such actions may negatively affect the value of fixed-income securities held by the Fund, resulting in a negative impact on the Fund's performance and NAV. Securities with floating interest rates are typically less sensitive to interest rate changes, but may decline in value if their interest rates do not rise as much as interest rates in general. Because rates on certain floating rate loans and other debt securities reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause fluctuations in the Fund’s NAV.

High-Yield Securities Risk. Securities rated below investment grade (commonly called “high-yield” or “junk” bonds) and unrated securities of comparable quality expose the Fund to a greater risk of loss of principal and income than a fund that invests solely or primarily in investment grade securities. In addition, these investments have greater price fluctuations, are less liquid and are more likely to experience a default than higher-rated securities. High-yield securities are considered to be predominantly speculative with respect to the issuer’s capacity to pay interest and repay principal.

8	Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

value of these investments to rise to the portfolio manager’s perceived 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. Growth securities typically trade at a higher multiple of earnings than other types of equity securities. Accordingly, the market values of growth securities may never reach their expected market value and may decline in price. 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.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. Foreign securities subject the Fund to the risks associated with investing in the particular country of an issuer, including the political, regulatory, economic, social, diplomatic and other conditions or events occurring in the country or region, as well as risks associated with less developed custody and settlement practices. Foreign securities may be more volatile and less liquid than securities of U.S. companies, and are subject to the risks associated with potential imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar, particularly to the extent the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar.

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 foreign sub-custodians. Some countries have limited governmental oversight and regulation, 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. As a result, there is a risk that the security will not be delivered to the Fund or that payment will not be received. 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.

Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

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 be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities 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.

Derivatives Risk. Losses involving derivative instruments may be substantial, because a relatively small movement in the price of an underlying security, instrument, commodity, currency or index may result in a substantial loss for the Fund. In addition to the potential for increased losses, the use of derivative instruments may lead to increased volatility for the Fund. Derivative investments will typically increase the Fund’s exposure to principal risks to which it is otherwise exposed, and may expose the Fund to additional risks, including correlation risk, counterparty risk, hedging risk, leverage risk and/or liquidity risk.

Convertible Securities Risk. Convertible securities 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, and are thus subject to market risk. The Fund may also be forced to convert a convertible security at an inopportune time, which may decrease the Fund’s return.

10	Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk. When purchasing mortgage-backed securities in the “to be announced” (TBA) market (MBS TBAs), the seller agrees to deliver mortgage-backed securities for an agreed upon price on an agreed upon date, but may make no guarantee as to the specific securities to be delivered. In lieu of taking delivery of mortgage-backed securities, the Fund could enter into dollar rolls, which are transactions in which the Fund sells securities to a counterparty and simultaneously agrees to purchase those or similar securities in the future at a predetermined price. Dollar rolls involve the risk that the market value of the securities the Fund is obligated to repurchase may decline below the repurchase price, or that the counterparty may default on its obligations. These transactions may also increase the Fund’s portfolio turnover rate. If the Fund reinvests the proceeds of the security sold, the Fund will also be subject to the risk that the investments purchased with such proceeds will decline in value (a form of leverage risk). MBS TBAs and dollar rolls are subject to counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument).

Mortgage- and Other Asset-Backed Securities Risk. The value of any mortgage-backed and other asset-backed securities held by the Fund may be affected by, among other things, changes or perceived changes in: interest rates; factors concerning the interests in and structure of the issuer or the originator of the mortgages or other assets; the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements; or the market's assessment of the quality of underlying assets. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed by the full faith and credit of a particular U.S. Government agency, authority, enterprise or instrumentality, and some, but not all, are also insured or guaranteed by the U.S. Government. Mortgage-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may entail greater risk than obligations guaranteed by the U.S. Government. Mortgage- and other asset-backed securities are subject to prepayment risk, which is the possibility that the underlying mortgage or other asset may be refinanced or prepaid prior to maturity during periods of declining or low interest rates, causing the Fund to have to reinvest the money received in securities that have lower yields. Rising or high interest rates tend to extend the duration of mortgage- and other asset-backed securities, making their prices more volatile and more sensitive to changes in interest rates.

Prepayment and Extension Risk. Prepayment and extension risk is the risk that a bond or other security or investment might, in the case of prepayment risk, be called or otherwise converted, prepaid or redeemed before maturity and, in the case of extension risk, the investment might not be called as expected, and the portfolio managers may not be able to invest the proceeds in other investments providing as high a level of income, resulting in a reduced yield to the Fund. In the case of mortgage- or asset-backed securities, as interest rates decrease or spreads narrow, the likelihood of prepayment increases. Conversely, extension risk is the risk that an unexpected rise in interest rates will extend the life of a mortgage- or asset-backed security beyond the prepayment time. If the Fund’s investments are locked in at a lower interest rate for a longer period of time, the portfolio managers may be unable to capitalize on securities with higher interest rates or wider spreads.

Reinvestment Risk. Reinvestment risk is the risk that the Fund will not be able to reinvest income or principal at the same return it is currently earning.

Depositary Receipts Risk. Depositary receipts are receipts issued by a bank or trust company reflecting ownership of underlying securities issued by foreign companies. Some foreign securities are traded in the form of American Depositary Receipts (ADRs). Depositary receipts involve risks similar to the risks associated with investments in foreign securities, including those associated with the particular country, which may be related to the particular political, regulatory, economic, social and other conditions or events occurring in the country and fluctuations in its currency, as well as market risk tied to the underlying foreign company. In addition, ADR holders may have limited voting rights, may not have the same rights afforded typical company stockholders in the event of a corporate action such as an acquisition, merger or rights offering and may experience difficulty in receiving company stockholder communications.

Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

Derivatives Risk/Futures Contracts Risk. The loss that may be incurred in entering into futures contracts may exceed the amount of the premium paid and may be potentially unlimited. Futures markets are highly volatile and the use of futures may increase the volatility of the Fund’s NAV. Additionally, as a result of the low collateral deposits normally involved in futures trading, a relatively small price movement in a futures contract may result in substantial losses for the Fund. Futures contracts may be illiquid. Furthermore, exchanges may limit fluctuations in futures contract prices during a trading session by imposing a maximum permissible price movement on each futures contract. The Fund may be disadvantaged if it is prohibited from executing a trade outside the daily permissible price movement. Futures contracts executed on foreign exchanges may not provide the same protection as U.S. exchanges. These transactions involve additional risks, including counterparty risk, hedging risk and pricing risk.

Changing Distribution Level Risk. The amount of the distributions paid by the Fund will vary and generally depends on the amount of interest income and/or dividends received by the Fund on the securities it holds. The Fund may not be able to pay distributions or may have to reduce its distribution level if the interest income and/or dividends the Fund receives from its investments decline.

Rule 144A Securities Risk. The Fund may invest significantly in privately placed “Rule 144A” securities that are determined to be liquid in accordance with procedures adopted by the Fund’s Board. However, an insufficient number of qualified institutional buyers interested in purchasing Rule 144A securities at a particular time could affect adversely the marketability of such securities and the Fund might be unable to dispose of such securities promptly or at reasonable prices. Accordingly, even if determined to be liquid, the Fund’s holdings of Rule 144A securities may increase the level of Fund illiquidity if eligible buyers become uninterested in buying them at a particular time. Issuers of Rule 144A securities are required to furnish information to potential investors upon request. However, the required disclosure is much less extensive than that required of public companies and is not publicly available since it is not filed with the SEC. Further, issuers of Rule 144A securities can require recipients of the information (such as the Fund) to agree contractually to keep the information confidential, which could also adversely affect the Fund’s ability to dispose of the security.

Frequent Trading Risk. The portfolio managers may actively and frequently trade investments in the Fund's portfolio to carry out its investment strategies. Frequent trading of investments increases the possibility that the Fund, as relevant, will realize taxable capital gains (including short-term capital gains, which are generally taxable to shareholders at higher rates than long-term capital gains for U.S. federal income tax purposes), which could reduce the Fund's after-tax return. Frequent trading can also mean higher brokerage and other transaction costs, which could reduce the Fund's return. The trading costs and tax effects associated with portfolio turnover may adversely affect the Fund’s performance.

Index Risk. The Fund's value will generally decline when the performance of its targeted index declines. In addition, because the Fund may not hold all issues included in its index, it may not always be fully invested. The Fund also bears advisory, administrative and other expenses and transaction costs in trading securities, which the index does not bear. Accordingly, the Fund's performance will likely fail to match the performance of its targeted index, after taking expenses into account. It is not possible to invest directly in an index.

Highly Leveraged Transactions Risk. The loans or other securities in which the Fund invests may include highly leveraged transactions whereby the borrower assumes large amounts of debt in order to have the financial resources to attempt to achieve its business objectives. Loans or securities that are part of highly leveraged transactions involve a greater risk (including default and bankruptcy) than other investments.

12	Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

Issuer Risk. An issuer in which the Fund invests or to which it has exposure may perform poorly, and the value of its securities may therefore decline, which would negatively affect the Fund’s performance. Poor performance may be caused by poor management decisions, competitive pressures, breakthroughs in technology, reliance on suppliers, labor problems or shortages, corporate restructurings, fraudulent disclosures, natural disasters or other events, conditions or factors.

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. The bar chart shows how the Fund’s Class Z share performance has varied for each full calendar year shown. The table below the bar chart compares the Fund’s returns for the periods shown 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.

Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

Year by Year Total Return (%) as of December 31 Each Year*	Best and Worst Quarterly Returns During the Period Shown in the Bar Chart
	_Best	_{2nd Quarter 2009}	_19.33%
	_Worst	_{4th Quarter 2008}	_-19.26%

*	Year to Date return as of March 31, 2015: 1.50%

Average Annual Total Returns After Applicable Sales Charges (for periods ended December 31, 2014)

	Share Class Inception Date	1 Year	5 Years	10 Years
Class Z	09/25/2002
returns before taxes		5.57%	10.09%	6.55%
returns after taxes on distributions		4.15%	8.98%	5.13%
returns after taxes on distributions and sale of Fund shares		3.34%	7.70%	4.83%
Class A returns before taxes	03/03/2003	-0.75%	8.54%	5.66%
Class B returns before taxes	03/03/2003	-0.17%	9.00%	5.73%
Class C returns before taxes	03/03/2003	3.50%	9.00%	5.49%
Class R4 returns before taxes	11/08/2012	5.61%	10.09%	6.55%
Class R5 returns before taxes	11/08/2012	5.62%	10.11%	6.56%
Class Y returns before taxes	11/08/2012	5.68%	10.14%	6.57%
S&P 500^® Index (reflects no deductions for fees, expenses or taxes)		13.69%	15.45%	7.67%
Barclays U.S. Aggregate Bond Index (reflects no deductions for fees, expenses or taxes)		5.97%	4.45%	4.71%
Lipper Flexible Portfolio Funds Index (reflects no deductions for taxes)		4.31%	8.80%	6.11%
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)		9.85%	10.09%	6.48%

Fund Management

Investment Manager: Columbia Wanger Asset Management, LLC

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Charles P. McQuaid, CFA	Portfolio Manager and Analyst	Lead manager or co-manager since inception in 2002	2002
Christopher J. Olson, CFA	Portfolio Manager and Analyst	Co-manager since 2014	2002

14	Prospectus 2015

Columbia Thermostat Fund^SM

Summary of the Fund (continued)

Purchase and Sale of Fund Shares

You may purchase or redeem shares of the Fund on any business day by contacting the Fund in the ways described below:

Online		Regular Mail		Express Mail		By Telephone
columbiathreadneedle.com/us		Columbia Funds, c/o Columbia Management Investment Services Corp. P.O. Box 8081 Boston, MA 02266-8081		Columbia Funds, c/o Columbia Management Investment Services Corp. 30 Dan Road, Suite 8081 Canton, MA 02021-2809		800.422.3737

The minimum initial investment amounts for the share classes offered by the Fund are shown below:

Minimum Initial Investment

Class	Category of eligible account	For accounts other than systematic investment plan accounts	For systematic investment plan accounts
Classes A, B* & C	All accounts other than IRAs	$2,000	$100
Classes A, B* & C	IRAs	$1,000	$100
Class R4 & Y	All eligible accounts	None	N/A
Class R5	Combined underlying accounts of eligible registered investment advisers	$100,000	N/A
Class R5	Omnibus retirement plans	None	N/A
Class Z	All eligible accounts	$0, $1,000 or $2,000 depending upon the category of eligible investor	$100

*	Class B shares are generally closed to new and existing shareholders.

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 investing through a tax-advantaged account, such as a 401(k) plan or an IRA. The use of a fund-of-funds structure could affect the timing, amount and character of distributions to you and therefore may increase the amount of taxes payable by you. 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

Prospectus 2015

Portfolio Funds Summary

The following 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 columbiathreadneedle.com/us or contact your financial advisor for details.

Columbia Acorn^® Fund

■	The fund seeks long-term capital appreciation.
■	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 initial investment.
■	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).

Columbia Acorn International^®

■	The fund seeks long-term capital appreciation.
■	Under normal circumstances, the fund invests at least 75% of its net 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 initial investment.

Columbia Acorn Select^SM

■	The fund seeks long-term capital appreciation.
■	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 initial investment.
■	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 invests in a limited number of companies (generally between 30-60), offering the potential to provide above-average growth over time.

Columbia Contrarian Core Fund

■	The fund seeks total return, consisting of long-term capital appreciation and current income.
■	Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) 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.
■	The fund may invest up to 20% of its net assets in foreign securities.

Columbia Dividend Income Fund

■	The fund seeks total return, consisting of current income and capital appreciation.
■	Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) 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.
■	The fund may invest in companies that have market capitalizations of any size.
■	The fund may invest up to 20% of its net assets in debt securities, including securities that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high yield securities” or “junk bonds”).

Portfolio Funds Summary (continued)

■	The fund 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 Large Cap Enhanced Core Fund

■	The fund seeks total return before fees and expenses that exceeds the total return of the S&P 500^® Index.
■	Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks that comprise the S&P 500^® Index, convertible securities that are convertible into stocks included in the S&P 500^® Index, and derivatives whose returns are closely equivalent to the returns of the S&P 500^® Index or its components.
■	The fund 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, but it 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 the S&P 500^® Index over time.

■	The fund may from time to time emphasize one or more economic sectors in selecting its investments, including the information technology sector.

■	The fund’s investment manager uses quantitative analysis to evaluate the relative attractiveness of potential investments.
■	The fund may invest in derivatives, such as futures contracts, for investment purposes, for risk management (hedging) purposes and to increase investment flexibility.

Columbia Select Large Cap Growth Fund

■	The fund seeks long-term capital appreciation.

■

Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) in common stocks of U.S. and foreign companies that have market capitalizations, at the time of purchase, in the range of companies in the Russell 1000 Growth Index (between $1.63 billion and $560 billion as of June 30, 2014).

■	The fund invests primarily in common stocks of companies believed to have the potential for long-term growth.

■	The fund typically employs a focused portfolio investing style, which results in fewer holdings than a fund that seeks to achieve its investment objective by investing in a greater number of issuers.

■	The fund may invest directly in foreign securities or indirectly through depositary receipts.

■	The fund may from time to time emphasize one or more economic sectors in selecting its investments, including the consumer discretionary, health care and the information technology and technology-related sectors.

Columbia Income Opportunities Fund

■	The fund seeks to provide shareholders with a high total return through current income and capital appreciation.
■	Under normal market conditions, the fund’s assets are invested primarily in income-producing debt securities, with an emphasis on the higher rated segment of the high-yield (“junk bond”) market.
■	The fund will purchase only securities rated B or above, or if unrated, securities determined to be of comparable quality.
■	The fund may invest up to 25% of its net assets in foreign investments.

■	The fund may from time to time emphasize one or more economic sectors in selecting its investments.

■	The fund may invest in fixed income securities of any maturity and does not seek to maintain a particular dollar-weighted average maturity.

Portfolio Funds Summary (continued)

■	The fund may invest significantly in Rule 144A securities that are determined to be liquid in accordance with procedures adopted by the fund’s Board of Trustees.

Columbia Intermediate Bond Fund

■	The fund seeks total return, consisting of current income and capital appreciation.
■	Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) 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.
■	The fund 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 to be of comparable quality.
■	The fund may invest up to 20% of its net assets in securities that, at the time of purchase, are rated below investment grade or are unrated but determined to be of comparable quality (commonly referred to as “high yield securities” or “junk bonds”).
■	Under normal circumstances, the fund’s dollar-weighted average maturity will be between three and ten years.

■

The fund may invest in derivatives, such as futures (including interest rate futures) and swap contracts (including credit default swaps, credit default swap indexes and interest rate swaps) for hedging purposes and to manage yield curve, duration and interest rate exposure; options (including options on listed futures contracts), collateralized debt obligations and inverse floaters for investment purposes; and interest-only (IO) and principal-only (PO) securities for hedging and investment purposes.

■

The Fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.

■	The fund may invest in private placements.

■	The fund’s investment strategy may involve the frequent trading of portfolio securities. This may cause the fund to incur higher transaction costs (which may adversely affect the fund’s performance) and may increase taxable distributions for shareholders.

Columbia Short Term Bond Fund

■	The fund seeks current income, consistent with minimal fluctuation of principal.
■	Under normal circumstances, the fund invests at least 80% of its net assets (including the amount of any borrowings for investment purposes) 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.
■	The fund invests at least 65% of its total assets in securities that, at the time of purchase, are rated investment grade or are unrated but determined to be of comparable quality.

■	The fund may invest in mortgage- and other asset-backed securities.

■	The fund may invest in floating rate debt securities, which have interest rates that adjust or “float” periodically.

■	The fund may invest in derivatives, including treasury futures, for both hedging and non-hedging purposes including, for example, to seek to enhance returns or as a substitute for a position in an underlying asset, as well as to manage duration, yield curve and/or interest rate exposure.

■	The fund may invest in private placements.

■	The fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.

Portfolio Funds Summary (continued)

■	Under normal circumstances, the fund’s dollar-weighted average effective maturity will be three years or less, and its duration will be three years or less.

Columbia U.S. Government Mortgage Fund

■	The fund seeks to provide shareholders with current income as its primary objective and, as its secondary objective, preservation of capital.
■	The fund’s assets primarily are invested in mortgage-related securities. Under normal market conditions, at least 80% of the fund’s net assets (including the amount of any borrowings for investment purposes) are invested in mortgage-related securities that either are issued or guaranteed as to principal and interest by the U.S. Government, its agencies, authorities or instrumentalities.

■	The fund may invest in stripped mortgage-backed securities such as interest-only (IO) and principal-only (PO) securities.

■	The fund may invest in fixed income securities of any maturity and does not seek to maintain a particular dollar-weighted average maturity.
■	The fund may invest significantly in Rule 144A securities.

■	The fund may invest in derivatives, including forward contracts.
■	The fund may purchase or sell securities on a when-issued, delayed delivery or forward commitment basis. Such securities may include mortgage-backed securities acquired or sold in the “to be announced” (TBA) market and those in a dollar roll transaction.

■	The fund’s investment strategy may involve the frequent trading of portfolio securities. This may cause the fund to incur higher transaction costs (which may adversely affect the fund’s performance) and may increase taxable distributions for shareholders.

Columbia Thermostat Fund^SM

More Information About the Fund

Investment Objective

Columbia Thermostat Fund^SM (the Fund) seeks long-term capital appreciation. The Fund’s investment objective is not a fundamental policy of the Fund and may be changed by the Fund’s Board of Trustees (the Board) without shareholder approval. There is no assurance the Fund’s objective will be achieved.

Principal Investment Strategies

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 Fund’s current allocation table is set forth below.

20	Prospectus 2015

Columbia Thermostat Fund^SM

More Information About the Fund (continued)

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 2225	10%	90%
over 2150 – 2225	15%	85%
over 2075 – 2150	20%	80%
over 2000 – 2075	25%	75%
over 1925 – 2000	30%	70%
over 1850 – 1925	35%	65%
over 1775 – 1850	40%	60%
over 1700 – 1775	45%	55%
over 1625 – 1700	50%	50%
over 1550 – 1625	55%	45%
over 1475 – 1550	60%	40%
over 1400 – 1475	65%	35%
over 1325 – 1400	70%	30%
over 1250 – 1325	75%	25%
over 1175 – 1250	80%	20%
over 1100 – 1175	85%	15%
1100 and under	90%	10%

When the S&P 500^® Index moves into a new band on the table, the Fund 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. Any such rebalancing typically will be implemented promptly. However, there are two circumstances when a rebalancing may be implemented over a longer timeline. First, when a rebalancing or allocation table change would trigger a 10% point or greater change in stock and bond allocations or individual Portfolio Funds, the rebalancing may be implemented over a period of up to two weeks, if deemed by the Investment Manager to be in the best interest of shareholders. The second exception is 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 1680	50% stocks, 50% bonds
Dec. 1	The S&P 500^® goes to 1701	rebalance 45% stocks, 55% bonds
Dec. 6	The S&P 500^® drops back to 1690	no reversal for 31 days

Prospectus 2015

Columbia Thermostat Fund^SM

More Information About the Fund (continued)

Date	Level of the S&P 500^® Index	How the Fund will invest the Stock/ Bond Assets
Jan. 2	The S&P 500^® is at 1650	rebalance 50% stocks, 50% bonds
Jan. 20	The S&P 500^® drops to 1620	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 1630	no reversal for 31 days
Feb. 20	The S&P 500^® is at 1640	rebalance 50% stocks, 50% bonds

Allocation of Stock/Bond Asset Within Asset Classes
	Type of Fund	Allocation
Stock Funds
Columbia Acorn^® Fund	Small/Mid-cap growth	10%
Columbia Acorn International^®	Small/Mid-cap international growth	20%
Columbia Acorn Select^SM	Mid-cap growth	10%
Columbia Contrarian Core Fund	Large-cap blend	20%
Columbia Dividend Income Fund	Large-cap value	20%
Columbia Large Cap Enhanced Core Fund	Large-cap blend	10%
Columbia Select Large Cap Growth Fund	Large-cap growth	10%
Total		100%

Bond Funds	Type of Fund	Allocation
Columbia Income Opportunities Fund	High-yield bond	20%
Columbia Intermediate Bond Fund	Intermediate-term bond	20%
Columbia Short Term Bond Fund	Short term bond	40%
Columbia U.S. Government Mortgage Fund	Government bond	20%
Total		100%

See the Portfolio Funds Summary section of this prospectus for information about the Portfolio Funds’ investment objectives and principal investment strategies.

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.

22	Prospectus 2015

Columbia Thermostat Fund^SM

More Information About the Fund (continued)

■	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

Fund-of-Funds Risk. Determinations regarding asset classes or underlying funds and the Fund’s allocations thereto may not successfully achieve the Fund’s investment objective, in whole or in part. The selected underlying funds’ performance may be lower than the performance of the asset class they were selected to represent or may be lower than the performance of alternative underlying funds that could have been selected to represent the asset class. The Fund also is exposed to the same risks as the underlying funds in direct proportion to the allocation of its assets among the underlying funds. By investing in a combination of underlying funds, the Fund has exposure to the risks of many areas of the market. The ability of the Fund to realize its investment objective will depend, in large part, on the extent to which the underlying funds realize their investment objectives. There is no guarantee that the underlying funds will achieve their respective investment objectives. The performance of underlying funds could be adversely affected if other entities that invest in the same underlying funds make relatively large investments or redemptions in such underlying funds. The Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of each underlying fund are shared by its investors, redemptions by other investors in an underlying fund could result in decreased economies of scale and increased operating expenses for such fund. These transactions might also result in higher brokerage, tax or other costs for an underlying fund. This risk may be particularly important when one investor owns a substantial portion of an underlying fund. The Investment Manager may have potential conflicts of interest in selecting affiliated funds over unaffiliated funds for investment by the Fund, and may also face potential conflicts of interest in selecting affiliated funds, because the fees the Investment Manager receives from some underlying funds may be higher than the fees paid by other underlying funds. Further, because of the Investment Manager’s confidence in its own strategies, investment philosophy and capacities, it will, in selecting underlying funds, at times prefer a fund in the Columbia Acorn Family of Funds over alternative investments. There can be no assurance, however, that a fund in the Columbia Acorn Family of Funds selected for inclusion in Columbia Thermostat Fund’s portfolio will, in fact, outperform similar funds managed by the Investment Manager’s affiliates.

Prospectus 2015

Columbia Thermostat Fund^SM

More Information About the Fund (continued)

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 or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in the Fund. Accordingly, an investment in the Fund could lose money over short or long periods. The market values of the securities the Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Credit Risk. The value of fixed-income securities, or other instruments or assets, may decline if the issuer thereof defaults or otherwise becomes unable or unwilling, or is perceived to be unable or unwilling, to honor its financial obligations, such as making payments to the Fund when due. Various factors could affect the actual or perceived willingness or ability of the issuer to make timely interest or principal payments, including changes in the financial condition of the issuer or in general economic conditions. Fixed-income 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 fixed-income 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. Rating agencies assign credit ratings to certain fixed-income securities to indicate their credit risk. Lower quality or unrated securities held by the Fund may present increased credit risk as compared to higher-rated securities. Non-investment grade fixed-income securities (commonly called “high-yield” or “junk”) are subject to greater price fluctuations and are more likely to experience a default than investment grade securities and therefore may expose the Fund to increased credit risk. If the Fund purchases unrated fixed-income securities, or if the ratings of securities held by the Fund are lowered after purchase, the Fund will depend on analysis of credit risk more heavily than usual.

High-Yield Securities Risk. Securities rated below investment grade (commonly called “high-yield” or “junk” bonds) and unrated securities of comparable quality tend to be more sensitive to credit risk than higher-rated securities and may experience greater price fluctuations in response to perceived changes in the ability of the issuing entity or obligor to pay interest and principal when due than to changes in interest rates. These investments are generally more likely to experience a default than higher-rated securities. High-yield securities are considered to be predominantly speculative with respect to the issuer’s capacity to pay interest and repay principal. These securities typically pay a premium — a higher interest rate or yield — because of the increased risk of loss, including default. High-yield securities may require a greater degree of judgment to establish a price, may be difficult to sell at the time and price the Fund desires, may carry high transaction costs, and also are generally less liquid than higher-rated securities. The securities ratings provided by third party rating agencies are based on analyses by these ratings

24	Prospectus 2015

Columbia Thermostat Fund^SM

More Information About the Fund (continued)

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. In adverse economic and other circumstances, issuers of lower-rated securities are more likely to have difficulty making principal and interest payments than issuers of higher-rated securities.

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 perceived value assessment of that security, or may decline in price, even though the Investment Manager believes the securities are already undervalued. There is also a risk that it may take longer than expected for the value of these investments to rise to the portfolio manager’s perceived 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.

Foreign Securities Risk. Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. The performance of the Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar. Foreign securities may also be less liquid than securities of U.S. companies so that the Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on the Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent the Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

Prospectus 2015

Columbia Thermostat Fund^SM

More Information About the Fund (continued)

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.

Emerging Market Securities Risk. Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with other countries.

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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 China and Russia.

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 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

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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.

Derivatives Risk. Derivatives are financial instruments whose value depends on, or is derived from, the value of other underlying assets. Losses involving derivative instruments may be substantial, because a relatively small movement in the price of an underlying security, instrument, commodity, currency or index may result in a substantial loss for the Fund. In addition to the potential for increased losses, the use of derivative instruments may lead to increased volatility for the Fund. Derivative investments will typically increase the Fund’s exposure to principal risks to which it is otherwise exposed, and may expose the Fund to additional risks. Depending on the type and purpose of the Fund’s derivative investments, these risks may include: correlation risk (there may be an imperfect correlation between the hedge and the opposite position, which is related to hedging risk), counterparty risk (the counterparty to the instrument may not perform or be able to perform in accordance with the terms of the instrument), leverage risk (losses from the derivative instrument may be greater than the amount invested in the derivative instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), and/or liquidity risk (it may not be possible for the Fund to liquidate the instrument at an advantageous time or price), each of which may result in significant losses for the Fund.

Convertible Securities Risk. Convertible securities are subject to the usual risks associated with debt securities, such as interest rate risk (the risk of losses attributable to changes in interest rates) and credit risk (the risk that the issuer of a debt security will default or otherwise become unable, or be perceived to be unable or unwilling, to honor a financial obligation, such as making payments to the Fund when due). Convertible securities also react to changes in the value of the common stock into which they convert, and are thus subject to market risk (the risk that the market values of securities or other investments that the Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise). 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. The Fund may be forced to convert a convertible security before it otherwise would choose to do so, which may decrease the Fund's return.

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receivables such as credit, automobile, student and home equity loans. Mortgage- and other asset-backed securities can have a fixed or an adjustable rate. Mortgage- and other asset-backed securities are subject to prepayment risk, which is the possibility that the underlying mortgage or other asset may be refinanced or prepaid prior to maturity during periods of declining or low interest rates, causing the Fund to have to reinvest the money received in securities that have lower yields. In addition, the impact of prepayments on the value of mortgage- and other asset-backed securities may be difficult to predict and may result in greater volatility. Rising or high interest rates tend to extend the duration of mortgage- and other asset-backed securities, making them more volatile and more sensitive to changes in interest rates. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed (i) by the full faith and credit of the U.S. Government (in the case of securities guaranteed by the Government National Mortgage Association) or (ii) by its agencies, authorities, enterprises or instrumentalities (in the case of securities guaranteed by the Federal National Mortgage Association (FNMA) or the Federal Home Loan Mortgage Corporation (FHLMC)), which are not insured or guaranteed by the U.S. Government (although FNMA and FHLMC may be able to access capital from the U.S. Treasury to meet their obligations under such securities). Mortgage-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may be supported by various credit enhancements, such as pool insurance, guarantees issued by governmental entities, letters of credit from a bank or senior/subordinated structures, and may entail greater risk than obligations guaranteed by the U.S. Government, whether or not such obligations are guaranteed by the private issuer.

Stripped Securities Risk. Stripped securities are the separate income or principal components of debt securities. These securities are particularly sensitive to changes in interest rates, and therefore subject to greater fluctuations in price than typical interest bearing debt securities. For example, stripped mortgage-backed securities have greater interest rate risk than mortgage-backed securities with like maturities, and stripped treasury securities have greater interest rate risk than traditional government securities with identical credit ratings.

Prepayment and Extension Risk. Prepayment risk is the risk that a bond or other security or investment might be called or otherwise converted, prepaid or redeemed before maturity, and extension risk is the risk that the investment might not be called as expected. In the case of prepayment risk, if the investment is converted, prepaid or redeemed before maturity, particularly during a time of declining interest rates or spreads, the portfolio managers may not be able to invest the proceeds in other investments providing as high a level of income, resulting in a reduced yield to the Fund. Conversely, in the case of extension risk, as interest rates rise or spreads widen, the likelihood of prepayment decreases and the maturity of the investment may extend the life of the investment beyond the prepayment time. If the Fund's investments are locked in at a lower interest rate for a longer period of time, the portfolio managers may be unable to capitalize on securities with higher interest rates or wider spreads.

Reinvestment Risk. Reinvestment risk is the risk that the Fund will not be able to reinvest income or principal at the same return it is currently earning.

Derivatives Risk/Futures Contracts Risk. The use of futures contracts is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. A futures contract is a sales contract between a buyer (holding the “long” position) and a seller (holding the “short” position) for an asset with delivery deferred until a future date. The buyer agrees to pay a fixed price at the agreed future date and the seller agrees to deliver the asset. The seller hopes that the market price on the delivery date is less than the agreed upon price, while the buyer hopes for the contrary. The liquidity of the futures markets depends

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More Information About the Fund (continued)

on participants entering into offsetting transactions rather than making or taking delivery. To the extent participants decide to make or take delivery, liquidity in the futures market could be reduced. In addition, futures exchanges often impose a maximum permissible price movement on each futures contract for each trading session. The Fund may be disadvantaged if it is prohibited from executing a trade outside the daily permissible price movement. Moreover, to the extent the Fund engages in futures contracts on foreign exchanges, such exchanges may not provide the same protection as U.S. exchanges. The loss that the Fund may incur in entering into futures contracts may exceed the amount of the premium paid and may be potentially unlimited. Futures markets are highly volatile and the use of futures may increase the volatility of the Fund’s NAV. Additionally, as a result of the low collateral deposits normally involved in futures trading, a relatively small price movement in a futures contract may result in substantial losses for the Fund. Investments in these instruments involve risks, including counterparty risk (the risk that the counterparty to the instrument may not perform or be able to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains) and pricing risk (the risk that the instrument may be difficult to value), each of which may result in significant losses for the Fund.

Rule 144A Securities Risk. The Fund may invest significantly in privately placed “Rule 144A” securities that are determined to be liquid in accordance with procedures adopted by the Fund’s Board. However, an insufficient number of qualified institutional buyers interested in purchasing Rule 144A securities at a particular time could affect adversely the marketability of such securities and the Fund might be unable to dispose of such securities promptly or at reasonable prices. Accordingly, even if determined to be liquid, the Fund’s holdings of Rule 144A securities may increase the level of Fund illiquidity if eligible buyers become uninterested in buying them at a particular time. The Fund may also have to bear the expense of registering the securities for resale and the risk of substantial delays in effecting the registration. Additionally, the purchase price and subsequent valuation of restricted and illiquid securities normally reflect a discount, which may be significant, from the market price of comparable securities for which a more liquid market exists. Issuers of Rule 144A securities are required to furnish information to potential investors upon request. However, the required disclosure is much less extensive than that required of public companies and is not publicly available since it is not filed with the SEC. Further, issuers of Rule 144A securities can require recipients of the information (such as the Fund) to agree contractually to keep the information confidential, which could also adversely affect the Fund’s ability to dispose of the security.

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Highly Leveraged Transactions Risk. The loans or other securities in which the Fund invests may consist of transactions involving refinancings, recapitalizations, mergers and acquisitions and other financings for general corporate purposes. The Fund’s investments also may include senior obligations of a borrower issued in connection with a restructuring pursuant to Chapter 11 of the U.S. Bankruptcy Code (commonly known as “debtor-in-possession” financings), provided that such senior obligations are determined by the Fund’s portfolio managers to be a suitable investment for the Fund. In such highly leveraged transactions, the borrower assumes large amounts of debt in order to have the financial resources to attempt to achieve its business objectives. Such business objectives may include but are not limited to: management’s taking over control of a company (leveraged buy-out); reorganizing the assets and liabilities of a company (leveraged recapitalization); or acquiring another company. Loans or securities that are part of highly leveraged transactions involve a greater risk (including default and bankruptcy) than other investments.

Additional Investment Strategies and Policies

Changing the Fund’s Investment Objective and Policies

Investment Guidelines

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/or 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. Information on the Fund’s holdings can be found in the Fund’s shareholder reports or by visiting columbiathreadneedle.com/us.

Investing in Affiliated Funds

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resulting in lower expense ratios for the Underlying Funds, because the affiliated products may own substantial portions of the shares of Underlying Funds. However, redemption of Underlying Fund shares by one or more affiliated products could cause the expense ratio of an Underlying Fund to increase, as its fixed costs would be spread over a smaller asset base. Because of large positions of certain affiliated products, the Underlying Funds may experience relatively large inflows and outflows of cash due to affiliated products’ purchases and sales of Underlying Fund shares. Although the Investment Manager or Columbia Management may seek to minimize the impact of these transactions where possible, for example, by structuring them over a reasonable period of time or through other measures, Underlying Funds may experience increased expenses as they buy and sell portfolio securities to manage the cash flow effect related to these transactions. Further, when the Investment Manager or Columbia Management structures transactions over a reasonable period of time in order to manage the potential impact of the buy and sell decisions for the affiliated products, those affiliated products, including funds-of-funds, may pay more or less (for purchase activity), or receive more or less (for redemption activity), for shares of the Underlying Funds than if the transactions were executed in one transaction. In addition, substantial redemptions by affiliated products within a short period of time could require the Underlying Fund to liquidate positions more rapidly than would otherwise be desirable, which may have the effect of reducing or eliminating potential gain or causing it to realize a loss. Substantial redemptions may also adversely affect the ability of the Underlying Fund to implement its investment strategy. The Investment Manager or Columbia Management also has an economic conflict of interest in determining the allocation of affiliated products’ assets among the Underlying Funds, as it earns different fees from the various Underlying Funds.

Investing in Money Market Funds

Lending of Portfolio Securities

The Portfolio Fund may lend portfolio securities to broker-dealers or other financial intermediaries on a fully collateralized basis in order to earn additional income. The Portfolio Fund may lose money from securities lending if, for example, the borrower does not return a loaned security and the proceeds from sale of the collateral are not sufficient to replace the borrowed security. The Portfolio Fund invests collateral in a government money market fund.

Investing Defensively

Portfolio Holdings Disclosure

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Cybersecurity

Use of Benchmarks

FUNDamentals

Portfolio Holdings Versus the Benchmarks

Mailings to Households

Additional Information on Portfolio Turnover

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 transactions. See the Financial Highlights section of this prospectus for the Fund's portfolio turnover rates for the past five years.

Cash Flows

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Understanding Annual Fund Operating Expenses

FUNDamentals

Other Expenses

Fee Waiver/Expense Reimbursement Arrangements and Impact on Past Performance

The Investment Manager has contractually agreed to waive fees and reimburse certain expenses of the Fund so that ordinary operating expenses (excluding transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund's investment in the Portfolio Funds (acquired funds)) do not exceed the annual rates shown below through April 30, 2016. This arrangement may only be modified or amended with approval from all parties to such arrangements, 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.

Columbia Thermostat Fund
Class A	0.50%
Class B	1.00%
Class C	1.25%
Class R4	0.25%
Class R5	0.24%
Class Y	0.19%
Class Z	0.25%

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Effect of Fee Waivers and/or Expense Reimbursements on Past Performance. The Fund’s returns shown in the Performance Information section of this prospectus reflect the effect of any fee waivers and/or reimbursements of Fund expenses by the Investment Manager and/or any of its affiliates and any predecessor firms that were in place during the performance period shown. Without such fee waivers/expense reimbursements, the Fund’s returns might have been lower.

Board of Trustees

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

Primary Service Providers

The Investment Manager

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. A discussion regarding the basis for the Board approving the renewal of the Fund's investment management services agreement with the Investment Manager is available in the Fund’s semiannual report to shareholders for the fiscal period ended June 30, 2014.

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Portfolio Managers

Portfolio Manager	Title	Role with Fund	Service with the Fund Since
Charles P. McQuaid, CFA	Portfolio Manager and Analyst	Lead manager or co-manager since inception in 2002	2002
Christopher J. Olson, CFA	Portfolio Manager and Analyst	Co-manager since 2014	2002

Mr. McQuaid has been associated with the Investment Manager or its predecessors as an investment professional since 1978. He served as a Trustee of the Trust from 1992 until February 2015, as President of the Trust from 2003 through March 2014, and is currently a Vice President of the Trust. From October 2003 through March 2014, Mr. McQuaid served as President and Chief Investment Officer of the Investment Manager or its predecessors. 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

Annual Administration Fee, as a % of Aggregate 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

The Transfer Agent

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shareholder or "sub-transfer agency" services. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which you may hold Fund shares, pursuant to which the Transfer Agent pays these financial intermediaries for providing certain shareholder services. The Fund generally pays the Transfer Agent a per account fee for each open account and compensates the Transfer Agent for certain out-of-pocket expenses. In addition, subject to certain limitations, the Fund compensates the Transfer Agent for payments made 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. The Transfer Agent is contractually obligated to oversee such intermediaries for the purpose of reasonably assuring their compliance with applicable law and the terms of their agreements to provide the shareholder services. 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

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 and the other Columbia Funds and the sale of their shares;

■	there may be competition for limited investment opportunities that must be allocated among the Fund, the other Columbia Funds and 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 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;

■

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

■

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Certain Legal Matters

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Choosing a Share Class

The Funds

Funds Contact Information

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

FUNDamentals

Selling and/or Servicing Agents

Omnibus Accounts

Retirement Plans and Omnibus Retirement Plans

Summary of Share Class Features

■	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.

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Share Class Features

Share Class	Eligible Investors; Minimum Initial Investments	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; $1,000 for IRAs	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 after 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 after purchase	Service Fee: 0.25%
Class B	Eligibility: Closed to new investors^(c) Note: Class B shares convert to Class A shares eight years after purchase^(d) Minimum Initial Investment: N/A	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	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: 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: None	None	None	Distribution Fee: 0.50%

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Share Class	Eligible Investors; Minimum Initial Investments	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: 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	None	None	None
Class Y	Eligibility: Available only to retirement plans that maintain plan-level or omnibus accounts with the Fund^(c) Minimum Initial Investment: None	None	None	None

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Share Class	Eligible Investors; Minimum Initial Investments	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; 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	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)

(c)	These share classes are 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:

(d)	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

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Class A Shares — Front-End Sales Charge

FUNDamentals

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 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
Breakpoint Schedule For:	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
Class A Shares	$ 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)

(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.

■

■	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

Contingent Deferred Sales Charge

Class A Shares — Commissions

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The Distributor may also pay your selling agent a cumulative commission when you buy Class A shares in amounts not subject to initial sales charges, 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

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

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).

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Class B Shares — Conversion to Class A Shares

Class C Shares — Front-End Sales Charge

Class C Shares — CDSC

Class C Shares — Commissions

Class R Shares — Sales Charges and Commissions

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%

Reductions/Waivers of Sales Charges

Front-End Sales Charge Reductions

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FUNDamentals

Your “Immediate Family” and Account Value Aggregation

Eligible Accounts

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Front-End Sales Charge Waivers

CDSC Waivers

Repurchases

Restrictions and Changes in Terms and Conditions

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Choosing a Share Class (continued)

Distribution and Service Fees

	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

Selling Agent Compensation

50	Prospectus 2015

Columbia Thermostat Fund^SM

Choosing a Share Class (continued)

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares

Share Price Determination

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

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

Business Days

52	Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Transaction Rules and Policies

Order Processing

“Good Form”

Medallion Signature Guarantees

Customer Identification Program

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Information Sharing Agreements

Excessive Trading Practices Policy

54	Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

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.

Opening an Account and Placing Orders

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Accounts Established Directly with the Fund

Written Transactions

56	Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Telephone Transactions

Online Transactions

Wire Transactions

Electronic Funds Transfer

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Buying Shares

Eligible Investors

Class A and Class C Shares

Class B Shares (Closed)

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).

Class I Shares

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

Class R Shares

58	Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Class R4 Shares

Class R5 Shares

Class Y Shares

Class Y shares are available only to retirement plans that maintain plan-level or omnibus accounts with the Fund (through the Transfer Agent).

Class Z Shares

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

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.

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

Minimum Initial Investments
	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, Class R4 and Class Y	None	N/A
Class R5	variable ^(b)	N/A
Class Z	variable ^(c)	variable ^(c)

(a)

(b)

(c)

Class Z Shares Minimum Initial Investments

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

■

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

■

60	Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

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

■	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.

■

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

■

■	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.

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

Systematic Investment Plan

Dividend Diversification

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

Your sale price will be the next NAV calculated after your request is received in “good form,” minus any applicable CDSC.

Systematic Withdrawal Plan

62	Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

In-Kind Redemptions

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 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 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 trading thereon is restricted or during emergency or other circumstances, including 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

Systematic Exchanges

Prospectus 2015

Columbia Thermostat Fund^SM

Buying, Selling and Exchanging Shares (continued)

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

■

■	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 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).

64	Prospectus 2015

Columbia Thermostat Fund^SM

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.

■

FUNDamentals

Distributions

Declaration and Distribution Schedule
Declarations	semiannually
Distributions	semiannually

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

66	Prospectus 2015

Columbia Thermostat Fund^SM

Distributions and Taxes (continued)

Taxes

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

■

Prospectus 2015

Columbia Thermostat Fund^SM

Distributions and Taxes (continued)

■

For a Fund organized as a fund-of-funds: Because most of the Fund's investments are shares of underlying 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 Underlying Funds or the Fund shareholders invested directly in the Underlying 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

Taxes

68	Prospectus 2015

Columbia Thermostat Fund^SM

Financial Highlights

Prospectus 2015

Columbia Thermostat Fund^SM

Financial Highlights (continued)

	Net Asset Value, Beginning of Period	Income from Investment Operations		Total from investment operations	Less Distributions to Shareholders
(Selected data for a share outstanding throughout each period)	Net Asset Value, Beginning of Period	Net investment income	Net realized and unrealized gain	Total from investment operations	Net investment income	Net realized gains
Class A
Year Ended December 31, 2014	$14.58	0.28	0.49	0.77	(0.28)	(0.21)
Year Ended December 31, 2013	$14.29	0.29	1.00	1.29	(0.25)	(0.75)
Year Ended December 31, 2012	$12.82	0.32	1.39	1.71	(0.24)	—
Year Ended December 31, 2011	$12.58	0.28	0.30	0.58	(0.34)	—
Year Ended December 31, 2010	$10.90	0.19	1.67	1.86	(0.18)	—
Class B
Year Ended December 31, 2014	$14.68	0.21	0.50	0.71	(0.21)	(0.21)
Year Ended December 31, 2013	$14.39	0.19	1.03	1.22	(0.18)	(0.75)
Year Ended December 31, 2012	$12.91	0.20	1.45	1.65	(0.17)	—
Year Ended December 31, 2011	$12.64	0.15	0.38	0.53	(0.26)	—
Year Ended December 31, 2010	$10.93	0.13	1.67	1.80	(0.09)	—
Class C
Year Ended December 31, 2014	$14.68	0.17	0.49	0.66	(0.17)	(0.21)
Year Ended December 31, 2013	$14.39	0.18	1.00	1.18	(0.14)	(0.75)
Year Ended December 31, 2012	$12.91	0.22	1.39	1.61	(0.13)	—
Year Ended December 31, 2011	$12.62	0.18	0.31	0.49	(0.20)	—
Year Ended December 31, 2010	$10.91	0.10	1.68	1.78	(0.07)	—
Class R4
Year Ended December 31, 2014	$14.46	0.32	0.49	0.81	(0.32)	(0.21)
Year Ended December 31, 2013	$14.19	0.36	0.95	1.31	(0.29)	(0.75)
Year Ended December 31, 2012^(d)	$14.08	0.09	0.28	0.37	(0.26)	—
Class R5
Year Ended December 31, 2014	$14.47	0.31	0.50	0.81	(0.32)	(0.21)
Year Ended December 31, 2013	$14.19	0.37	0.96	1.33	(0.30)	(0.75)
Year Ended December 31, 2012^(f)	$14.08	0.09	0.27	0.36	(0.25)	—
Class Y
Year Ended December 31, 2014	$14.46	0.32	0.50	0.82	(0.33)	(0.21)
Year Ended December 31, 2013	$14.18	0.33	1.01	1.34	(0.31)	(0.75)
Year Ended December 31, 2012^(g)	$14.08	0.09	0.27	0.36	(0.26)	—
Class Z
Year Ended December 31, 2014	$14.40	0.32	0.48	0.80	(0.32)	(0.21)
Year Ended December 31, 2013	$14.13	0.32	0.99	1.31	(0.29)	(0.75)
Year Ended December 31, 2012	$12.67	0.34	1.39	1.73	(0.27)	—
Year Ended December 31, 2011	$12.44	0.31	0.29	0.60	(0.37)	—
Year Ended December 31, 2010	$10.80	0.21	1.66	1.87	(0.23)	—

Notes to Financial Highlights

(a)	Had the Investment Manager and/or its affiliates not waived fees and/or reimbursed a portion of expenses, total return would have been reduced.

(b)	In addition to the fees and expenses that the Fund bears directly, the Fund indirectly bears a pro rata share of the fees and expenses of the underlying funds in which the Fund invests, if any. Such indirect expenses are not included in the Fund’s reported expense ratios.

(c)	The benefits derived from custody fees paid indirectly had an impact of less than 0.01%.

(d)	Class R4 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(e)	Annualized.

(f)	Class R5 shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

(g)	Class Y shares commenced operations on November 8, 2012. Per share data and total return reflect activity from that date.

70	Prospectus 2015

Columbia Thermostat Fund^SM

Financial Highlights (continued)

Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return ^(a)	Ratio to Average Net Assets			Supplemental Data
Total Distributions to Shareholders	Net Asset Value, End of Period	Total Return ^(a)	Total gross expenses ^(b)	Total net expenses ^(b)	Net investment income	Portfolio turnover rate	Net assets, end of period (000s)

(0.49)	$14.86	5.30%	0.51%	0.50%	1.88%	95%	$450,258
(1.00)	$14.58	9.07%	0.52%	0.50%	1.91%	92%	$513,293
(0.24)	$14.29	13.34%	0.58%	0.50% ^(c)	2.28%	109%	$323,750
(0.34)	$12.82	4.62%	0.67%	0.50% ^(c)	2.17%	130%	$79,744
(0.18)	$12.58	17.28%	0.72%	0.50% ^(c)	1.64%	118%	$44,527

(0.42)	$14.97	4.83%	1.15%	1.00%	1.39%	95%	$1,231
(0.93)	$14.68	8.49%	1.15%	1.00%	1.29%	92%	$2,263
(0.17)	$14.39	12.78%	1.16%	1.00% ^(c)	1.47%	109%	$4,480
(0.26)	$12.91	4.19%	1.23%	1.00% ^(c)	1.18%	130%	$11,318
(0.09)	$12.64	16.64%	1.28%	1.00% ^(c)	1.10%	118%	$28,752

(0.38)	$14.96	4.50%	1.26%	1.25%	1.14%	95%	$404,456
(0.89)	$14.68	8.23%	1.27%	1.25%	1.16%	92%	$430,173
(0.13)	$14.39	12.52%	1.32%	1.25% ^(c)	1.56%	109%	$253,641
(0.20)	$12.91	3.87%	1.43%	1.25% ^(c)	1.40%	130%	$33,378
(0.07)	$12.62	16.43%	1.49%	1.25% ^(c)	0.88%	118%	$21,866

(0.53)	$14.74	5.61%	0.26%	0.25%	2.14%	95%	$23,412
(1.04)	$14.46	9.26%	0.28%	0.25%	2.39%	92%	$14,651
(0.26)	$14.19	2.60%	0.42% ^(e)	0.25% ^(c)(e)	4.59% ^(e)	109%	$15

(0.53)	$14.75	5.62%	0.24%	0.23%	2.11%	95%	$3,536
(1.05)	$14.47	9.35%	0.25%	0.23%	2.44%	92%	$979
(0.25)	$14.19	2.58%	0.35% ^(e)	0.27% ^(c)(e)	4.60% ^(e)	109%	$3

(0.54)	$14.74	5.68%	0.19%	0.18%	2.19%	95%	$401
(1.06)	$14.46	9.46%	0.14%	0.14%	2.23%	92%	$3
(0.26)	$14.18	2.55%	0.30% ^(e)	0.22% ^(c)(e)	4.63% ^(e)	109%	$3

(0.53)	$14.67	5.57%	0.25%	0.24%	2.16%	95%	$377,119
(1.04)	$14.40	9.30%	0.26%	0.25%	2.14%	92%	$375,444
(0.27)	$14.13	13.69%	0.30%	0.25% ^(c)	2.48%	109%	$292,732
(0.37)	$12.67	4.85%	0.34%	0.25% ^(c)	2.43%	130%	$65,167
(0.23)	$12.44	17.58%	0.37%	0.25% ^(c)	1.87%	118%	$36,130

Prospectus 2015

Columbia Acorn Family of Funds

Additional Information About the Fund

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: columbiathreadneedle.com/us

Shareholder Communications with the Board

Information Provided by the SEC

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

PRO235_12_E01_(05/15)

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, 2015. The most recent annual report for the Funds, which includes the Funds’ audited financial statements dated December 31, 2014, is incorporated by reference into this SAI.

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 columbiathreadneedle.com/us.

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 columbiathreadneedle.com/us, or by accessing the SEC’s website at 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:

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.

The Trust is an open-end investment company registered 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 the Trust. 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 an open-end 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.

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 (other than 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 February 27, 2015. 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.

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 prospectus.

The overall investment and other activities of the Investment Manager and its affiliates may limit the investment opportunities for each Fund in certain markets, industries or transactions or in individual issuers where limitations are imposed by regulators upon the aggregate amount of investment by the Funds and other accounts managed by the Investment Manager and accounts of its affiliates. 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.

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 prospectus. 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.

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.

For purposes of applying the limitations included in the issuer diversification policies set forth below, the Funds do not consider futures or swaps central counterparties, where the Funds have exposure to such central counterparties in the course of making investments in futures and securities, to be issuers.

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.

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).

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.

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.

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.

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.

10. Issue any senior security except to the extent permitted under the Investment Company Act of 1940.

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).

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.

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.

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.

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:

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).

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.

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.

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.

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).

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.

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 Fund other than Columbia Thermostat Fund, as a matter of non-fundamental policy, may not: if its shares are purchased by another investment company in reliance on Section 12(d)(1)(G) of the 1940 Act, purchase securities of another registered open-end investment company or registered unit investment trust in reliance on Section 12(d)(1)(F) or (G) of the 1940 Act, for so long as the Fund’s shares are held by such other investment company.

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.

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.

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 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.

Columbia Acorn Emerging Markets Fund, as a matter of non-fundamental policy, may not:

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.

For the Portfolio Funds’ investment policies, refer to their respective statements of additional information, which are available on the Columbia Funds website at columbiathreadneedle.com/us and on the SEC’s website at 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.

Each Fund’s prospectus identifies and summarizes 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 prospectus, Columbia Thermostat Fund invests in the following Portfolio Funds: Columbia Acorn Fund, Columbia Acorn Select, Columbia Acorn 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 Short Term Bond 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 prospectus. A Fund generally has the ability to invest 10% or more of its total assets in each type of security described in its prospectus (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 prospectus (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, a Fund 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.

See also About the Funds’ Investments — Permissible Investments and Related Risks — Money Market Instruments.

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 as, among others, motor vehicle installment sales, contracts, installment loan contracts, leases of various types of real and personal property, and

receivables from revolving (credit card) agreements. Such securities entitle the security holders to receive distributions (i.e., principal and interest) that are tied to the payments made by the borrower 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 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 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 Investments — Private Placement and Other Restricted Securities for more information.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with asset-backed securities include: Credit Risk, Interest Rate Risk, Liquidity Risk and Prepayment and Extension Risk. See Information Regarding Risks.

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. 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 banks with interest and principal paid in U.S. dollars. Eurodollar and Yankee Dollar 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. See Permissible Fund Investments — Eurodollar and Yankee Dollar and Related Derivatives Instruments. 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. 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.

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 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 and/or heightened 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 and/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 (including by being less stringent) from those applicable to domestic banks. Foreign banks generally are not subject to examination by any U.S. Government agency or instrumentality. See Permissible Fund Investments — Foreign Securities.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with bank obligations include: Counterparty Risk, Credit Risk, Interest Rate Risk, Issuer Risk, Liquidity Risk and Prepayment and Extension Risk. See Information Regarding Risks.

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. See Permissible Fund Investments — Foreign Securities. Common stock may be privately placed or publicly offered. The price of common stock is generally determined by corporate earnings, type of products or services offered, projected growth rates, experience of management, liquidity, and market conditions generally. In the event that a corporation declares bankruptcy or is liquidated, the claims of secured and unsecured creditors and owners of bonds and preferred stock take precedence over the claims of those who own common stock. See Permissible Fund Investments — Private Placement and Other Restricted Securities — Preferred Stock and Permissible Fund Investments — Convertible 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:

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with common stock include: Issuer Risk and Market Risk. See Information Regarding Risks.

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 common stock market movements can influence their value, convertible securities generally are not as sensitive to changes in interest rates as similar non-convertible debt securities nor generally as sensitive to changes in share price as the 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, Permissible Fund Investments — Common Stock, Permissible Fund Investments — Corporate Debt Securities and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

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 at 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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with convertible securities include: Convertible Securities Risk, Interest Rate Risk, Issuer Risk, Market Risk, Prepayment and Extension Risk and Reinvestment Risk. See Information Regarding Risks.

Corporate debt securities are long and short term fixed income securities typically issued by businesses to finance their operations. Corporate debt securities are issued by public or private companies, as distinct from debt securities issued by a government or its agencies. The issuer of a corporate debt security often has a contractual obligation to pay interest at a stated rate on specific dates and to repay principal periodically or on a specified maturity date. Corporate debt securities typically have four distinguishing features: (i) they are taxable; (ii) they have a par value of $1,000; (iii) they have a term maturity, which means they come due at a specified time period; and (iv) many are traded on major securities exchanges. 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, as are debentures. 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 and step-coupon securities and may be privately placed or publicly

offered. They may also be senior or subordinated obligations. See Appendix A for a discussion of securities ratings. See Permissible Fund Investments — Variable- and Floating-Rate Obligations, Permissible Fund Investments — Zero-Coupon, Pay-in-Kind and Step-Coupon Securities, Permissible Fund Investments — Private Placement and Other Restricted Securities, Permissible Fund Investments — Debt Obligations, Permissible Fund Investments — Commercial Paper and Permissible Fund Investments — High Yield 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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with corporate debt securities include: Credit Risk, Interest Rate Risk, Issuer Risk, High Yield Securities Risk, Prepayment and Extension Risk and Reinvestment Risk. See Information Regarding Risks.

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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with custody receipts and trust certificates include: Liquidity Risk and Counterparty Risk. See Information Regarding Risks. In addition, custody receipts and trust certificates generally are subject to the same risks as the securities evidenced by the receipts or certificates.

Many different types of debt obligations exist (for example, bills, bonds, and notes). Issuers of debt obligations have a contractual obligation to pay interest at a fixed, variable or floating rate on specified dates and to repay principal by a specified maturity date. Certain debt obligations (usually intermediate and long-term bonds) have provisions that allow the issuer to redeem or “call” a bond before its maturity. Issuers are most likely to call these securities during periods of falling interest rates. When this happens, an investor may have to replace these securities with lower yielding securities, which could result in a lower return.

The market value of debt obligations is affected primarily by changes in prevailing interest rates and the issuer’s perceived ability to repay the debt. The market value of a debt obligation generally reacts inversely to interest rate changes. When prevailing interest rates decline, the market value of the bond usually rises, and when prevailing interest rates rise, the market value of the bond usually declines.

In general, the longer the maturity of a debt obligation, the higher its yield and the greater the sensitivity to changes in interest rates. Conversely, the shorter the maturity, the lower the yield and the lower the sensitivity to changes in interest rates.

As noted, the values of debt obligations also may be affected by changes in the credit rating or financial condition of their issuers. Generally, the lower the quality rating of a security, the higher the degree of risk as to the payment of interest and return of principal. To compensate investors for taking on such increased risk, those issuers deemed to be less creditworthy generally must offer their investors higher interest rates than do issuers with better credit ratings. See Permissible Fund Investments — Corporate Debt Securities and High Yield Securities.

Determining Investment Grade for Purposes of Investment Policies. When determining whether a security is investment grade or below investment grade for purposes of investment policies regarding investments in such securities, the Funds, including the Portfolio Funds, generally will apply one of the following methodologies, as identified within its shareholder reports, when available. These methodologies typically make use of credit quality ratings assigned by a third-party rating agency or agencies, when available. Credit quality ratings assigned by a rating agency are subjective opinions, not statements of fact, and are subject to change, including daily. Credit quality ratings apply to a Fund’s or Portfolio Fund’s debt instrument investments and not the Fund or Portfolio Fund itself. In general, bond ratings apply to the underlying holdings of the Fund and not the Fund itself.

Ratings limitations under a Fund’s or a Portfolio Fund’s investment policies are applied at the time of purchase by a Fund or Portfolio Fund. Subsequent to purchase, a debt instrument may cease to be rated by a rating agency or its rating may be reduced by one more rating agencies below the minimum required for purchase by a Fund. Neither event will require the sale of such debt instrument, but it may be a factor in considering whether to continue to hold the instrument. Unless otherwise stated in a Fund’s or a Portfolio Fund’s prospectus or in this SAI, a Fund or a Portfolio Fund may invest in debt instruments that are not rated by a rating agency. When a debt instrument is not rated by a rating agency, the Investment Manager or, as applicable, the investment adviser to a Portfolio Fund or a Portfolio Fund subadviser determines, at the time of purchase, whether such debt instrument is of investment grade or below investment grade (e.g., junk bond) quality. A Fund’s or Portfolio Fund’s debt instrument holdings that are not rated by a rating agency are typically referred to as “Not Rated” within the Fund’s shareholder reports.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with debt obligations include: Confidential Information Access Risk, Credit Risk, Highly Leveraged Transactions Risk, Impairment of Collateral Risk, Interest Rate Risk, Issuer Risk, Liquidity Risk, Prepayment and Extension Risk and Reinvestment Risk. See Information Regarding Risks.

Determining Average Maturity. When determining the average maturity of a Fund’s or a Portfolio Fund’s portfolio, the Investment Manager or the Portfolio Fund’s investment adviser may use the effective maturity of a portfolio security by, among other things, adjusting for interest rate reset dates, call dates or “put” dates.

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), 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. Many derivative instruments often require little or no initial payment and may therefore often create inherent economic leverage. Derivatives, when used properly, provide an opportunity for enhanced returns and may be useful in hedging portfolios and managing risk. 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; collateralized mortgage obligations (CMOs); stripped securities; warrants and rights; swap agreements and swaptions.

A Fund may use derivatives for a variety of reasons, including, for example in an attempt: (i) to enhance its return; (ii) protect against possible unfavorable 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; (vi) to manage the effective maturity or duration of its portfolio; and/or (vii) to increase available cash while remaining fully invested.

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. The use of derivatives is a function of numerous variables, including market conditions. See also Permissible Fund Investments — Warrants and Rights and Permissible Fund Investments — When Issued, Delayed Delivery and Forward Commitment Transactions.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with transactions in derivatives (including the derivatives instruments discussed below) include: Counterparty Risk, Credit Risk, Interest Rate Risk, Leverage Risk, Liquidity Risk, Market Risk, Derivatives Risk, Derivatives Risk/Credit Default Swaps Risk, Derivatives Risk/Forward Foreign Currency Contracts Risk, Derivatives Risk/Forward Interest Rate Agreements Risk, Derivatives Risk/Futures Contracts Risk, Derivatives Risk/Interest Rate Swaps Risk, Derivatives Risk/Inverse Floaters Risk, Derivatives Risk/Options Risk, Derivatives Risk/Portfolio Swaps and Total Return Swaps Risk, Derivatives Risk/Total Return Swaps Risk, and Derivatives Risk/Warrants Risk. See Information Regarding Risks.

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, 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 or interest rates. For example, a Fund may invest in debt 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. A trust funds the purchase of a bond by issuing two classes of certificates: short-term floating rate notes (typically sold to third parties) and the inverse floaters (also known as residual certificates). No additional income beyond that provided by the trust’s underlying bond is created; rather, that income is merely divided-up between the two classes of certificates. Generally, income on inverse floating rate bonds will decrease when interest rates increase, and will increase when interest rates decrease. Such securities can have the effect of providing a degree of investment leverage, since they may increase or decrease in value in response to changes in market interest rates at a rate that is a multiple of the actual 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. 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 securities are indirectly subject to the risks associated with derivative instruments. 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.

Index-, Commodity- and Currency-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. 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- and currency-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 may not perform as expected by the Investment Manager. Markets and

underlying investments 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, although the SEC has issued exemptive relief permitting investment companies such as the Funds to invest beyond the limits of Section 12(d)(1)(A) subject to certain conditions. SPDRs generally 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 levels of fees with respect to investments in such unit investment trusts.

Because linked securities 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 linked securities 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. Structured products may be less liquid than other debt securities (or illiquid), and the price of structured products may be more volatile. A Fund’s use of structured products may not work as intended. If structured products are used to reduce the duration of a Fund’s portfolio, this may limit a Fund’s return when having a longer duration would be beneficial (for instance, when interest rates decline).

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.

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 CEA by the CFTC a U.S. Government agency. See Permissible Fund Investments — Derivatives — CFTC Regulation below for information on CFTC regulation.

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.

Upon entering into futures contracts, in compliance with regulatory 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 designated on the Fund’s books and records.

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 or designated 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 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 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).

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, but not the obligation, 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 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 regulatory requirements, it has designated cash or liquid securities at least equal in value to the underlying security’s or other asset’s value (less any applicable margin deposits). 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.

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.

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 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.

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. 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.

Writing Covered Options. A Fund may write covered call options and covered put options on securities held in its portfolio. 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 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 liquid assets 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.

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, including 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. OTC options (options not traded on exchanges) are generally established through negotiation with the other party to the options contract. 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 prospectus) 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.

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, commodity, commodity futures, equity, equity index, credit default, bond futures, total return, portfolio 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.

Swap agreements are usually entered into without an upfront payment because the value of each party’s position is the same. The market values of the underlying commitments will change over time, resulting in one of the commitments being worth more than the other and the net market value creating a risk exposure for one party or the other.

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. A total return swap agreement provides exposure to the non-floating rate side 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. In interest rate collar transactions, one party sells a cap and purchases a floor, or vice versa, in an attempt to protect itself against interest rate movements exceeding given minimum or maximum levels or collar amounts.

Some swap agreements can be used 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. In that case, 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.

Because swaps are two-party contracts that may be subject to contractual restrictions on transferability and termination and because they may have terms of greater than seven days, swap agreements may be considered to be illiquid. If a swap is not liquid, it may not be possible to initiate a transaction or liquidate a position at an advantageous time or price, which may result in significant losses.

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. When a counterparty’s obligations are not fully secured by collateral, then the Fund is essentially an unsecured creditor of the counterparty. If the counterparty defaults, the Fund will have contractual remedies, but there is no assurance that a counterparty will be able to meet its obligations pursuant to such contracts or that, in the event of default, the Fund will succeed in enforcing contractual remedies. Counterparty risk still exists even if a counterparty’s obligations are secured by collateral because the Fund’s interest in collateral may not be perfected or additional collateral may not be promptly posted as required. Counterparty risk also may be more pronounced if a counterparty’s obligations exceed the amount of collateral held by the Fund (if any), the Fund is unable to exercise its interest in collateral upon default by the counterparty, or the termination value of the instrument varies significantly from the marked-to-market value of the instrument.

Counterparty risk with respect to derivatives will be affected by new rules and regulations affecting the derivatives market. Some derivatives transactions are required to be centrally cleared, and a party to a cleared derivatives transaction is subject to the credit risk of the clearing house and the clearing member through which it holds its cleared position, rather than the credit risk of its original counterparty to the derivative transaction. Credit risk of market participants with respect to derivatives that are centrally cleared is concentrated in a few clearing houses, and it is not clear how an insolvency proceeding of a clearing house would be conducted and what impact an insolvency of a clearing house would have on the financial system. A clearing member is obligated by contract and by applicable regulation to segregate all funds received from customers with respect to cleared derivatives transactions from the clearing member’s proprietary assets. However, all funds and other property received by a clearing broker from its customers are generally held by the clearing broker on a commingled basis in an omnibus account, and the clearing member may invest those funds in certain instruments permitted under the applicable regulations. The assets of a Fund might not be fully protected in the event of the bankruptcy of a Fund’s clearing member, because the Fund would be limited to recovering only a pro rata share of all available funds segregated on behalf of the clearing broker’s customers for a relevant account class. Also, the clearing member is required to transfer to the clearing organization the amount of margin required by the clearing organization for cleared derivatives, which amounts are generally held in an omnibus account at the clearing organization for all customers of the clearing member. Regulations promulgated by the CFTC require that the clearing member notify the clearing house of the amount of initial margin provided by the clearing member to the clearing organization that is attributable to each customer. However, if the clearing member does not provide accurate reporting, the Funds are subject to the risk that a clearing organization will use a Fund’s assets held in an omnibus account at the clearing organization to satisfy payment obligations of a defaulting customer of the clearing member to the clearing organization. In addition, clearing members generally provide to the clearing organization the net amount of variation margin required for cleared swaps for all of its customers in

the aggregate, rather than the gross amount of each customer. The Funds are therefore subject to the risk that a clearing organization will not make variation margin payments owed to a Fund if another customer of the clearing member has suffered a loss and is in default, and the risk that a Fund will be required to provide additional variation margin to the clearing house before the clearing house will move the Fund’s cleared derivatives transactions to another clearing member. In addition, if a clearing member does not comply with the applicable regulations or its agreement with the Funds, or in the event of fraud or misappropriation of customer assets by a clearing member, a Fund could have only an unsecured creditor claim in an insolvency of the clearing member with respect to the margin held by the clearing member. See also Permissible Fund Investments —Additional Risk Factors in Cleared Derivatives Transactions.

Interest Rate Swaps. Interest rate swap agreements are often used to obtain or preserve a desired return or spread at a lower cost than through a direct investment in an instrument that yields the desired return or spread. They are financial instruments that involve the exchange of one type of interest rate cash flow for another type of interest rate cash flow on specified dates in the future. In a standard interest rate swap transaction, two parties agree to exchange their respective commitments to pay fixed or floating interest rates on a predetermined specified (notional) amount. The swap agreement’s notional amount is the predetermined basis for calculating the obligations that the swap counterparties have agreed to exchange. Under most swap agreements, the obligations of the parties are exchanged on a net basis. The two payment streams are netted out, with each party receiving or paying, as the case may be, only the net amount of the two payments. Interest rate swaps can be based on various measures of interest rates, including LIBOR, swap rates, Treasury rates and foreign interest rates.

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 a credit default swap. 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 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.

A Fund’s obligations under a credit default swap agreement will be accrued daily (offset against any amounts owing to the Fund). In connection with credit default swaps in which a Fund is the buyer, the Fund will segregate or designate cash or other liquid assets, or enter into certain offsetting positions, with a value at least equal to the Fund’s exposure (any accrued but unpaid net amounts owed by the Fund to any counterparty), on a mark-to-market basis. In connection with credit default swaps in which a Fund is the seller, the Fund will segregate or designate cash or other liquid assets, or enter into offsetting positions, with a value at least equal to

the full notional amount of the swap (minus any amounts owed to the Fund). Such segregation or designation is intended to ensure that a Fund has assets available to satisfy its obligations with respect to the transaction. Such segregation or designation will not limit a Fund’s exposure to loss.

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.

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 at least equal to the accrued excess will be designated 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 designated 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.

Commodity-Linked Swaps. Commodity-linked swaps are two-party contracts in which the parties agree to exchange the return or interest rate on one instrument for the return of a particular commodity, commodity index or commodities futures or options contract. The payment streams are calculated by reference to an agreed upon notional amount. A one-period swap contract operates in a manner similar to a forward or futures contract because there is an agreement to swap a commodity for cash at only one forward date. A Fund may engage in swap transactions that have more than one period and therefore more than one exchange of commodities. A Fund may invest in total return commodity swaps to gain exposure to the overall commodity markets. In a total return commodity swap, a Fund will receive the price appreciation of a commodity index, a portion of the index, or a single commodity in exchange for paying an agreed-upon fee. If the commodity swap is for one period, the Fund will pay a fixed fee, established at the outset of the swap. However, if the term of the commodity swap is more than one period, with interim swap payments, the Fund will pay an adjustable or floating fee. With a “floating” rate, the fee is pegged to a base rate such as LIBOR, and is adjusted each period. Therefore, if interest rates increase over the term of the swap contract, a Fund may be required to pay a higher fee at each swap reset date.

Cross Currency Swaps. Cross currency swaps are similar to interest rate swaps, except that they involve multiple currencies. A Fund may enter into a cross currency swap when it has exposure to one currency and desires exposure to a different currency. Typically, the interest rates that determine the currency swap payments are fixed, although occasionally one or both parties may pay a floating rate of interest. Unlike an interest rate swap, however, the principal amounts are exchanged at the beginning of the contract and returned at the end of the contract. In addition to paying and receiving amounts at the beginning and termination of the agreements, both sides will have to pay in full periodically based upon the currency they have borrowed. Changes in foreign exchange currency rates and changes in interest rates, as described above, may negatively affect currency swaps.

Contracts for Differences. Contracts for differences are swap arrangements in which the parties agree that their return (or loss) will be based on the relative performance of two different groups or baskets of securities. Often, one or both baskets will be an established securities index. A Fund’s return will be based on changes in value of theoretical long futures positions in the securities comprising one basket (with an aggregate face value equal to the notional amount of the contract for differences) and theoretical short futures positions in the securities comprising the other basket. A Fund also may use actual long and short futures positions and achieve similar market exposure by netting the payment obligations of the two contracts. A Fund typically enters into contracts for differences (and analogous futures positions) when the Investment Manager believes that the basket of securities constituting the long position will outperform the basket constituting the short position. If the short basket outperforms the long basket, a Fund will realize a loss — even in circumstances when the securities in both the long and short baskets appreciate in value.

Swaptions. A swaption is an options contract on a swap agreement. These transactions give a party the right (but not the obligation) to enter into new swap agreements or to shorten, extend, cancel or otherwise modify an existing swap agreement (which are described herein) at some designated future time on specified terms, in return for payment of the purchase price (the “premium”) of the option. A Fund may write (sell) and purchase put and call swaptions to the same extent it may make use of standard options on securities or other instruments. The writer of the contract receives the premium and bears the risk of unfavorable changes in the market value on the underlying swap agreement. Swaptions can be bundled and sold as a package. These are commonly called interest rate caps, floors and collars (which are described herein).

Many swaps are complex and often valued subjectively. Many over-the-counter derivatives are complex and their valuation often requires modeling and judgment, which increases the risk of mispricing or incorrect valuation. The pricing models used may not produce valuations that are consistent with the values the Fund realizes when it closes or sells an over-the-counter derivative. Valuation risk is more pronounced when the Fund enters into over-the-counter derivatives with specialized terms because the market value of those derivatives in some cases is determined in part by reference to similar derivatives with more standardized terms. Incorrect valuations may result in increased cash payment requirements to counterparties, undercollateralization and/or errors in calculation of the Fund’s net asset value. Title VII of the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”) established a framework for the regulation of OTC swap markets; the framework outlined the joint responsibility of the CFTC and the SEC in regulating swaps. The CFTC is responsible for the regulation of swaps, the SEC is responsible for the regulation of security-based swaps and they are both jointly responsible for the regulation of mixed swaps.

It is possible that government regulation of various types of derivative instruments, including futures and swap agreements, may limit or prevent the Funds from using such instruments as a part of their investment strategy, and could ultimately prevent the Funds from being able to achieve their investment objectives. The effects of present or future legislation and regulation in this area are not known, but could be substantial and adverse. The futures markets are subject to comprehensive statutes, regulations, and margin requirements. In addition, the SEC, the CFTC and the exchanges are authorized to take extraordinary actions in the event of a market emergency, including, for example, the implementation or reduction of speculative position limits, the implementation of higher margin requirements, the establishment of daily price limits and the suspension of trading.

The regulation of swaps and futures transactions in the U.S. is a rapidly changing area of law and is subject to modification by government and judicial action. There is a possibility of future regulatory changes altering, perhaps to a material extent, the nature of an investment in a Fund or the ability of a Fund to continue to implement its investment strategies. In particular, the Dodd-Frank Act, which was signed into law in July 2010, is changing the way in which the U.S. financial system is supervised and regulated. Title VII of the Dodd-Frank Act sets forth a new legislative framework for OTC derivatives, such as swaps, in which the Funds may invest. Title VII of the Dodd-Frank Act makes broad changes to the OTC derivatives market, grants significant new authority to the SEC and the CFTC to regulate OTC derivatives and market participants, and will require clearing of many OTC derivatives transactions.

Under recently adopted rules and regulations, transactions in some types of swaps (including interest rate swaps and credit default swaps on North American and European indices) are required to be centrally cleared. In a transaction involving those swaps (“cleared derivatives”), a Fund’s counterparty is a clearing house, rather than a bank or broker. Since the Funds are not members of clearing houses and only members of a clearing house (“clearing members”) can participate directly in the clearing house, the Funds will hold cleared derivatives through accounts at clearing members. In a cleared derivatives transaction, the Funds will make payments (including margin payments) to and receive payments from a clearing house through their accounts at clearing members. Clearing members guarantee performance of their clients’ obligations to the clearing house.

In many ways, centrally cleared derivative arrangements are less favorable to mutual funds than bilateral arrangements. For example, the Funds may be required to provide greater amounts of margin for cleared derivatives positions than for bilateral derivatives transactions. Also, in contrast to a bilateral derivatives position, following a period of notice to a Fund, a clearing member generally can require termination of an existing cleared derivatives position at any time or increases in margin requirements above the margin that the clearing member required at the beginning of a transaction. Clearing houses also have broad rights to increase margin requirements for existing positions or to terminate those positions at any time. Any increase in margin requirements or termination of existing cleared derivatives positions by the clearing member or the clearing house could interfere with the ability of a Fund to pursue its investment strategy. Further, any increase in margin requirements by a clearing member could also expose a Fund to greater credit risk to its clearing member because margin for cleared derivatives transactions in excess of a clearing house’s margin requirements typically is held by the clearing member. Also, a Fund is subject to risk if it enters into a derivatives transaction that is required to be cleared (or that the Adviser expects to be cleared), and no clearing member is willing or able to clear the transaction on the Fund’s behalf. While the documentation in place between the Funds and their clearing members generally provides that the clearing members will accept for clearing all transactions submitted for clearing that are within credit limits (specified in advance) for each Fund, the Funds are still subject to the risk that no clearing member will be willing or able to clear a transaction. In those cases, the position might have to be terminated, and the Fund could lose some or all of the benefit of the position, including loss of an increase in the value of the position and/or loss of hedging protection. In addition, the documentation governing the relationship between the Funds and clearing members is developed by the clearing members and generally is less favorable to the Funds than typical bilateral derivatives documentation. For example, documentation relating to cleared derivatives generally includes a one-way indemnity by the Funds in favor of the clearing member for losses the clearing member incurs as the Funds’ clearing member and typically does not provide the Funds any remedies if the clearing member defaults or becomes insolvent. While futures contracts entail similar risks, the risks likely are more pronounced for cleared swaps due to their more limited liquidity and market history.

Some types of cleared derivatives are required to be executed on an exchange or on a swap execution facility. A swap execution facility is a trading platform where multiple market participants can execute derivatives by accepting bids and offers made by multiple other participants in the platform. While this execution requirement is designed to increase transparency and liquidity in the cleared derivatives market, trading on a swap execution facility can create additional costs and risks for the Funds. For example, swap execution facilities typically charge

fees, and if a Fund executes derivatives on a swap execution facility through a broker intermediary, the intermediary may impose fees as well. Also, a Fund may indemnify a swap execution facility, or a broker intermediary who executes cleared derivatives on a swap execution facility on the Fund’s behalf, against any losses or costs that may be incurred as a result of the Fund’s transactions on the swap execution facility.

These and other new rules and regulations could, among other things, further restrict a Fund’s ability to engage in, or increase the cost to the Fund of, derivatives transactions, for example, by making some types of derivatives no longer available to the Fund, increasing margin or capital requirements, or otherwise limiting liquidity or increasing transaction costs. These regulations are new and evolving, so their potential impact on the Funds and the financial system are not yet known. While the new regulations and the central clearing of some derivatives transactions are designed to reduce systemic risk (i.e., the risk that the interdependence of large derivatives dealers could cause a number of those dealers to suffer liquidity, solvency or other challenges simultaneously), there is no assurance that the new clearing mechanisms will achieve that result, and in the meantime, as noted above, central clearing and related requirements expose the Funds to new kinds of risks and costs.

The Investment Manager qualifies for an exclusion from the definition of a “commodity pool operator” under the CEA and has on file a notice of exclusion under CFTC Rule 4.5 with respect to the Funds. Accordingly, the Investment Manager is not subject to registration or regulation as a commodity pool operator under the CEA with respect to the Funds. To ensure that the Investment Manager remains eligible for the exclusion, each of the Funds is limited in its ability to use certain financial instruments regulated under the CEA (“commodity interests”), including futures and options on futures and certain swaps transactions. In the event that a Fund’s investments in commodity interests are not within the thresholds set forth in the exclusion, the Investment Manager may be required to register as a “commodity pool operator” with the CFTC with respect to that Fund. The Investment Manager’s eligibility to claim the exclusion with respect to a Fund will be based upon, among other things, the level and scope of a Fund’s investments in commodity interests, the purposes of such investments and the manner in which the Fund holds out its use of commodity interests. Each Fund’s ability to invest in commodity interests (including, but not limited to, futures and swaps on broad-based securities indexes and interest rates) is limited by the Investment Manager’s intention to operate the Fund in a manner that would permit the Investment Manager to continue to claim the exclusion under CFTC Rule 4.5, which may adversely affect the Fund’s total return. In the event the Investment Manager becomes unable to rely on the exclusion in Rule 4.5 and is required to register with the CFTC as a commodity pool operator with respect to a Fund, the Fund’s expenses may increase, adversely affecting that Fund’s total return. The Columbia Acorn Funds do not expect to have significant investments, if any, in commodity interests.

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 securities on a specified future date and price from the same party. 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 or Portfolio 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. The investor also could be compensated through the receipt of fee income equivalent to a lower forward price.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with mortgage dollar rolls include: Counterparty Risk, Credit Risk and Interest Rate Risk. See Information Regarding Risks.

An equity-linked note (ELN) is a debt instrument whose value is based on the value of a single equity security, basket of equity securities or an index of equity securities (each, an Underlying Equity). An ELN typically provides interest income, thereby offering a yield advantage over investing directly in an Underlying Equity. The Fund may purchase ELNs that trade on a securities exchange or those that trade on the over-the-counter markets, including Rule 144A securities. The Fund may also purchase ELNs in a privately negotiated transaction with the issuer of the ELNs (or its broker-dealer affiliate). The Fund may or may not hold an ELN until its maturity.

Equity-linked securities also 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.

Eurodollar instruments are bonds that pay interest and principal in U.S. dollars held in banks outside the United States, primarily in Europe. Eurodollar instruments are usually issued on behalf of multinational companies and foreign governments by large underwriting groups composed of banks and issuing houses from many countries. Yankee Dollar instruments are U.S. dollar-denominated bonds issued in the United States by foreign banks and corporations. These investments involve risks that are different from investments in securities issued by U.S. issuers. Eurodollar futures contracts enable purchasers to obtain a fixed rate for the lending of funds and sellers to obtain a fixed rate for borrowings. A Fund may use Eurodollar futures contracts and options thereon to hedge against changes in the LIBOR, to which many interest rate swaps and fixed income instruments are linked.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with Eurodollar and Yankee Dollar instruments include: Credit Risk, Foreign Securities Risk, Interest Rate Risk and Issuer Risk. See Information Regarding Risks.

Because investments in foreign securities usually involve currencies of foreign countries and because a Fund may hold cash and cash equivalent investments in foreign currencies, the value of a Fund’s assets as measured in U.S. dollars may be affected favorably or unfavorably by changes in currency exchange rates and exchange control regulations. Also, a Fund may incur costs in connection with conversions between various currencies. Currency exchange rates may fluctuate significantly over short periods of time, causing a Fund’s NAV to fluctuate. Currency exchange rates are generally determined by the forces of supply and demand in the foreign exchange markets, actual or anticipated changes in interest rates, and other complex factors. Currency exchange rates also can be affected by the intervention of U.S. or foreign governments or central banks, or the failure to intervene, or by currency controls or political developments.

Spot Rates and Derivative Instruments. A Fund may conduct its foreign currency exchange transactions either at the spot (cash) rate prevailing in the foreign currency exchange market or by entering into forward foreign currency exchange contracts (forward contracts). (See Permissible Fund Investments — Derivatives.) These contracts are traded in the interbank market conducted directly between currency traders (usually large commercial banks) and their customers. Because foreign currency transactions occurring in the interbank market

might involve substantially larger amounts than those involved in the use of such derivative instruments, a Fund could be disadvantaged by having to deal in the odd lot market for the underlying foreign currencies at prices that are less favorable than for round lots.

A Fund may enter into forward contracts for a variety of reasons, including for risk management (hedging) or for investment purposes.

When a Fund enters into a contract for the purchase or sale of a security denominated in a foreign currency or has been notified of a dividend or interest payment, it may desire to lock in the price of the security or the amount of the payment, usually in U.S. dollars, although it could desire to lock in the price of the security in another currency. By entering into a forward contract, a Fund would be able to protect itself against a possible loss resulting from an adverse change in the relationship between different currencies from the date the security is purchased or sold to the date on which payment is made or received or when the dividend or interest is actually received.

A Fund may enter into forward contracts when the Investment Manager believes the currency of a particular foreign country may decline in value relative to another currency. When selling currencies forward in this fashion, a Fund may seek to hedge the value of foreign securities it holds against an adverse move in exchange rates. The precise matching of forward contract amounts and the value of securities involved generally will not be possible since the future value of securities in foreign currencies more than likely will change between the date the forward contract is entered into and the date it matures. The projection of short-term currency market movements is extremely difficult and successful execution of a short-term hedging strategy is highly uncertain.

This method of protecting the value of a Fund’s securities against a decline in the value of a currency does not eliminate fluctuations in the underlying prices of the securities. It simply establishes a rate of exchange that can be achieved at some point in time. Although forward contracts can be used to minimize the risk of loss due to a decline in value of hedged currency, they will also limit any potential gain that might result should the value of such currency increase.

A Fund may also enter into forward contracts when the Investment Manager believes the currency of a particular country will increase in value relative to another currency. A Fund may buy currencies forward to gain exposure to a currency without incurring the additional costs of purchasing securities denominated in that currency.

For example, the combination of U.S. dollar-denominated instruments with long forward currency exchange contracts creates a position economically equivalent to a position in the foreign currency, in anticipation of an increase in the value of the foreign currency against the U.S. dollar. Conversely, the combination of U.S. dollar-denominated instruments with short forward currency exchange contracts is economically equivalent to borrowing the foreign currency for delivery at a specified date in the future, in anticipation of a decrease in the value of the foreign currency against the U.S. dollar.

Unanticipated changes in the currency exchange results could result in poorer performance for Funds that enter into these types of transactions.

A Fund may designate cash or securities in an amount equal to the value of the Fund’s total assets committed to consummating forward contracts entered into under the circumstance set forth above. If the value of the securities declines, additional cash or securities will be designated on a daily basis so that the value of the cash or securities will equal the amount of the Fund’s commitments on such contracts.

At maturity of a forward contract, a Fund may either deliver (if a contract to sell) or take delivery of (if a contract to buy) the foreign currency or terminate its contractual obligation by entering into an offsetting contract with the same currency trader, having the same maturity date, and covering the same amount of foreign currency.

If a Fund engages in an offsetting transaction, it will incur a gain or loss to the extent there has been movement in forward contract prices. If a Fund engages in an offsetting transaction, it may subsequently enter into a new forward contract to buy or sell the foreign currency.

Although a Fund values its assets each business day in terms of U.S. dollars, it may not intend to convert its foreign currencies into U.S. dollars on a daily basis. However, it will do so from time to time, and such conversions involve certain currency conversion costs. Although foreign exchange dealers do not charge a fee for conversion, they do realize a profit based on the difference (spread) between the prices at which they buy and sell various currencies. Thus, a dealer may offer to sell a foreign currency to a Fund at one rate, while offering a lesser rate of exchange should a Fund desire to resell that currency to the dealer.

It is possible, under certain circumstances, including entering into forward currency contracts for investment purposes, that a Fund will be required to limit or restructure its forward contract currency transactions to qualify as a “regulated investment company” under the Internal Revenue Code.

Options on Foreign Currencies. A Fund may buy put and call options and write covered call and cash-secured put options on foreign currencies for hedging purposes and to gain exposure to foreign currencies. For example, a decline in the dollar value of a foreign currency in which securities are denominated will reduce the dollar value of such securities, even if their value in the foreign currency remains constant. In order to protect against the diminutions in the value of securities, a Fund may buy put options on the foreign currency. If the value of the currency does decline, a Fund would have the right to sell the currency for a fixed amount in dollars and would thereby offset, in whole or in part, the adverse effect on its portfolio that otherwise would have resulted.

Conversely, where a change in the dollar value of a currency would increase the cost of securities a Fund plans to buy, or where a Fund would benefit from increased exposure to the currency, a Fund may buy call options on the foreign currency, giving it the right to purchase the currency for a fixed amount in dollars. The purchase of the options could offset, at least partially, the changes in exchange rates.

As in the case of other types of options, however, the benefit to a Fund derived from purchases of foreign currency options would be reduced by the amount of the premium and related transaction costs. In addition, where currency exchange rates do not move in the direction or to the extent anticipated, a Fund could sustain losses on transactions in foreign currency options that would require it to forego a portion or all of the benefits of advantageous changes in rates.

A Fund may write options on foreign currencies for similar purposes. For example, when a Fund anticipates a decline in the dollar value of foreign-denominated securities due to adverse fluctuations in exchange rates, it could, instead of purchasing a put option, write a call option on the relevant currency, giving the option holder the right to purchase that currency from the Fund for a fixed amount in dollars. If the expected decline occurs, the option would most likely not be exercised and the diminution in value of securities would be offset, at least partially, by the amount of the premium received.

Similarly, instead of purchasing a call option when a foreign currency is expected to appreciate, a Fund could write a put option on the relevant currency, giving the option holder the right to that currency from the Fund for a fixed amount in dollars. If rates move in the manner projected, the put option would expire unexercised and allow the Fund to hedge increased cost up to the amount of the premium.

As in the case of other types of options, however, the writing of a foreign currency option will constitute only a partial hedge up to the amount of the premium, and only if rates move in the expected direction. If this does not occur, the option may be exercised and the Fund would be required to buy or sell the underlying currency at a loss that may not be offset by the amount of the premium. Through the writing of options on foreign currencies, the Fund also may be required to forego all or a portion of the benefits that might otherwise have been obtained from favorable movements on exchange rates. An option written on foreign currencies is

covered if a Fund holds currency sufficient to cover the option or has an absolute and immediate right to acquire that currency without additional cash consideration upon conversion of assets denominated in that currency or exchange of other currency held in its portfolio. An option writer could lose amounts substantially in excess of its initial investments due to the margin and collateral requirements associated with such positions.

Options on foreign currencies are traded through financial institutions acting as market-makers, although foreign currency options also are traded on certain national securities exchanges, such as the Philadelphia Stock Exchange and the Chicago Board Options Exchange, subject to SEC regulation. In an over-the-counter trading environment, many of the protections afforded to exchange participants will not be available. For example, there are no daily price fluctuation limits, and adverse market movements could therefore continue to an unlimited extent over a period of time. Although the purchaser of an option cannot lose more than the amount of the premium plus related transaction costs, this entire amount could be lost.

Foreign currency option positions entered into on a national securities exchange are cleared and guaranteed by the OCC, thereby reducing the risk of counterparty default. Further, a liquid secondary market in options traded on a national securities exchange may be more readily available than in the over-the-counter market, potentially permitting a Fund to liquidate open positions at a profit prior to exercise or expiration, or to limit losses in the event of adverse market movements.

Foreign Currency Futures and Related Options. A Fund may enter into currency futures contracts to buy or sell currencies. It also may buy put and call options and write covered call and cash-secured put options on currency futures. Currency futures contracts are similar to currency forward contracts, except that they are traded on exchanges (and have margin requirements) and are standardized as to contract size and delivery date. Most currency futures call for payment of delivery in U.S. dollars. A Fund may use currency futures for the same purposes as currency forward contracts, subject to CFTC limitations.

Currency futures and options on futures values can be expected to correlate with exchange rates, but will not reflect other factors that may affect the value of the Fund’s investments. A currency hedge, for example, should protect a Yen-denominated bond against a decline in the Yen, but will not protect a Fund against price decline if the issuer’s creditworthiness deteriorates. Because the value of a Fund’s investments denominated in foreign currency will change in response to many factors other than exchange rates, it may not be possible to match the amount of a forward contract to the value of a Fund’s investments denominated in that currency over time.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with foreign currency transactions include: Foreign Currency Risk, Derivatives Risk, Interest Rate Risk and Liquidity Risk. See Information Regarding Risks.

Unless otherwise stated in a Fund’s prospectus, stocks, bonds and other securities or investments are deemed to be “foreign” based primarily on the issuer’s place of organization/incorporation, but the Fund may also consider the issuer’s domicile, its principal place of business, primary stock exchange listing, the source of its revenue, or other factors. A Fund’s investments in foreign markets may include issuers in emerging markets, as well as frontier markets, each of which carry heightened risks as compared with investments in other types of foreign markets. Frontier market countries generally have smaller economies and even less developed capital markets than typical emerging market countries (which themselves have increased investment risk relative to investing in more developed markets) and, as a result, the risks of investing in emerging market countries are magnified in frontier market countries. Foreign 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.

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.

There is 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 such shares are voted. This is referred to as “share blocking.” 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.

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 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.

Under normal conditions, the Funds’ investments in foreign companies (as a percent of total assets) are allocated as follows:

Liquidity and Trading Volume Risks of Foreign Investing. A Fund that invests a significant percentage of its assets in foreign securities may be subject to the liquidity and trading volume risks associated with international investing. Due to market conditions, including uncertainty regarding the price of a security, it may be difficult for the Fund to buy or sell foreign portfolio securities at a desirable time or price, which could result in investment losses. This risk of portfolio illiquidity is heightened with respect to small- and mid-cap securities, generally, and foreign small- and mid-cap securities in particular. The Fund may have to lower the selling price, liquidate other investments, or forego another, more appealing investment opportunity as a result of illiquidity in the markets. The Investment Manager will fair value in good faith any securities it deems to be illiquid under consistently applied procedures established by the Fund’s Board. Market conditions are always changing and vary by country and industry sector, and investing in international markets involves unique risks. In the wake of the 2007-2009 financial crisis, trading volumes in both emerging and developed international markets declined significantly and have stayed at generally reduced levels since then. Although it is difficult to accurately assess trends in trading volumes in foreign markets, because some amount of activity has migrated to alternative trading venues, a reduction in trading volumes poses challenges to the Fund. This is particularly so because the Fund focuses on small- and mid-cap companies that usually have lower trading volumes and often takes sizeable positions in portfolio companies. As a result of lower trading volumes, it may take longer to buy or sell the securities of such companies, which can exacerbate the Fund’s exposure to volatile markets. The Fund may also be limited in its ability to execute favorable trades in foreign portfolio securities in response to changes in company prices and fundamentals. If the Fund is forced to sell securities to meet redemption requests or other cash needs, or in the case of an event affecting liquidity in a particular market or markets, it may be forced to dispose of those securities under disadvantageous circumstances and at a loss. As a Fund grows in size, these considerations take on increasing significance and may adversely impact performance.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with foreign securities include: Emerging Markets Securities Risk, Foreign Currency Risk, Foreign Securities Risk, Frontier Market Risk, Geographic Concentration Risk, Issuer Risk and Market Risk. See Information Regarding Risks.

Guaranteed investment contracts, or funding agreements, are short-term, privately placed 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.

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. See Permissible Fund Investments — Illiquid Securities.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with guaranteed investment contracts (funding agreements) include: Credit Risk and Liquidity Risk. See Information Regarding Risks.

High yield or 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. High yield 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. Credit ratings issued by credit rating agencies are designed to evaluate the safety of principal and interest payments of rated securities. They do not, however, evaluate the market value risk of lower-quality securities and, therefore, may not fully reflect the true risks of an investment. In addition, credit rating agencies may or may not make timely changes in a rating to reflect changes in the economy or in the condition of the issuer that affect the market value of the securities. Consequently, credit ratings are used only as a preliminary indicator of investment quality. High yield 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.

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 high yield 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 high yield 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.

The risk of loss due to default is greater for high yield and comparable unrated securities than it is for higher rated securities because high yield 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; and (ii) sell the securities either at fair market value 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. For information regarding certain limits on the Funds’ investments in illiquid securities, restricted securities and other securities for which there is no ready market, see Fundamental and Non-Fundamental Investment Policies.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with high yield securities include: Credit Risk, Interest Rate Risk, High Yield Securities Risk and Prepayment and Extension Risk. See Information Regarding Risks.

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. Some securities are deemed to be illiquid because they are subject to contractual or legal restrictions on resale. 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 at the time of purchase. For information regarding certain limits on the Funds’ investments in illiquid securities, restricted securities and other securities for which there is no ready market, see Fundamental and Non-Fundamental Investment Policies.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with illiquid securities include: Liquidity Risk. See Information Regarding Risks.

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. 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. In circumstances when 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.

Although one or more risks described in this SAI may also apply, the risks typically associated with IPOs include: Initial Public Offering (IPO) Risk, Issuer Risk, Liquidity Risk, Market Risk and Small Company Securities Risk. See Information Regarding Risks.

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 relief currently or in the future available to a Fund, or the investment company in which a Fund invests, from the SEC. These securities include shares of other open-end investment companies (i.e., mutual funds), closed-end funds, exchange-traded funds (ETFs), UCITS funds (pooled investment vehicles established in accordance with the Undertaking for Collective Investment in Transferable Securities adopted by European Union member states) and business development companies.

Except with respect to funds structured as funds-of-funds or so-called master-feeder funds or other funds whose strategies otherwise allow such investments, 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 ETFs, which are shares of publicly traded unit investment trusts, open-end funds or depositary receipts that may be passively managed (e.g. they seek to track the performance of specific indexes or companies in related industries), or they may be actively managed. The SEC has granted orders for exemptive relief to certain ETFs that permit investments in those ETFs by certain other registered investment companies in excess of these limits.

ETFs are listed on an exchange and trade in the secondary market on a per-share basis, which allows investors to purchase and sell ETF shares at their market price throughout the day. Certain ETFs, such as passively managed ETFs, hold portfolios of securities that are designed to replicate, as closely as possible before expenses, the price and yield of a specified market index. The performance results of these ETFs will not replicate exactly the performance of the pertinent index due to transaction and other expenses, including fees to service providers borne by ETFs. ETF shares are sold and redeemed at net asset value only in large blocks called creation units. The Funds’ ability to redeem creation units may be limited by the 1940 Act, which provides that ETFs will not be obligated to redeem shares held by the Funds in an amount exceeding one percent of their total outstanding securities during any period of less than 30 days.

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. Because these investment companies may invest in other securities, they are also subject to the risks associated with a variety of investment instruments as described in this SAI.

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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with investing in the securities of other investment companies include: Exchange-Traded Fund (ETF) Risk, Investing in Other Funds Risk, Issuer Risk and Market Risk. See Information Regarding Risks.

Money market instruments include cash equivalents and short-term debt obligations, which include: (i) bank obligations, including certificates of deposit (CDs), time deposits and bankers’ acceptances, and letters of credit of banks or savings and loan associations having capital surplus and undivided profits (as of the date of its most recently published annual financial statements) in excess of $100 million (or the equivalent in the instance of a foreign branch of a U.S. bank) at the date of investment; (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 privately placed or publicly offered. A Fund may also invest in affiliated and unaffiliated money market mutual funds, which invest primarily in money market instruments. See Permissible Fund Investments — Variable- and Floating-Rate Obligations and Permissible Fund Investments — Private Placement and Other Restricted Securities for more information.

With respect to money market securities, certain U.S. Government obligations are backed or insured by the U.S. Government, its agencies or its instrumentalities. Other money market instruments are backed only by the claims paying ability or creditworthiness of the issuer.

Bankers’ acceptances are marketable short-term credit instruments used to finance the import, export, transfer or storage of goods. They are termed “accepted” when a bank unconditionally guarantees their payment at maturity.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with money market instruments include: Credit Risk, Inflation Risk, Interest Rate Risk, Issuer Risk, Money Market Fund Risk and Regulatory Risk. See Information Regarding Risks.

Mortgage-backed securities are a type of asset-backed security that 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 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.

Mortgage-backed securities may be issued or guaranteed by the Government National Mortgage Association (GNMA, also known as Ginnie Mae), the Federal National Mortgage Association (FNMA, also known as Fannie Mae), or the Federal Home Loan Mortgage Corporation (FHLMC, also known as Freddie Mac), but also may be issued or 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 that contain guarantees as to timely payment of interest and principal but that 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.

In the past, 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. There can be no assurance that these or other agencies of the government will provide such support in the future. The future status of Fannie Mae or Freddie Mac could be impacted by, among other things, the actions taken and restrictions placed on Fannie Mae or Freddie Mac by the FHFA in its role as conservator, the restrictions placed on Fannie Mae’s or Freddie Mac’s operations and activities under the senior stock purchase agreements, market responses to developments at Fannie Mae or Freddie Mac, and future legislative and regulatory action that alters the operations, ownership structure and/or mission of Fannie Mae or Freddie Mac, each of which may, in turn, impact the value of, and cash flows on, any securities guaranteed by Fannie Mae and Freddie Mac.

Stripped mortgage-backed securities are a type of mortgage-backed security that receives differing proportions of the interest and principal payments from the underlying assets. Generally, there are two classes of stripped mortgage-backed securities: Interest Only (IO) and Principal Only (PO). IOs entitle the holder to receive distributions consisting of all or a portion of the interest on the underlying pool of mortgage loans or mortgage-

backed securities. POs entitle the holder to receive distributions consisting of all or a portion of the principal of the underlying pool of mortgage loans or mortgage-backed securities. See Permissible Fund Investments — Stripped Securities for more information.

Collateralized mortgage obligations (CMOs) are hybrid mortgage-related instruments issued by special-purpose entities secured by pools of mortgage loans or other mortgage-related securities, such as mortgage pass-through securities or stripped mortgage backed securities. CMOs may be structured into multiple classes, often referred to as “tranches,” with each class bearing a different stated maturity and entitled to a different schedule for payments of principal and interest, including prepayments. Principal prepayments on collateral underlying a CMO may cause it to be retired substantially earlier than its stated maturity or final distribution dates, resulting in a loss of all or part of the premium if any has been paid. The yield characteristics of mortgage-backed securities differ from those of other debt securities. Among the differences are that interest and principal payments are made more frequently on mortgage-backed securities, usually monthly, and principal may be repaid at any time. These factors may reduce the expected yield. 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.

Commercial mortgage-backed securities (CMBS) are a specific type of mortgage-backed security collateralized by a pool of mortgages on commercial real estate.

CMO residuals are mortgage securities issued by agencies or instrumentalities of the U.S. Government or by private originators of, or investors in, mortgage loans, including savings and loan associations, homebuilders, mortgage banks, commercial banks, investment banks and special purpose entities of the foregoing. The cash flow generated by the mortgage assets underlying a series of CMOs is applied first to make required payments of principal and interest on the CMOs and second to pay the related administrative expenses and any management fee of the issuer. The residual in a CMO structure generally represents the interest in any excess cash flow remaining after making the foregoing payments. Each payment of such excess cash flow to a holder of the related CMO residual represents income and/or a return of capital. The amount of residual cash flow resulting from a CMO will depend on, among other things, the characteristics of the mortgage assets, the coupon rate of each class of CMO, prevailing interest rates, the amount of administrative expenses and the pre-payment experience on the mortgage assets. In particular, the yield to maturity on CMO residuals is extremely sensitive to pre-payments on the related underlying mortgage assets, in the same manner as an interest-only (IO) class of stripped mortgage-backed securities. In addition, if a series of a CMO includes a class that bears interest at an adjustable rate, the yield to maturity on the related CMO residual will also be extremely sensitive to changes in the level of the index upon which interest rate adjustments are based. As described below with respect to stripped mortgage-backed securities, in certain circumstances an ETF may fail to recoup fully its initial investment in a CMO residual. CMO residuals are generally purchased and sold by institutional investors through several investment banking firms acting as brokers or dealers. Transactions in CMO residuals are generally completed only after careful review of the characteristics of the securities in question. In addition, CMO residuals may, or pursuant to an exemption therefrom, may not have been registered under the 1933 Act. CMO residuals, whether or not registered under the 1933 Act, may be subject to certain restrictions on transferability, and may be deemed “illiquid” and subject to a Fund’s or a Portfolio Fund’s limitations on investment in illiquid securities.

Mortgage securities are interests in pools of mortgage-related securities that differ from other forms of debt securities, which normally provide for periodic payment of interest in fixed amounts with principal payments at maturity or specified call dates. Instead, these securities provide a monthly payment which consists of both interest and principal payments. In effect, these payments are a “pass-through” of the monthly payments made by the individual borrowers on their residential or commercial mortgage loans, net of any fees paid to the issuer or guarantor of such securities. Additional payments are caused by repayments of principal resulting from the sale of

the underlying property, refinancing or foreclosure, net of fees or costs which may be incurred. Some mortgage-related securities (such as securities issued by the GNMA) are described as “modified pass-through.” These securities entitle the holder to receive all interest and principal payments owed on the mortgage pool, net of certain fees, at the scheduled payment dates regardless of whether or not the mortgagor actually makes the payment.

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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with mortgage- and asset-backed securities include: Credit Risk, Interest Rate Risk, Liquidity Risk, Mortgage-Backed and Other Asset-Backed Securities Risk, Prepayment and Extension Risk and Reinvestment Risk. See Information Regarding Risks.

Municipal securities include debt obligations issued by governmental entities, including states, political subdivisions, agencies, instrumentalities, and authorities, as well as U.S. territories (such as Guam and Puerto Rico) and their political subdivisions, agencies, instrumentalities and authorities, 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 may include municipal bonds, municipal notes and municipal leases, which are described below. 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 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 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.

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 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 or Portfolio 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 or Portfolio 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 and may take the form of a lease, an installment purchase, or a conditional sales contract. They are issued by state and local governments and authorities to acquire land, equipment, and facilities. An investor may purchase these obligations directly, or it may purchase participation interests in such obligations. In general, municipal lease obligations are unrated, in which case they will be determined by the Investment Manager or a Portfolio Fund’s investment adviser to be of comparable quality at the time of purchase to rated instruments that may be acquired by a Fund or Portfolio 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.

Municipal leases may be subject to greater risks than general obligation or revenue bonds. State constitutions and statutes set forth requirements that states or municipalities must meet in order to issue municipal obligations. Municipal leases may contain a covenant by the state or municipality to budget for and make payments due under the obligation. Certain municipal leases may, however, provide that the issuer is not obligated to make payments on the obligation in future years unless funds have been appropriated for this purpose each year.

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 or Portfolio 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.

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. The municipal bond market is characterized by a large number of different issuers, many having smaller sized bond issues, and a wide choice of different maturities within each issue. For these reasons, most municipal bonds do not trade on a daily basis and many trade only rarely. Because many of these bonds trade infrequently, the spread between the bid and offer may be wider and the time needed to develop a bid or an offer may be longer than for other security markets. See Appendix A for a discussion of securities ratings. (See Permissible Fund Investments — Debt Obligations.)

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 or a Portfolio 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 or a Portfolio 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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with standby commitments include: Counterparty Risk, Market Risk and Municipal Securities Risk. See Information Regarding Risks.

Taxable Municipal Obligations. Interest or other investment return is subject to federal income tax for certain types of municipal obligations for a variety of reasons. These municipal obligations do not qualify for the federal income tax exemption because (a) they did not receive necessary authorization for tax-exempt treatment from state or local government authorities, (b) they exceed certain regulatory limitations on the cost of issuance for tax-exempt financing or (c) they finance public or private activities that do not qualify for the federal income tax exemption. These non-qualifying activities might include, for example, certain types of multi-family housing, certain professional and local sports facilities, refinancing of certain municipal debt, and borrowing to replenish a municipality’s underfunded pension plan.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with municipal securities include: Credit Risk, Inflation Risk, Interest Rate Risk, Market Risk and Municipal Securities Risk. See Information Regarding Risks.

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 or Portfolio 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 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.

Loan participations also are a type of participation interest. Loans, loan participations and interests in securitized loan pools are interests in amounts owed by a corporate, governmental or other borrower to a lender or consortium of lenders (typically banks, insurance companies, investment banks, government agencies or international agencies).

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with loan participations include: Confidential Information Access Risk, Credit Risk and Interest Rate Risk. See Information Regarding Risks.

A Fund may invest in securities issued by publicly traded partnerships (PTPs) or master limited partnerships (MLPs) or limited liability companies (together, referred to herein as PTPs/MLPs). These entities are limited partnerships or limited liability companies that may be publicly traded on stock exchanges or markets such as the NYSE, the NYSE Alternext US LLC (NYSE Alternext) (formerly the American Stock Exchange) and NASDAQ. PTPs/MLPs often own businesses or properties relating to energy, natural resources or real estate, or may be involved in the film industry or research and development activities. Generally PTPs/MLPs are operated under the supervision of one or more managing partners or members. Limited partners, unit holders, or members (such as a fund that invests in a partnership) are not involved in the day-to-day management of the company. Limited partners, unit holders, or members are allocated income and capital gains associated with the partnership project in accordance with the terms of the partnership or limited liability company agreement.

At times PTPs/MLPs may potentially offer relatively high yields compared to common stocks. Because PTPs/MLPs are generally treated as partnerships or similar limited liability “pass-through” entities for tax purposes, they do not ordinarily pay income taxes, but pass their earnings on to unit holders (except in the case of some publicly traded firms that may be taxed as corporations). For tax purposes, unit holders may initially be deemed to receive only a portion of the distributions attributed to them because certain other portions may be attributed to the repayment of initial investments and may thereby lower the cost basis of the units or shares owned by unit holders. As a result, unit holders may effectively defer taxation on the receipt of some distributions until they sell their units. These tax consequences may differ for different types of entities.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with partnership securities include: Interest Rate Risk, Issuer Risk, Liquidity Risk and Market Risk. See Information Regarding Risks.

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. The price of a preferred stock is generally determined by earnings, type of products or services, projected growth rates, experience of management, liquidity, and general market conditions of the markets in which the stock trades. 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. An APS is distinguished from standard preferred stock because its dividends change from time to time. Shares typically are bought and sold at face values generally ranging from $100,000 to $500,000 per share. Holders of APS may not be able to sell their shares if an auction fails, such as when there are more shares of APS for sale at an auction than there are purchase bids.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with preferred stock include: Convertible Securities Risk, Issuer Risk, Liquidity Risk and Market Risk. See Information Regarding Risks.

Private placement securities are securities that have been privately placed and are not registered under the 1933 Act. They are generally eligible for sale only to certain eligible investors. Private 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, high yield 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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with private placement and other restricted securities include: Issuer Risk, Liquidity Risk, Market Risk and Confidential Information Access Risk. See Information Regarding Risks.

Real estate investment trusts (REITs) are pooled investment vehicles that manage a portfolio of real estate or real estate related loans to earn profits for their shareholders. REITs are generally classified as equity REITs, mortgage REITs or a combination of equity and mortgage REITs. Equity REITs invest the majority of their assets directly in real property, such as shopping centers, nursing homes, office buildings, apartment complexes, and hotels, and derive income primarily from the collection of rents. Equity REITs can also realize capital gains by selling properties that have appreciated in value. Mortgage REITs invest the majority of their assets in real estate mortgages and derive income from the collection of interest payments. REITs can be subject to extreme volatility due to fluctuations in the demand for real estate, changes in interest rates, and adverse economic conditions.

Partnership units of real estate and other types of companies sometimes are organized as master limited partnerships in which ownership interests are publicly traded.

Similar to investment companies, REITs are not taxed on income distributed to shareholders provided they comply with certain requirements under the Code. The failure of a REIT to continue to qualify as a REIT for tax purposes can materially affect its value. A Fund will indirectly bear its proportionate share of any expenses paid by a REIT in which it invests. REITs often do not provide complete tax information until after the calendar year-end. Consequently, because of the delay, it may be necessary for a Fund investing in REITs to request permission to extend the deadline for issuance of Forms 1099-DIV beyond January 31. In the alternative, amended Forms 1099-DIV may be sent.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with REITs include: Interest Rate Risk, Issuer Risk, Market Risk and Real Estate-Related Investment Risk. See Information Regarding Risks.

Repurchase agreements are agreements under which a Fund acquires a security for a relatively short period of time (usually within seven days) subject to the obligation of a seller to repurchase and a Fund to resell such security at a fixed time and price (representing the Fund’s cost plus interest). The repurchase agreement specifies the yield during the purchaser’s holding period. Repurchase agreements also may be viewed as loans made by a Fund that are collateralized by the securities subject to repurchase, which may consist of a variety of security types. A Fund typically will enter into repurchase agreements only with commercial banks, registered broker-dealers and the Fixed Income Clearing Corporation. 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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with repurchase agreements include: Counterparty Risk, Credit Risk, Issuer Risk, Market Risk and Repurchase Agreements Risk. See Information Regarding Risks.

Reverse repurchase agreements are agreements under which a Fund temporarily transfers possession of a portfolio instrument to another party, such as a bank or broker-dealer, in return for cash. At the same time, the Fund agrees to repurchase the instrument at an agreed-upon time (normally within 7 days) and price which reflects an interest payment. A Fund generally retains the right to interest and principal payments on the security. Reverse repurchase agreements also may be viewed as borrowings made by a Fund.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with reverse repurchase agreements include: Credit Risk, Interest Rate Risk, Issuer Risk, Market Risk and Reverse Repurchase Agreements Risk. See Information Regarding Risks.

Sovereign debt obligations are issued or guaranteed by foreign governments or their agencies. It may be in the form of conventional securities or other types of debt instruments such as loans or loan participations. 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 the 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 a default.

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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with sovereign debt include: Credit Risk, Emerging Markets Securities Risk, Foreign Securities Risk, Issuer Risk and Market Risk. See Information Regarding Risks.

Stripped securities are the separate income or principal payments of a debt security and 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, Separate Trading of Registered Interest and Principal Securities (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 (TIGERs) are U.S. Treasury securities stripped by brokers. Stripped mortgage-backed securities (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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with stripped securities include: Credit Risk, Interest Rate Risk, Liquidity Risk, Prepayment and Extension Risk and Stripped Securities Risk. See Information Regarding Risks.

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 agencies or instrumentalities established or sponsored by the U.S. Government. U.S. Treasury obligations and securities issued or guaranteed by various agencies or instrumentalities 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 structured as fixed-, variable- or floating-rate obligations. See Permissible Fund Investments — Variable- and Floating-Rate Obligations for more information.

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, instrumentalities and sponsored enterprises historically have involved limited risk of loss of principal if held to maturity. However, no assurance can be given that the U.S. Government would provide financial support to any of these entities if it is not obligated to do so by law.

Government-sponsored entities issuing securities include privately owned, publicly chartered entities created to reduce borrowing costs for certain sectors of the economy, such as farmers, homeowners, and students. They include the Federal Farm Credit Bank System, Farm Credit Financial Assistance Corporation, Fannie Mae, Freddie Mac, Student Loan Marketing Association (SLMA), and Resolution Trust Corporation (RTC). Government-sponsored entities may issue discount notes (with maturities ranging from overnight to 360 days) and bonds. On Sept. 7, 2008, the Federal Housing Finance Agency (FHFA), an agency of the U.S. Government, placed Fannie Mae and Freddie Mac into conservatorship, a statutory process with the objective of returning the entities to normal business operations. FHFA will act as the conservator to operate the enterprises until they are stabilized.

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. The long-term impact of the downgrade is uncertain. See Appendix A for a description of securities ratings.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with U.S. Government and related obligations include: Credit Risk, Inflation Risk, Interest Rate Risk, Prepayment and Extension Risk, Reinvestment Risk and U.S. Government Obligations Risk. See Information Regarding Risks.

Variable- and floating-rate obligations are debt instruments that 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. Variable- or floating-rate securities frequently include a demand feature enabling the holder to sell the securities to the issuer at par. In many cases, the demand feature can be exercised at any time. Some securities that do not have variable or floating interest rates may be accompanied by puts producing similar results and price characteristics. Variable-rate demand notes include master demand notes that are obligations that permit the investor to invest fluctuating amounts, which may change daily without penalty, pursuant to direct arrangements between the investor (as lender), and the borrower. The interest rates on these notes fluctuate. The issuer of such obligations normally has a corresponding right, after a given period, to prepay in its discretion the outstanding principal amount of the obligations plus accrued interest upon a specified number of days’ notice to the holders of such obligations. Because these obligations are direct lending arrangements between the lender and borrower, it is not contemplated that such instruments generally will be traded. There generally is not an established secondary market for these obligations. Accordingly, where these obligations are not secured by letters of credit or other credit support arrangements, the lender’s right to redeem is dependent on the ability of the borrower to pay principal and interest on demand. Such obligations frequently are not rated by credit rating agencies and may involve heightened risk of default by the issuer. Asset-backed securities, bank obligations, convertible securities, corporate debt securities, foreign securities, high yield securities, money market instruments, mortgage-backed securities, 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.

Most floating rate loans are acquired directly from the agent bank or from another holder of the loan by assignment. Most such loans are secured, and most impose restrictive covenants on the borrower. These loans are typically made by a syndicate of banks and institutional investors, represented by an agent bank which has negotiated and structured the loan and which is responsible generally for collecting interest, principal, and other amounts from the borrower on its own behalf and on behalf of the other lending institutions in the syndicate, and for enforcing its rights and the rights of the syndicate against the borrower. Each of the lending institutions, including the agent bank, lends to the borrower a portion of the total amount of the loan, and retains the corresponding interest in the loan. Floating rate loans may include delayed draw term loans and prefunded or synthetic letters of credit.

A Fund’s or a Portfolio Fund’s ability to receive payments of principal and interest and other amounts in connection with loans held by it will depend primarily on the financial condition of the borrower. The failure by the Fund or Portfolio Fund to receive scheduled interest or principal payments on a loan would adversely affect the income of the Fund or Portfolio Fund and would likely reduce the value of its assets, which would be reflected in a reduction in the Fund’s or Portfolio Fund’s net asset value. Banks and other lending institutions generally perform a credit analysis of the borrower before originating a loan or purchasing an assignment in a loan. In selecting the loans in which the Fund or Portfolio Fund will invest, however, the Investment Manager or

a Portfolio Fund’s investment adviser will not rely on that credit analysis of the agent bank, but will perform its own investment analysis of the borrowers. The Investment Manager’s analysis or the analysis of a Portfolio Fund’s investment adviser may include consideration of the borrower’s financial strength and managerial experience, debt coverage, additional borrowing requirements or debt maturity schedules, changing financial conditions, and responsiveness to changes in business conditions and interest rates. Investments in loans may be of any quality, including “distressed” loans, and will be subject to the Fund’s or Portfolio Fund’s credit quality policy.

Loans may be structured in different forms, including assignments and participations. In an assignment, a Fund or Portfolio Fund purchases an assignment of a portion of a lender’s interest in a loan. In this case, the Fund or Portfolio Fund may be required generally to rely upon the assigning bank to demand payment and enforce its rights against the borrower, but would otherwise be entitled to all of such bank’s rights in the loan.

The borrower of a loan may, either at its own election or pursuant to terms of the loan documentation, prepay amounts of the loan from time to time. There is no assurance that a Fund or Portfolio Fund will be able to reinvest the proceeds of any loan prepayment at the same interest rate or on the same terms as those of the original loan.

Corporate loans in which a Fund or Portfolio Fund may purchase a loan assignment are made generally to finance internal growth, mergers, acquisitions, recapitalizations, stock repurchases, leveraged buy-outs, dividend payments to sponsors and other corporate activities. The highly leveraged capital structure of certain borrowers may make such loans especially vulnerable to adverse changes in economic or market conditions. The Fund or Portfolio Fund may hold investments in loans for a very short period of time when opportunities to resell the investments that the Investment Manager or a Portfolio Fund’s investment adviser believes are attractive arise.

Certain of the loans acquired by a Fund or Portfolio Fund may involve revolving credit facilities under which a borrower may from time to time borrow and repay amounts up to the maximum amount of the facility. In such cases, the Fund or Portfolio Fund would have an obligation to advance its portion of such additional borrowings upon the terms specified in the loan assignment. To the extent that the Fund or Portfolio Fund is committed to make additional loans under such an assignment, it will at all times designate cash or securities in an amount sufficient to meet such commitments.

Notwithstanding its intention in certain situations to not receive material, non-public information with respect to its management of investments in floating rate loans, the Investment Manager or a Portfolio Fund’s investment adviser may from time to time come into possession of material, non-public information about the issuers of loans that may be held in a Fund’s or Portfolio Fund’s portfolio. Possession of such information may in some instances occur despite the Investment Manager’s efforts or the efforts of a Portfolio Fund’s investment adviser to avoid such possession, but in other instances the Investment Manager or a Portfolio Fund’s investment adviser may choose to receive such information (for example, in connection with participation in a creditors’ committee with respect to a financially distressed issuer). As, and to the extent, required by applicable law, the Investment Manager’s ability or the ability of a Portfolio Fund’s investment adviser to trade in these loans for the account of the Fund or Portfolio Fund could potentially be limited by its possession of such information. Such limitations on the Investment Manager’s ability or the ability of a Portfolio Fund’s investment adviser to trade could have an adverse effect on the Fund or Portfolio Fund by, for example, preventing the Fund or Portfolio Fund from selling a loan that is experiencing a material decline in value. In some instances, these trading restrictions could continue in effect for a substantial period of time.

In some instances, other accounts managed by the Investment Manager or a Portfolio Fund’s investment adviser may hold other securities issued by borrowers whose floating rate loans may be held in a Fund’s or Portfolio Fund’s portfolio. These other securities may include, for example, debt securities that are subordinate to the floating rate loans held in the Fund’s or Portfolio Fund’s portfolio, convertible debt or common or preferred equity securities. In certain circumstances, such as if the credit quality of the issuer deteriorates, the interests of holders of

these other securities may conflict with the interests of the holders of the issuer’s floating rate loans. In such cases, the Investment Manager or a Portfolio Fund’s investment adviser may owe conflicting fiduciary duties to the Fund or Portfolio Fund and other client accounts. The Investment Manager or a Portfolio Fund’s investment adviser will endeavor to carry out its obligations to all of its clients to the fullest extent possible, recognizing that in some cases certain clients may achieve a lower economic return, as a result of these conflicting client interests, than if the Investment Manager’s client account or that of a Portfolio Fund’s investment adviser collectively held only a single category of the issuer’s securities.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with variable- or floating-rate obligations include: Counterparty Risk, Credit Risk, Interest Rate Risk, Liquidity Risk and Prepayment and Extension Risk. See Information Regarding Risks.

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 do not carry with them the right to dividends or voting rights and they do not represent any rights in the assets of the issuer. Warrants may be considered to have more speculative characteristics than certain other types of investments. In addition, the value of a warrant does not necessarily change with the value of the underlying securities, and a warrant ceases to have value if it is not exercised prior to its expiration date, if any. The potential exercise price of warrants or rights may exceed their market price, such as when there is no movement in the market price or the market price of the common stock declines.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with warrants and rights include: Convertible Securities Risk, Counterparty Risk, Credit Risk, Issuer Risk and Market Risk. See Information Regarding Risks.

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 after the customary settlement period for that type of security. Normally, the settlement date occurs within 45 days of the purchase although in some cases settlement may take longer. The investor does not pay for the securities or receive dividends or interest on them until the contractual settlement date. When engaging in when-issued, delayed delivery and forward commitment transactions, a Fund typically will designate liquid assets 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 to close out the transaction prior to its completion. In such cases, a Fund may realize short-term gains or losses.

To Be Announced Securities (TBAs). As with other delayed delivery transactions, a seller agrees to issue a TBA security at a future date. However, the seller does not specify the particular securities to be delivered. Instead, the Fund agrees to accept any security that meets specified terms. For example, in a TBA mortgage-backed security transaction, the Fund and the seller would agree upon the issuer, interest rate and terms of the underlying mortgages. The seller would not identify the specific underlying mortgages until it issues the security. TBA mortgage-backed securities increase market risks because the underlying mortgages may be less favorable than anticipated by the Fund. See Types of Investments — Mortgage-Backed Securities and — Asset-Backed Securities.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with when-issued, delayed delivery and forward commitment transactions include: Counterparty Risk, Credit Risk and Market Risk. See Information Regarding Risks.

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, high yield securities, mortgage-backed securities, municipal 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 or STRIPS. 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.

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 that gradually increases over time. 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 typically 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.

Although one or more of the other risks described in this SAI may also apply, the risks typically associated with zero-coupon, step-coupon and pay-in-kind securities include: Credit Risk, Interest Rate Risk and Zero-Coupon Bonds Risk. See Information Regarding Risks.

The following is a summary of risks of investing in the Funds and the risk characteristics associated with the various types of securities in which the Funds and the Portfolio Funds are permitted to invest. In this section the term “Fund” refers to a Fund or a Portfolio Fund, except where otherwise indicated. A Fund’s risk profile is largely determined by its primary portfolio holdings and principal investment strategies. Each Fund’s principal investment strategies and principal risks are described in its prospectus.

As discussed above, the Funds are permitted to invest in certain types of securities beyond those described in their principal investment strategies. The Funds are thus subject to the risks associated with these securities and strategies. One or more of the following risks may be associated with an investment in a Fund:

Each Fund is actively managed and its performance therefore will reflect, in part, the ability of the Investment Manager to make investment decisions that will achieve the Fund’s investment objective. Due to its active management, a Fund could underperform its benchmark index and/or other funds with similar investment objectives and/or strategies.

For any Fund that uses an asset allocation strategy in pursuit of its investment objective, there is a risk that the Fund’s allocation among asset classes, investments, managers, strategies and/or investment styles will cause the Fund’s shares to lose value or cause the Fund to underperform other funds with a similar investment objective and/or strategies, or that the investments themselves will not produce the returns expected.

The value of a Fund’s asset-backed securities may be affected by, among other things, changes in interest rates, factors concerning the interests in and structure of the issuer or the originator of the receivables, the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements, or the market’s assessment of the quality of underlying assets. Asset-backed securities represent interests in, or are backed by, pools of receivables such as credit card, auto, student and home equity loans. They may also be backed by securities backed by these types of loans and others, such as mortgage loans. Asset-backed securities can have a fixed or an adjustable rate. Most asset-backed securities are subject to prepayment risk, which is the possibility that the underlying debt may be refinanced or prepaid prior to maturity during periods of declining or low interest rates, causing a Fund to have to reinvest the money received in securities that have lower yields. In addition, the impact of prepayments on the value of asset-backed securities may be difficult to predict and may result in greater volatility. Rising or high interest rates tend to extend the duration of asset-backed securities, resulting in valuations that are volatile and sensitive to changes in interest rates.

The amount of the distributions paid by a Fund will vary and generally depends on the amount of interest income and/or dividends received by the Fund on the securities it holds. A Fund may not be able to pay distributions or may have to reduce its distribution level if the interest income and/or dividends the Fund receives from its investments decline.

In many instances, issuers of floating rate loans and private placements offer to furnish material, non-public information (Confidential Information) to prospective purchasers or holders of the issuer’s floating rate loans to help potential investors assess the value of the loan. The Investment Manager and its affiliates, including the investment adviser to the Portfolio Funds, may avoid the receipt of Confidential Information about the issuers of floating rate loans being considered for acquisition by a Fund or Portfolio Fund, or held by a Fund or Portfolio Fund. A decision not to receive Confidential Information from these issuers may disadvantage a by a Fund or Portfolio Fund as compared to other floating rate loan investors, and may adversely affect the price the Fund or the Portfolio Fund pays for the loans it purchases, or the price at which the Fund sells the loans. Further, in situations when holders of floating rate loans are asked, for example, to grant consents, waivers or amendments, the ability to assess the desirability of such consents, waivers or amendments may be compromised. For these and other reasons, it is possible that the decision not to receive Confidential Information could adversely affect a Fund’s or a Portfolio Fund’s performance.

Convertible securities are subject to the usual risks associated with debt securities, such as interest rate risk (the risk of losses attributable to changes in interest rates) and credit risk (the risk that the issuer of a debt security will default or otherwise become unable, or be perceived to be unable or unwilling, to honor a financial obligation, such as making payments to a Fund when due). Convertible securities also react to changes in the value of the common stock into which they convert, and are thus subject to market risk (the risk that the market values of securities or other investments that a Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise). 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 Fund may be forced to convert a convertible security before it otherwise would choose to do so, which may decrease a Fund’s return.

The risk exists that a counterparty to a financial instrument held by a Fund or by a special purpose or structured vehicle in which the Fund invests may become insolvent or otherwise fail to perform its obligations due to financial difficulties, including making payments to the Fund. A Fund may obtain no or limited recovery in a bankruptcy or other organizational proceedings, and any recovery may be significantly delayed. Transactions that a Fund enters into may involve counterparties in the financial services sector and, as a result, events affecting the financial services sector may cause the Fund’s share value to fluctuate.

The value of loans or fixed-income securities, or other instruments or assets, may decline if the borrower or the issuer thereof defaults or otherwise becomes unable or unwilling, or is perceived to be unable or unwilling, to honor its financial obligations, such as making payments to a Fund when due. Various factors could affect the actual or perceived willingness or ability of the borrower or the issuer to make timely interest or principal payments, including changes in the financial condition of the borrower or the issuer or in general economic conditions. Fixed-income 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 fixed-income 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. Rating agencies assign credit ratings to certain loans and fixed-income securities to indicate their credit risk. Lower quality or unrated securities held by a Fund may present increased credit risk as compared to higher-rated securities. Non-investment grade loans or fixed-income securities (commonly called “high yield” or “junk”) are subject to greater price fluctuations and are more likely to experience a default than investment grade loans or securities and therefore may expose a Fund to increased credit risk. If a Fund purchases unrated loans or fixed-income securities, or if the ratings of securities held by the Fund are lowered after purchase, the Fund will depend on analysis of credit risk more heavily than usual. If the issuer of a loan declares bankruptcy or is declared bankrupt, there may be a delay before a Fund can act on the collateral securing the loan, which may adversely affect the Fund. Further, there is a risk that a court could take action with respect to a loan that is adverse to the holders of the loan. Such actions may include invalidating the loan, the lien on the collateral, the priority status of the loan, or ordering the refund of interest previously paid by the borrower. Any such actions by a court could adversely affect a Fund’s performance. A default or expected default of a loan could also make it difficult for a Fund to sell the loan at a price approximating the value previously placed on it. In order to enforce its rights in the event of a default, bankruptcy or similar situation, a Fund may be required to retain legal or similar counsel. This may increase a Fund’s operating expenses and adversely affect its NAV. Loans that have a lower priority for repayment in an issuer’s capital structure may involve a higher degree of overall risk than more senior loans of the same borrower.

Information technology (IT) systems and digital data underlie most of the Funds’ operations. As a result, the Funds and their primary service providers (the Investment Manager, the Administrator, the Sub-Administrator, the Transfer Agent and the Distributor, all affiliates of Ameriprise Financial, and the Funds’ custodian and sub-transfer agent) as well as the Funds’ other service providers, including Selling Agents, and the vendors of each (collectively Service Providers) are exposed to the risk that their operations and Fund data in their possession may be compromised by internal and external cybersecurity failures, breaches or attacks (Cyber Risk). The Funds and their shareholders could be negatively impacted as a result.

Losses to the Funds may result from malicious or criminal cyber attacks. Cyber attacks include actions taken to: (i) steal or corrupt data maintained online or digitally; (ii) gain unauthorized access to or release of confidential information; (iii) shut down a Fund or a Service Provider’s operations or website through denial-of-service attacks; or (iv) otherwise disrupt normal business operations. However, events arising from human error, faulty or inadequately implemented policies and procedures or other systems failures may have effects similar to those caused by deliberate cyber attacks.

Successful cyber attacks or other cyber failures or events affecting the Funds or Service Providers may adversely impact a Fund or its shareholders or cause an investment in the Fund to lose value. For instance, these events may interfere with the processing of shareholder transactions, impact a Fund’s ability to calculate its NAV, cause the release of private shareholder information or confidential Fund information, impede trading, or cause reputational damage. They could also subject the Funds or Service Providers to regulatory fines, penalties or financial losses, reimbursement or other compensation costs, and/or additional compliance costs. Insurance protection and contractual indemnification provisions may be insufficient or unavailable to cover these losses. Service Providers may also incur significant costs to manage and control Cyber Risk, which costs may be passed through to the Funds, reducing returns to shareholders.

While the Funds, and Ameriprise Financial and its affiliates that support the Funds, have established IT and data security programs and have in place business continuity plans and other systems designed to mitigate losses and Cyber Risk, there are inherent limitations to such plans and systems, including the possibility that certain risks have not been identified or that cyber attacks may be highly sophisticated, and there can be no assurance that the programs, plans and systems in place will prevent a cyber attack or otherwise prevent cyber losses. Similarly, while Ameriprise Financial and its affiliates that support the Funds have implemented a vendor risk assessment oversight program that seeks to assess the strength of the cybersecurity measures in place at Service Providers that perform key operational functions for the Funds and/or have access to sensitive and confidential data, there can be no assurance that all vulnerabilities will be adequately identified or that these measures will prevent cyber related losses.

Cyber Risk is also present for issuers of securities or other instruments in which the Funds invest, which could result in material adverse consequences for such issuers, and may cause the Funds’ investment in such issuers to lose money.

Depositary receipts are receipts issued by a bank or trust company reflecting ownership of underlying securities issued by foreign companies. Some foreign securities are traded in the form of American Depositary Receipts (ADRs). Depositary receipts involve risks similar to the risks associated with investments in foreign securities, including those risks specific to the particular country, which may be related to the particular political, regulatory, economic, social and other conditions or events occurring in the country and fluctuations in its currency, as well as market risk tied to the underlying foreign company. In addition, ADR holders may have limited voting rights, may not have the same rights afforded typical company stockholders in the event of a corporate action such as an acquisition, merger or rights offering and may experience difficulty in receiving company stockholder communications. A potential conflict of interest exists to the extent that a Fund invests in ADRs for which a Fund’s custodian serves as depository bank.

Derivatives are financial instruments whose value depends on, or is derived from, the value of other underlying assets. Losses involving derivative instruments may be substantial, because a relatively small movement in the price of an underlying security, instrument, commodity, currency or index may result in a substantial loss for a Fund. In addition to the potential for increased losses, the use of derivative instruments may lead to increased volatility for a Fund. Derivative investments will typically increase a Fund’s exposure to principal risks to which it is otherwise exposed, and may expose the Fund to additional risks. Depending on the type and purpose of a Fund’s derivative investments, these risks may include correlation risk (there may be an imperfect correlation between the hedge and the opposite position, which is related to hedging risk), counterparty risk (the counterparty to the instrument may not perform or be able to perform in accordance with the terms of the instrument), leverage risk (losses from the derivative instrument may be greater than the amount invested in the derivative instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), and/or liquidity risk (it may not be possible for a Fund to liquidate the instrument at an advantageous time or price), each of which may result in significant losses for a Fund.

Derivatives Risk/Credit Default Swaps Risk. The use of credit default swaps is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. A credit default swap enables an investor to buy or sell protection against a credit event, such as an issuer’s failure to make timely payments of interest or principal, bankruptcy or restructuring. A credit default swap may be embedded within a structured note or other derivative instrument. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for a Fund. Swaps can involve greater risks than direct investment in the underlying securities, because swaps, among other factors, may be leveraged (creating leverage risk, the risk that losses from the derivative instrument may be greater than the amount invested in the derivative instrument) and subject a Fund to counterparty risk (the risk that the counterparty to the instrument will not perform or be unable to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), pricing risk (the risk that swaps may be difficult to value) and liquidity risk (it may not be possible for a Fund to liquidate a swap position at an advantageous time or price), each of which may result in significant losses for a Fund. If a Fund is selling credit protection, there is a risk that a credit event will occur and that the Fund will have to pay the counterparty. If a Fund is buying credit protection, there is a risk that no credit event will occur.

Derivatives Risk/Contracts for Difference Risk. Contracts for differences are swap arrangements in which the parties agree that their return (or loss) will be based on the relative performance of two different groups or baskets of securities or other instruments. Often, one or both baskets will be an established securities index. A Fund’s return will be based on changes in value of theoretical long futures positions in the securities comprising one basket (with an aggregate face value equal to the notional amount of the contract for differences) and theoretical short futures positions in the securities comprising the other basket. A Fund also may use actual long and short futures positions and achieve similar market exposure by netting the payment obligations of the two contracts. If the short basket outperforms the long basket, a Fund will realize a loss — even in circumstances when the securities in both the long and short baskets appreciate in value.

Derivatives Risk/Equity-Linked Notes Risk. An equity-linked note (ELN) is a debt instrument whose value is based on the value of a single equity security, basket of equity securities or an index of equity securities (each, an Underlying Equity). An ELN typically provides interest income, thereby offering a yield advantage over investing directly in an Underlying Equity. A Fund may purchase ELNs that trade on a securities exchange or those that trade on the over-the-counter markets, including securities offered and sold under Rule 144A of the Securities Act of 1933, as amended. A Fund may also purchase an ELN in a privately negotiated transaction with the issuer of the ELN (or its broker-dealer affiliate). A Fund’s investment in ELNs has the potential to lead to significant losses because ELNs are subject to the market and volatility risks associated with their Underlying Equity, and to additional risks not typically associated with investments in listed equity securities, such as

liquidity risk, credit risk of the issuer and concentration risk. The liquidity of unlisted ELNs is normally determined by the willingness of the issuer to make a market in the ELN. While a Fund will seek to purchase ELNs only from issuers that it believes to be willing to, and capable of, repurchasing the ELN at a reasonable price, there can be no assurance that a Fund will be able to sell any ELN at such a price or at all. This may impair a Fund’s ability to enter into other transactions at a time when doing so might be advantageous. In addition, because ELNs often take the form of unsecured notes of the issuer, a Fund would be subject to the risk that the issuer may default on its obligations under the ELN, thereby subjecting the Fund to the further risk of being too concentrated in the securities (including ELNs) of that issuer. A Fund may or may not hold an ELN until its maturity.

Derivatives Risk/Forward Foreign Currency Contracts Risk. The use of these derivatives is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. These instruments are a type of derivative contract, whereby a Fund may agree to buy or sell a country’s or region’s currency at a specific price on a specific date in the future. These instruments may fall in value (sometimes dramatically) due to foreign market downswings or foreign currency value fluctuations, subjecting a Fund to foreign currency risk (the risk that Fund performance may be negatively impacted by foreign currency strength or weakness relative to the U.S. dollar, particularly if a Fund exposes a significant percentage of its assets to currencies other than the U.S. dollar). The effectiveness of any currency hedging strategy by a Fund may be reduced by a Fund’s inability to precisely match forward contract amounts and the value of securities involved. Forward foreign currency contracts used for hedging may also limit any potential gain that might result from an increase or decrease in the value of the currency. Unanticipated changes in the currency markets that are greater in magnitude or directionally different than those anticipated could result in reduced performance for a Fund or losses. At or prior to maturity of a forward contract, a Fund may enter into an offsetting contract and may incur a loss to the extent there has been movement in forward contract prices. When a Fund converts its foreign currencies into U.S. dollars, it may incur currency conversion costs due to the spread between the prices at which it may buy and sell various currencies in the market. Investment in these instruments also subjects a Fund, among other factors, to counterparty risk (the risk that the counterparty to the instrument will not perform or will be unable to perform in accordance with the terms of the instrument) and leverage risk (i.e., the risk that losses from the derivative instrument may be greater than the amount invested in the derivative instruments). A Fund’s strategy of investing in these instruments may not be successful and the Fund may experience significant losses as a result.

Derivatives Risk/Forward Interest Rate Agreements Risk. Under forward interest rate agreements, the buyer locks in an interest rate at a future settlement date. If the interest rate on the settlement date exceeds the lock rate, the buyer pays the seller the difference between the two rates (based on the notional value of the agreement). If the lock rate exceeds the interest rate on the settlement date, the seller pays the buyer the difference between the two rates (based on the notional value of the agreement). A Fund may act as a buyer or a seller. Investment in these instruments subjects a Fund to risks, including counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains) and interest rate risk (the risk of losses attributable to changes in interest rates), each of which may result in significant losses for a Fund.

Derivatives Risk/Futures Contracts Risk. The use of futures contracts is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. A futures contract is a sales contract between a buyer (holding the “long” position) and a seller (holding the “short” position) for an asset with delivery deferred until a future date. The buyer agrees to pay a fixed price at the agreed future date and the seller agrees to deliver the asset. The seller hopes that the market price on the delivery date is less than the agreed upon price, while the buyer hopes for the contrary. The liquidity of the futures markets depends on participants entering into offsetting transactions rather than making or taking delivery. To the extent participants decide to make or take delivery, liquidity in the futures market could be reduced. In addition, futures exchanges often impose a maximum permissible price movement on each futures contract for each trading session. A Fund may be disadvantaged if it is prohibited from executing a trade outside

the daily permissible price movement. Moreover, to the extent a Fund engages in futures contracts on foreign exchanges, such exchanges may not provide the same protection as U.S. exchanges. The loss that a Fund may incur in entering into futures contracts may exceed the amount of the premium paid and may be potentially unlimited. Futures markets are highly volatile and the use of futures may increase the volatility of a Fund’s NAV. Additionally, as a result of the low collateral deposits normally involved in futures trading, a relatively small price movement in a futures contract may result in substantial losses for a Fund. Investments in these instruments involve risks, including counterparty risk (the risk that the counterparty to the instrument may not perform or be able to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains) and pricing risk (the risk that the instrument may be difficult to value), each of which may result in significant losses for a Fund.

Derivatives Risk/Interest Rate Swaps Risk. Interest rate swaps can be based on various measures of interest rates, including the London Interbank Offered Rate (commonly known as LIBOR), swap rates, treasury rates and other foreign interest rates. A swap agreement can increase or decrease the volatility of a Fund’s investments and its NAV. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for a Fund. Swaps can involve greater risks than direct investment in securities, because swaps may be leveraged, and are, among other factors, subject to counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument), hedging and correlation risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains, including because of a lack of correlation between the swaps and the portfolio of bonds that the swaps are designed to hedge or replace), pricing risk (swaps may be difficult to value), liquidity risk (it may not be possible to liquidate a swap position at an advantageous time or price) and interest rate risk (the risk of losses attributable to changes in interest rates), each of which may result in significant losses for a Fund.

Derivatives Risk/Inverse Floaters Risk. Inverse floaters (or inverse variable or floating rate securities) are a type of derivative, long-term fixed income obligation with a variable or floating interest rate that moves in the opposite direction of short-term interest rates. As short-term interest rates go down, the holders of the inverse floaters receive more income and, as short-term interest rates go up, the holders of the inverse floaters receive less income. Variable rate securities provide for a specified periodic adjustment in the interest rate, while floating rate securities have interest rates that change whenever there is a change in a designated benchmark rate or the issuer’s credit quality. While inverse floaters tend to provide more income than similar term and credit quality fixed-rate bonds, they also exhibit greater volatility in price movement. There is a risk that the current interest rate on variable and floating rate securities may not accurately reflect current market interest rates or adequately compensate the holder for the current creditworthiness of the issuer. Some variable or floating rate securities are structured with liquidity features and some may include market-dependent liquidity features that may present greater liquidity risk. Other risks associated with transactions in inverse floaters include interest rate risk (the risk of losses attributable to changes in interest rates), counterparty risk (the risk that the issuer of a security may or will default or otherwise become unable, or be perceived to be unable or unwilling, to honor a financial obligation, such as making payments when due) and hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), each of which may result in significant losses for a Fund.

Derivatives Risk/Options Risk. The use of options is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. If a Fund sells a put option, there is a risk that the Fund may be required to buy the underlying asset at a disadvantageous price. If a Fund sells a call option, there is a risk that the Fund may be required to sell the underlying asset at a disadvantageous price, and if the call option sold is not covered (for example, by owning the underlying asset), a Fund’s losses are potentially unlimited. Options may be traded on a securities exchange or in the over-the-counter market. These transactions involve other risks, including counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument) and hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), each of which may result in significant losses for a Fund.

Derivatives Risk/Swaps Risk. The use of swaps is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. In a swap transaction, one party agrees to pay the other party an amount equal to the return, based upon an agreed-upon notional value, of a defined underlying asset or a non-asset reference (such as an index) during a specified period of time. In return, the other party would make periodic payments based on a fixed or variable interest rate or on the return from a different underlying asset or non-asset reference based upon an agreed-upon notional value. Swaps could result in Fund losses if the underlying asset or reference does not perform as anticipated. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for a Fund. Such transactions can have the potential for unlimited losses. Such risk is heightened in the case of swap transactions involving short exposures. Swaps can involve greater risks than direct investment in the underlying asset, because swaps, among other factors, may be leveraged (creating leverage risk in that a Fund’s exposure and potential losses are greater than the amount invested) and are subject to counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), pricing risk (swaps may be difficult to value) and liquidity risk (it may not be possible to liquidate a swap position at an advantageous time or price), each of which may result in significant losses for a Fund.

Derivatives Risk/Portfolio Swaps and Total Return Swaps Risk. The use of portfolio swaps or total return swaps is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. In a swap transaction, one party agrees to pay the other party an amount equal to the total return of a defined underlying asset (such as an equity security or basket of such securities) or a non-asset reference (such as an index) during a specified period of time. In return, the other party would make periodic payments based on a fixed or variable interest rate or on the total return from a different underlying asset or non-asset reference. Portfolio swaps and equity swaps could result in losses if the underlying asset or reference does not perform as anticipated. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for a Fund. Such transactions can have the potential for unlimited losses. Such risk is heightened in the case of short swap transactions. Swaps can involve greater risks than direct investment in the underlying asset, because swaps, among other factors, may be leveraged (creating leverage risk) and are subject to counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset), pricing risk (swaps may be difficult to value) and liquidity risk ( it may not be possible to liquidate a swap position at an advantageous time or price), each of which may result in significant and unanticipated losses to a Fund.

Derivatives Risk/Total Return Swaps Risk. The use of total return swaps is a highly specialized activity which involves investment techniques and risks different from those associated with ordinary portfolio securities transactions. In a total return swap transaction, one party agrees to pay the other party an amount equal to the total return of a defined underlying asset (such as an equity security or basket of such securities) or a non-asset reference (such as an index) during a specified period of time. In return, the other party makes periodic payments based on a fixed or variable interest rate or on the total return from a different underlying asset or non-asset reference. Total return swaps could result in Fund losses if the underlying asset or reference does not perform as anticipated. Such transactions can have the potential for unlimited losses. The value of swaps, like many other derivatives, may move in unexpected ways and may result in losses for a Fund. Swaps can involve greater risks than direct investment in securities, because swaps, among other factors, may be leveraged (creating leverage risk in that a Fund’s exposure and potential losses are greater than the amount invested), and are subject to counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument), hedging risk (the risk that a hedging strategy may not eliminate the risk that it is intended to offset, and may offset gains), pricing risk (swaps may be difficult to value) and liquidity risk (the risk that it may not be possible for a Fund to liquidate a swap position at an advantageous time or price), which may result in significant losses for a Fund.

Derivatives Risk/Warrants Risk. Warrants are securities giving the holder the right, but not the obligation, to buy the stock of an issuer at a given price (generally higher than the value of the stock at the time of issuance) during a specified period or perpetually. Warrants may be acquired separately or in connection with the acquisition of securities. Warrants do not carry with them the right to dividends or voting rights and they do not represent any rights in the assets of the issuer. In addition, the value of a warrant does not necessarily change with the value of the underlying securities, and a warrant ceases to have value if it is not exercised prior to its expiration date. Warrants 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. Investment in these instruments also subject a Fund to liquidity risk (the risk that it may not be possible for a Fund to liquidate the instrument at an advantageous time or price), which may result in significant losses for a Fund.

Dollar rolls are transactions in which a Fund or a Portfolio Fund sells securities to a counterparty and simultaneously agrees to purchase those or similar securities in the future at a predetermined price. Dollar rolls involve the risk that the market value of the securities a Fund or a Portfolio Fund is obligated to repurchase may decline below the repurchase price, or that the counterparty may default on its obligations. These transactions may also increase a Fund’s portfolio turnover rate. If a Fund or a Portfolio Fund reinvests the proceeds of the security sold, the Fund or the Portfolio Fund will also be subject to the risk that the investments purchased with such proceeds will decline in value (a form of leverage risk).

Securities issued by foreign governments or companies in emerging market countries, such as China, Russia and certain countries 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 changes or developments in social, political, economic or other conditions. Their economies are usually less mature and their securities markets are typically less developed with more limited trading activity (i.e., lower trading volumes and less liquidity) 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 and have fewer trading partners, which makes them more sensitive to world commodity prices and economic downturns in other countries. Some emerging market countries have a higher risk of currency devaluations, and some of these countries may experience periods of high inflation or rapid changes in inflation rates and may have hostile relations with 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 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.

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 China and Russia.

China Stock Connect Risk. The risks noted here are in addition to the risks described under Emerging Market Securities Risk. A Fund or a Portfolio Fund may purchase shares in mainland China-based companies that trade on Chinese stock exchanges such as the Shanghai Stock Exchange and the Shenzhen Stock Exchange (China A-Shares) through the Shanghai-Hong Kong Stock Connect (Stock Connect), a mutual market access program designed to, among other things, enable foreign investment in the People’s Republic of China (PRC) via brokers in Hong Kong. There are significant risks inherent in investing in China A-Shares through Stock Connect. The underdeveloped state of PRC’s investment and banking systems subjects the settlement, clearing, and registration of China A-Shares transactions to heightened risks. Stock Connect can only operate when both PRC and Hong Kong markets are open for trading and when banking services are available in both markets on the corresponding settlement days. As such, if either or both markets are closed on a U.S. trading day, a Fund or a Portfolio Fund may not be able to dispose of its China A-Shares in a timely manner, which could adversely affect a Fund’s or a Portfolio Fund’s performance. PRC regulations require that a fund that wishes to sell its China A-Shares pre-deliver the China A-Shares to a broker. If the China A-Shares are not in the broker’s possession before the market opens on the day of sale, the sell order will be rejected. This requirement could also limit a Fund’s or a Portfolio Fund’s ability to dispose of its China A-Shares purchased through Stock Connect in a timely manner. Additionally, Stock Connect is subject to daily quota limitations on purchases of China A-Shares. Once the daily quota is reached, orders to purchase additional China A-Shares through Stock Connect will be rejected. A Fund’s or a Portfolio Fund’s investment in China A-Shares may only be traded through Stock Connect and is not otherwise transferable. Stock Connect utilizes an omnibus clearing structure, and a Fund’s or a Portfolio Fund’s shares will be registered in its custodian’s name on the Central Clearing and Settlement System. This may limit the ability of the Investment Manager or the ability of a Portfolio Fund’s investment adviser (and/or any sub-adviser, as the case may be) to effectively manage a Fund or a Portfolio Fund, and may expose a Fund or a Portfolio Fund to the credit risk of its custodian or to greater risk of expropriation. Investment in China A-Shares through Stock Connect may be available only through a single broker that is an affiliate of a Fund’s or a Portfolio Fund’s custodian or foreign sub-custodian, which may affect the quality of execution provided by such broker. Stock Connect restrictions could also limit the ability of a Fund or a Portfolio Fund to sell its China A-Shares in a timely manner, or to sell them at all. Further, different fees, costs and taxes are imposed on foreign investors acquiring China A-Shares acquired through Stock Connect, and these fees, costs and taxes may be higher than comparable fees, costs and taxes imposed on owners of other securities providing similar investment exposure.

A number of countries in the European Union (EU) have experienced, and may continue to experience, severe economic and financial difficulties. Additional EU member countries may also fall subject to such difficulties. These events could negatively affect the value and liquidity of a Fund’s investments in euro-denominated securities and derivatives contracts, securities of issuers located in the EU or with significant exposure to EU issuers or countries. If the euro is dissolved entirely, the legal and contractual consequences for holders of euro-denominated obligations and derivative contracts would be determined by laws in effect at such time. Such investments may continue to be held, or purchased, to the extent consistent with a Fund’s investment

objective and permitted under applicable law. These potential developments, or market perceptions concerning these and related issues, could adversely affect the value of Fund shares.

Certain countries in the EU have had to accept assistance from supra-governmental agencies such as the International Monetary Fund, the European Stability Mechanism (the ESM) or other supra-governmental agencies. The European Central Bank has also been intervening to purchase Eurozone debt in an attempt to stabilize markets and reduce borrowing costs.

There can be no assurance that these agencies will continue to intervene or provide further assistance and markets may react adversely to any expected reduction in the financial support provided by these agencies. Responses to the financial problems by European governments, central banks and others including austerity measures and reforms, may not work, may result in social unrest and may limit future growth and economic recovery or have other unintended consequences. In addition, one or more countries may abandon the euro and/or withdraw from the EU. The impact of these actions, especially if they occur in a disorderly fashion, could be significant and far-reaching.

A Fund may seek to profit from the occurrence of specific corporate or other events. A delay in the timing of these events, or the failure of these events to occur at all, may have a significant negative effect on a Fund’s performance.

Event-driven investing requires a Fund’s portfolio manager to make predictions about (i) the likelihood that an event will occur and (ii) the impact such event will have on the value of a company’s securities. If the event fails to occur or it does not have the effect foreseen, losses can result. For example, the adoption of new business strategies, a meaningful change in management or the sale of a division or other significant assets by a company may not be valued as highly by the market as the portfolio manager had anticipated, resulting in losses. In addition, a company may announce a plan of restructuring which promises to enhance value and fail to implement it, resulting in losses to investors.

An ETF’s share price may not track its specified market index (if any) and may trade below its net asset value. Certain ETFs use a “passive” investment strategy and do not take defensive positions in volatile or declining markets. Other ETFs in which a Fund may invest are actively managed ETFs (i.e., they do not track a particular benchmark), which indirectly subjects a Fund to active management risk. An active secondary market in an ETF’s shares may not develop or be maintained and may be halted or interrupted due to actions by its listing exchange, unusual market conditions or other reasons. There can be no assurance an ETF’s shares will continue to be listed on an active exchange. In addition, shareholders bear both their proportionate share of a Fund’s expenses and similar expenses incurred through ownership of the ETF.

Each Fund generally expects to purchase shares of ETFs through broker-dealers in transactions on a securities exchange, and in such cases a Fund will pay customary brokerage commissions for each purchase and sale. Shares of an ETF may also be acquired by depositing a specified portfolio of the ETF’s underlying securities, as well as a cash payment generally equal to accumulated dividends of the securities (net of expenses) up to the time of deposit, with the ETF’s custodian, in exchange for which the ETF will issue a quantity of new shares sometimes referred to as a “creation unit”. Similarly, shares of an ETF purchased on an exchange may be accumulated until they represent a creation unit, and the creation unit may be redeemed in kind for a portfolio of the underlying securities (based on the ETF’s net asset value) together with a cash payment generally equal to accumulated dividends as of the date of redemption. A Fund may redeem creation units for the underlying securities (and any applicable cash), and may assemble a portfolio of the underlying securities (and any required cash) to purchase creation units. Each Fund’s ability to redeem creation units may be limited by the 1940 Act,

which provides that ETFs, the shares of which are purchased in reliance on Section 12(d)(1)(F) of the 1940 Act, will not be obligated to redeem such shares in an amount exceeding one percent of their total outstanding securities during any period of less than 30 days.

The performance of a Fund may be materially affected positively or negatively by foreign currency strength or weakness relative to the U.S. dollar, particularly if the Fund invests a significant percentage of its assets in foreign securities or other assets denominated in currencies other than the U.S. dollar. Currency rates in foreign countries may fluctuate significantly over short or long periods of time for a number of reasons, including changes in interest rates, imposition of currency controls and economic or political developments in the U.S. or abroad. A Fund may also incur currency conversion costs when converting foreign currencies into U.S. dollars and vice versa.

Investments in or exposure to foreign securities involve certain risks not associated with investments in or exposure to securities of U.S. companies. For example, foreign markets can be extremely volatile. The performance of a Fund may be negatively impacted by fluctuations in a foreign currency’s strength or weakness relative to the U.S. dollar. Foreign securities may also be less liquid than securities of U.S. companies so that a Fund may, at times, be unable to sell foreign securities at desirable times or prices. Brokerage commissions, custodial costs and other fees are also generally higher for foreign securities. A 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. In addition, foreign governments may impose potentially confiscatory withholding or other taxes on a Fund’s income, capital gains or proceeds from the disposition of foreign securities, which could reduce the Fund’s return on such securities. Other risks include: possible delays in the settlement of transactions or in the payment of income; generally less publicly available information about foreign companies; the impact of economic, political, social, diplomatic or other conditions or events; possible seizure, expropriation or nationalization of a company or its assets or the assets of a particular investor or category of investors; possible imposition of currency exchange controls; accounting, auditing and financial reporting standards that may be less comprehensive and stringent than those applicable to domestic companies; the imposition of economic and other sanctions against a particular foreign country, its nationals or industries or businesses within the country; and the generally less stringent standard of care to which local agents may be held in the local markets. In addition, it may be difficult to obtain reliable information about the securities and business operations of certain foreign issuers. Governments or trade groups may compel local agents to hold securities in designated depositories that are not subject to independent evaluation. The less developed a country’s securities market is, the greater the level of risks. The risks posed by sanctions against a particular foreign country, its nationals or industries or businesses within the country may be heightened to the extent a Fund invests significantly in the affected country or region or in issuers from the affected country that depend on global markets.

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 (“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 a Fund. In particular, under certain circumstances, foreign securities may settle on a delayed delivery basis, meaning that a 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, a 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.

Forward Commitments on Mortgage-Backed Securities (including Dollar Rolls) Risk

When purchasing mortgage-backed securities in the “to be announced” (TBA) market (MBS TBAs), the seller agrees to deliver mortgage-backed securities for an agreed upon price on an agreed upon date, but may make no guarantee as to the specific securities to be delivered. In lieu of taking delivery of mortgage-backed securities, a Fund or a Portfolio Fund could enter into dollar rolls, which are transactions in which the Fund or the Portfolio Funds sells securities to a counterparty and simultaneously agrees to purchase those or similar securities in the future at a predetermined price. Dollar rolls involve the risk that the market value of the securities a Fund or a Portfolio Fund is obligated to repurchase may decline below the repurchase price, or that the counterparty may default on its obligations. These transactions may also increase a Fund’s or a Portfolio Fund’s portfolio turnover rate. If a Fund or a Portfolio Fund reinvests the proceeds of the security sold, the Fund or the Portfolio Fund will also be subject to the risk that the investments purchased with such proceeds will decline in value (a form of leverage risk). MBS TBAs and dollar rolls are subject to counterparty risk (the risk that the counterparty to the instrument will not perform or be able to perform in accordance with the terms of the instrument).

Frontier market countries generally have smaller economies and even less developed capital markets than typical emerging market countries (which themselves have increased investment risk relative to more developed market countries) and, as a result, a Fund’s exposure to risks associated with investing in emerging market countries are magnified when a Fund invests in frontier market countries. The increased risks include: the potential for extreme price volatility and illiquidity in frontier market countries; government ownership or control of parts of the 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. Securities issued by foreign governments or companies in frontier market countries are even more likely than emerging markets securities to have greater exposure to the risks of investing in foreign securities that are described in Foreign Securities Risk.

Determinations regarding asset classes or Portfolio Funds and a Fund’s allocations thereto may not successfully achieve a Fund’s investment objective, in whole or in part. The selected Portfolio Funds’ performance may be lower than the performance of the asset class they were selected to represent or may be lower than the performance of alternative Portfolio Funds that could have been selected to represent the asset class. A Fund also is exposed to the same risks as the Portfolio Funds in direct proportion to the allocation of its assets among the Portfolio Funds. By investing in a combination of Portfolio Funds, a Fund has exposure to the risks of many areas of the market. The ability of a Fund to realize its investment objective will depend, in large

part, on the extent to which the Portfolio Funds realize their investment objectives. There is no guarantee that the Portfolio Funds will achieve their respective investment objectives. The performance of Portfolio Funds could be adversely affected if other entities that invest in the same Portfolio Funds make relatively large investments or redemptions in such Portfolio Funds. A Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of each Portfolio Fund are shared by its investors, redemptions by other investors in a Portfolio Fund could result in decreased economies of scale and increased operating expenses for such fund. These transactions might also result in higher brokerage, tax or other costs for a Portfolio Fund. This risk may be particularly important when one investor owns a substantial portion of a Portfolio Fund. The Investment Manager may have potential conflicts of interest in selecting affiliated funds over unaffiliated funds for investment by a Fund, and may also face potential conflicts of interest in selecting affiliated funds, because the fees the Investment Manager and its affiliates, including the investment adviser to the Portfolio Funds, receive from some Portfolio Funds may be higher than the fees paid by other Portfolio Funds. Further, because of the Investment Manager’s confidence in its own strategies, investment philosophy and capacities, it will, in selecting funds, at times prefer Columbia Acorn Funds over alternative investments. There can be no assurance, however, that an Acorn Fund selected for inclusion in Columbia Thermostat Fund will, in fact, outperform similar funds managed by the Investment Manager’s affiliates.

A Fund may be particularly susceptible to economic, political, regulatory or other events or conditions affecting issuers and countries within the specific geographic regions in which the Fund invests. Currency devaluations could occur in countries that have not yet experienced currency devaluation to date, or could continue to occur in countries that have already experienced such devaluations. As a result, a Fund’s NAV may be more volatile than the NAV of a more geographically diversified fund.

Growth securities typically trade at a higher multiple of earnings than other types of equity securities. Accordingly, the market values of growth securities may never reach their expected market value and may decline in price. 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.

Securities rated below investment grade (commonly called “high yield” or “junk” bonds) and unrated securities of comparable quality tend to be more sensitive to credit risk than higher-rated securities and may experience greater price fluctuations in response to perceived changes in the ability of the issuing entity or obligor to pay interest and principal when due than to changes in interest rates. These investments are generally more likely to experience a default than higher-rated securities. High yield securities are considered to be predominantly speculative with respect to the issuer’s capacity to pay interest and repay principal. These securities typically pay a premium — a higher interest rate or yield — because of the increased risk of loss, including default. High yield securities may require a greater degree of judgment to establish a price, may be difficult to sell at the time and price a Fund desires, may carry high transaction costs, and also are generally less liquid than higher-rated securities. The securities ratings provided by third party rating agencies 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. In adverse economic and other circumstances, issuers of lower-rated securities are more likely to have difficulty making principal and interest payments than issuers of higher-rated securities.

The loans or other securities in which a Fund invests may consist of transactions involving refinancings, recapitalizations, mergers and acquisitions and other financings for general corporate purposes. A Fund’s investments also may include senior obligations of a borrower issued in connection with a restructuring pursuant to Chapter 11 of the U.S. Bankruptcy Code (commonly known as “debtor-in-possession” financings), provided that such senior obligations are determined by the Investment Manager or the investment adviser to a Portfolio Fund to be a suitable investment for the Fund. In such highly leveraged transactions, the borrower assumes large amounts of debt in order to have the financial resources to attempt to achieve its business objectives. Such business objectives may include but are not limited to: management’s taking over control of a company (leveraged buy-out); reorganizing the assets and liabilities of a company (leveraged recapitalization); or acquiring another company. Loans or securities that are part of highly leveraged transactions involve a greater risk (including default and bankruptcy) than other investments.

The value of collateral, if any, securing a loan can decline, and may be insufficient to meet the borrower’s obligations or difficult or costly to liquidate. In addition, a Fund’s access to collateral may be limited by bankruptcy or other insolvency laws. Further, certain floating rate and other loans may not be fully collateralized and may decline in value.

Inflation risk is the uncertainty over the future real value (after inflation) of an investment. Inflation rates may change frequently and drastically as a result of various factors, including unexpected shifts in the domestic or global economy, and a Fund’s investments may not keep pace with inflation, which may result in losses to Fund investors.

Inflation-protected debt securities tend to react to changes in real interest rates. Real interest rates can be described as nominal interest rates minus the expected impact of inflation. In general, the price of an inflation-protected debt security falls when real interest rates rise, and rises when real interest rates fall. Interest payments on inflation-protected debt securities will vary as the principal and/or interest is adjusted for inflation and may be more volatile than interest paid on ordinary bonds. In periods of deflation, a Fund may have no income at all from such investments. Income earned by a shareholder depends on the amount of principal invested, and that principal will not grow with inflation unless the shareholder reinvests the portion of Fund distributions that comes from inflation adjustments. A Fund’s investment in certain inflation-protected debt securities may generate taxable income in excess of the interest they pay to the Fund, which may cause the Fund to sell investments to obtain cash to make income distributions to shareholders, including at times when it may not be advantageous to do so.

IPOs are subject to many of the same risks as investing in companies with smaller market capitalizations. To the extent a Fund determines to invest in IPOs, it may not be able to invest to the extent desired, because, for example, only a small portion (if any) of the securities being offered in an IPO are available to a Fund. The investment performance of a Fund during periods when it is unable to invest significantly or at all in IPOs may be lower than during periods when the Fund is able to do so. In addition, as a Fund increases in size, the impact of IPOs on the Fund’s performance will generally decrease. IPOs sold within 12 months of purchase may result in increased short-term capital gains, which will be taxable to a Fund’s shareholders as ordinary income.

Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt securities tend to fall, and if interest rates fall, the values of debt securities tend to rise. Changes in the value of a debt security usually will not affect the amount of income a Fund receives from it but will usually affect the value of the Fund’s shares. In general, the longer the maturity or duration of a debt security, the greater its sensitivity to changes in interest rates. Interest rate declines also may increase prepayments of debt obligations, which, in turn, would increase prepayment risk. Similarly, a period of rising interest rates may negatively impact a Fund’s performance. Actions by governments and central banking authorities can result in increases in interest rates. Such actions may negatively affect the value of fixed-income securities held by a Fund, resulting in a negative impact on the Fund’s performance and NAV. Securities with floating coupon rates are typically less sensitive to interest rate changes, but these securities may decline in value if their coupon rates do not rise as much as, or keep pace with, yields on such types of securities. Because rates on certain floating rate loans and other debt securities reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause fluctuations in a Fund’s NAV.

A Fund’s investment in other funds (affiliated and/or unaffiliated funds, including exchange-traded funds (ETFs)) subjects the Fund to the investment performance (positive or negative) and risks of the Portfolio Funds or other underlying funds in direct proportion to the Fund’s investment therein. In addition, investments in ETFs have unique characteristics, including, but not limited to, the expense structure and additional expenses associated with investing in ETFs. The performance of the Portfolio Funds or other underlying funds could be adversely affected if other investors in the same Portfolio Funds or other underlying funds make relatively large investments or redemptions in such Portfolio Funds or other underlying funds. A Fund, and its shareholders, indirectly bear a portion of the expenses of any funds in which the Fund invests. Because the expenses and costs of a fund are shared by its investors, redemptions by other investors in the Portfolio Funds or other underlying funds could result in decreased economies of scale and increased operating expenses for such fund. These transactions might also result in higher brokerage, tax or other costs for the Portfolio Funds or other underlying funds. This risk may be particularly important when one investor owns a substantial portion of the Portfolio Funds or other underlying funds. The Investment Manager may have potential conflicts of interest in selecting affiliated Portfolio Funds or other underlying funds for investment by a Fund because the fees paid to it or its affiliates, including the investment adviser to the Portfolio Funds, by some Portfolio Funds or other underlying funds are higher than the fees paid by other Portfolio Funds or other underlying funds, as well as a potential conflict in selecting affiliated funds over unaffiliated funds. Also, to the extent that a Fund is constrained/restricted from investing (or investing further) in a particular Portfolio Fund or other underlying fund for one or more reasons (e.g., Portfolio Fund or other underlying fund capacity constraints or regulatory restrictions) or if a Fund chooses to sell its investment in a Portfolio Fund or other underlying fund because of poor investment performance or for other reasons, the Fund may have to invest in one or more other Portfolio Funds or other underlying funds, including less desirable funds — from a strategy or investment performance standpoint — which could have a negative impact on Fund performance. In addition, Fund performance could be negatively impacted if one or more appropriate alternate Portfolio Funds or other underlying funds are not identified or available for investment timely or at all.

An issuer in which a Fund invests or to which it has exposure may perform poorly, and the value of its securities may therefore decline, which would negatively affect the Fund’s performance. Poor performance may be caused by poor management decisions, competitive pressures, breakthroughs in technology, reliance on suppliers, labor problems or shortages, corporate restructurings, fraudulent disclosures, natural disasters or other events, conditions or factors.

Leverage occurs when a Fund increases its assets available for investment using borrowings, short sales, derivatives, or similar instruments or techniques. If a fund uses leverage, through purchasing particular instruments such as derivatives, a Fund has the risk of capital losses that exceed its net assets. Because short sales involve borrowing securities and then selling them, a Fund’s short sales effectively leverage the Fund’s assets. A Fund’s assets that are used as collateral to secure the Fund’s obligations to return the securities sold short may decrease in value while the short positions are outstanding, which may force the Fund to use its other assets to increase the collateral. Leverage can create an interest expense that may lower a Fund’s overall returns. Leverage presents the opportunity for increased net income and capital gains, but may also exaggerate a Fund’s volatility and risk of loss. There can be no guarantee that a leveraging strategy will be successful.

Liquidity risk is the risk associated with a lack of marketability of investments which may make it difficult to sell the investment at a desirable time or price. Decreases in the number of financial institutions willing to make markets in a Fund’s investments or in their capacity or willingness to trade such investments may increase the Fund’s exposure to this risk. Changing regulatory, market or other conditions or environments (for example, the interest rate or credit environments) may also adversely affect the liquidity of a Fund’s investments. A Fund may have to accept a lower selling price for the holding, sell other investments, or forego another, more appealing investment opportunity. Judgment plays a larger role in valuing these investments as compared to valuing more liquid investments. Price volatility may be higher for illiquid investments as a result of, for example, the relatively less frequent pricing of such securities (as compared to liquid investments). Generally, the less liquid the market at the time a Fund sells a portfolio investment, the greater the risk of loss or decline of value to the Fund. Price volatility, liquidity of the market and other factors can lead to an increase in Fund redemptions, which may negatively impact Fund performance and NAV, including, for example, if a Fund is forced to sell securities in a down market. For more information on the liquidity and trading volume risks associated with investing in the international Funds in the Columbia Acorn Family of Funds, see Permissible Fund Investments — Foreign Securities — Liquidity and Trading Volume Risks of Foreign Investing.

Private equity funds include financial institutions or vehicles whose principal business is to invest in and lend capital to privately held companies. A Fund is subject to the underlying risks that affect private equity funds in which it invests, which may include increased liquidity risk, valuation risk, sector risk and credit risk. Limited or incomplete information about the companies in which private equity funds invest, and relatively concentrated investment portfolios of private equity funds, may expose a Fund to greater volatility and risk of loss. A Fund’s investment in private equity funds subjects Fund shareholders indirectly to the fees and expenses incurred by private equity funds.

The profitability of any macro program depends primarily on the ability of its manager to predict derivative contract price movements to implement investment theses regarding macroeconomic trends. Price movements for commodity interests are influenced by, among other things: changes in interest rates; governmental, agricultural, trade, fiscal, monetary and exchange control programs and policies; weather and climate conditions; natural disasters, such as hurricanes; changing supply and demand relationships; changes in balances of payments and trade; U.S. and international rates of inflation and deflation; currency devaluations and revaluations; U.S. and international political and economic events; and changes in philosophies and emotions of market participants. The manager’s trading methods may not take all of these factors into account.

The global macro programs to which a Fund’s investments are exposed typically use derivative financial instruments that are actively traded using a variety of strategies and investment techniques that involve

significant risks. The derivative financial instruments traded include commodities, currencies, futures, options and forward contracts and other derivative instruments that have inherent leverage and price volatility that result in greater risk than instruments used by typical mutual funds, and the systematic programs used to trade them may rely on proprietary investment strategies that are not fully disclosed, which may in turn result in risks that are not anticipated.

Market risk refers to the possibility that the market values of securities or other investments that a Fund holds will fall, sometimes rapidly or unpredictably, or fail to rise. Security values may fall or fail to rise because of a variety of actual or perceived factors affecting an issuer (e.g., an unfavorable earnings report), the industry or sector in which it operates, or the market as a whole, which may reduce the value of an investment in a Fund. Accordingly, an investment in a Fund could lose money over short or long periods. The market values of the securities a Fund holds 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. Although equity securities generally tend to have greater price volatility than debt securities, under certain market conditions, debt securities may have comparable or greater price volatility. In addition, stock prices may be sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase.

Investments in securities (units) of master limited partnerships involve risks that differ from an investment in common stock. Holders of these units have more limited rights to vote on matters affecting the partnership. These units may be subject to cash flow and dilution risks. There are also certain tax risks associated with such an investment. In particular, a Fund’s investment in master limited partnerships can be limited by the Fund’s intention to qualify as a regulated investment company for U.S. federal income tax purposes, and can limit the Fund’s ability to so qualify. In addition, conflicts of interest may exist between common unit holders, subordinated unit holders and the general partner of a master limited partnership, including a conflict arising as a result of incentive distribution payments. In addition, there are risks related to the general partner’s right to require unit holders to sell their common units at an undesirable time or price.

Securities of mid-capitalization companies (mid-cap companies) can, in certain circumstances, have more risk than securities of larger capitalization companies (larger companies). For example, mid-cap companies may be more vulnerable to market downturns and adverse business or economic events than larger companies because they may have more limited financial resources and business operations. Mid-cap companies are also more likely than larger companies to have more limited product lines and operating histories and to depend on smaller management teams. Securities of mid-cap companies may trade less frequently and in smaller volumes and may fluctuate more sharply in value than securities of larger companies. When a Fund takes significant positions in mid-cap companies with limited trading volumes, the liquidation of those positions, particularly in a distressed market, could be difficult and result in Fund investment losses. In addition, some mid-cap companies may not be widely followed by the investment community, which can lower the demand for their stocks.

An investment in a money market fund is not a bank deposit and is not insured or guaranteed by any bank, the FDIC or any other government agency. Although money market funds seek to preserve the value of investments at $1.00 per share, it is possible for a Fund to lose money by investing in money market funds. In addition to the fees and expenses that a Fund directly bears, the Fund indirectly bears the fees and expenses of any money market funds in which it invests, including affiliated money market funds. To the extent these fees and expenses, along with the fees and expenses of any other funds in which a Fund may invest, are expected to equal or exceed 0.01% of the Fund’s average daily net assets, they will be reflected in the Annual Fund

Operating Expenses set forth in the table under “Fees and Expenses of the Fund.” By investing in a money market fund, a Fund will be exposed to the investment risks of the money market fund in direct proportion to such investment. The money market fund may not achieve its investment objective. A Fund, through its investment in the money market fund, may not achieve its investment objective. To the extent a Fund invests in instruments such as derivatives, the Fund may hold investments, which may be significant, in money market fund shares to cover its obligations resulting from the Fund’s investments in derivatives. Money market funds and the securities they invest in are subject to comprehensive regulations. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operation, performance and/or yield of money market funds.

The value of any mortgage-backed and other asset-backed securities held by a Fund or a Portfolio Fund may be affected by, among other things, changes or perceived changes in: interest rates; factors concerning the interests in and structure of the issuer or the originator of the mortgages or other assets; the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements; or the market’s assessment of the quality of underlying assets. Mortgage-backed securities represent interests in, or are backed by, pools of mortgages from which payments of interest and principal (net of fees paid to the issuer or guarantor of the securities) are distributed to the holders of the mortgage-backed securities. Other types of asset-backed securities typically represent interests in, or are backed by, pools of receivables such as credit, automobile, student and home equity loans. Mortgage- and other asset-backed securities can have a fixed or an adjustable rate. Mortgage- and other asset-backed securities are subject to prepayment risk, which is the possibility that the underlying mortgage or other asset may be refinanced or prepaid prior to maturity during periods of declining or low interest rates, causing a Fund or a Portfolio Fund to have to reinvest the money received in securities that have lower yields. In addition, the impact of prepayments on the value of mortgage- and other asset-backed securities may be difficult to predict and may result in greater volatility. Rising or high interest rates tend to extend the duration of mortgage- and other asset-backed securities, making them more volatile and more sensitive to changes in interest rates. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed (i) by the full faith and credit of the U.S. Government (in the case of securities guaranteed by the Government National Mortgage Association) or (ii) by its agencies, authorities, enterprises or instrumentalities (in the case of securities guaranteed by the Federal National Mortgage Association (FNMA) or the Federal Home Loan Mortgage Corporation (FHLMC)), which are not insured or guaranteed by the U.S. Government (although FNMA and FHLMC may be able to access capital from the U.S. Treasury to meet their obligations under such securities). Mortgage-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may be supported by various credit enhancements, such as pool insurance, guarantees issued by governmental entities, letters of credit from a bank or senior/subordinated structures, and may entail greater risk than obligations guaranteed by the U.S. Government, whether or not such obligations are guaranteed by the private issuer.

Municipal securities are debt obligations generally issued to obtain funds for various public purposes, including general financing for state and local governments, or financing for a specific project or public facility, and include obligations of the governments of the U.S. territories, commonwealths and possessions such as Puerto Rico, the Virgin Islands, Guam and the Northern Mariana Islands to the extent such obligations are exempt from state and federal income taxes. Municipal securities can be significantly affected by political and legislative changes at the state or federal level. Municipal securities may be fully or partially backed by the taxing authority of the local government, by the credit of a private issuer, by the current or anticipated revenues from a specific project or specific assets or by domestic or foreign entities providing credit support, such as letters of credit, guarantees or insurance, and are generally classified into general obligation bonds and special revenue obligations. General obligation bonds are backed by an issuer’s taxing authority and may be vulnerable to limits on a government’s

power or ability to raise revenue or increase taxes. They may also depend for payment on legislative appropriation and/or funding or other support from other governmental bodies. Revenue obligations are payable from revenues generated by a particular project or other revenue source, and are typically subject to greater risk of default than general obligation bonds because investors can look only to the revenue generated by the project or other revenue source backing the project, rather than to the general taxing authority of the state or local government issuer of the obligations. Because many municipal securities are issued to finance projects in sectors such as education, health care, transportation and utilities, conditions in those sectors can affect the overall municipal market. Municipal securities generally pay interest that, in the opinion of bond counsel, is free from U.S. federal income tax (and, in some cases, the federal alternative minimum tax). There is no assurance that the Internal Revenue Service (IRS) will agree with this opinion or that U.S. federal income tax law will not change. In the event the IRS determines that the issuer does not comply with relevant tax requirements or U.S. federal income tax law changes, interest payments from a security could become federally taxable, possibly retroactively to the date the security was issued, and the value of the security would likely fall. As a shareholder of a Fund, you may be required to file an amended tax return and pay additional taxes as a result. The amount of publicly available information for municipal issuers is generally less than for corporate issuers.

Certain of the municipalities or territories in which a Fund or a Portfolio Fund may invest have recently experienced significant financial difficulties. A credit rating downgrade relating to, default by, or insolvency or bankruptcy of, one or several municipal security issuers of a state, territory, commonwealth or possession in which a Fund or a Portfolio Fund invests could affect the market values and marketability of many or all municipal obligations of such state, territory, commonwealth or possession.

A Fund’s or a Portfolio Fund’s investments in municipal securities may include securities of issuers in the health care sector, which subjects the Fund’s or the Portfolio Fund’s investments to the risks associated with that sector, including the risk of regulatory action or policy changes by numerous governmental agencies and bodies, including federal, state, and local governmental agencies, as well as requirements imposed by private entities, such as insurance companies. A major source of revenue for the health care industry is payments from the Medicare and Medicaid programs. As a result, the industry is sensitive to legislative changes and reductions in governmental spending for such programs. Numerous other factors may affect the industry, such as general and local economic conditions, demand for services, expenses (including, among others, malpractice insurance premiums) and competition among health care providers. Additional factors also may adversely affect health care facility operations, such as adoption of legislation proposing a national health insurance program, other state or local health care reform measures, medical and technological advances that alter the need for or cost of health services or the way in which such services are delivered, changes in medical coverage that alter the traditional fee-for-service revenue stream, and efforts by employers, insurers, and governmental agencies to reduce the costs of health insurance and health care services.

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.

Prepayment risk is the risk that a loan, bond or other security or investment might be called or otherwise converted, prepaid or redeemed before maturity, and extension risk is the risk that the investment might not be called as expected. In the case of prepayment risk, if the investment is converted, prepaid or redeemed before maturity, particularly during a time of declining interest rates or spreads, the Investment Manager or the

investment adviser to a Portfolio Fund may not be able to invest the proceeds in other investments providing as high a level of income, resulting in a reduced yield to a Fund. Conversely, in the case of extension risk, as interest rates rise or spreads widen, the likelihood of prepayment decreases and the maturity of the investment may extend the life of the investment beyond the prepayment time. If a Fund’s investments are locked in at a lower interest rate for a longer period of time, the Investment Manager or the investment adviser to a Portfolio Fund may be unable to capitalize on securities with higher interest rates or wider spreads.

Investments in real estate investment trusts (REITs) and in securities of other companies (wherever organized) principally engaged in the real estate industry subject a Fund to, among other things, risks similar to those of direct investments in real estate and the real estate industry in general. These include risks related to general and local economic conditions, possible lack of availability of financing and changes in interest rates or property values. REITs are entities that either own properties or make construction or mortgage loans, and also may include operating or finance companies. The value of interests in a REIT may be affected by, among other factors, changes in the value of the underlying properties owned by the REIT, changes in the prospect for earnings and/or cash flow growth of the REIT itself, defaults by borrowers or tenants, market saturation, decreases in market rates for rents, and other economic, political, or regulatory matters affecting the real estate industry, including REITs. REITs and similar non-U.S. entities depend upon specialized management skills, may have limited financial resources, may have less trading volume in their securities, and may be subject to more abrupt or erratic price movements than the overall securities markets. REITs are also subject to the risk of failing to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended. Some REITs (especially mortgage REITs) are affected by risks similar to those associated with investments in debt securities including changes in interest rates and the quality of credit extended.

A Fund may need to sell portfolio securities to meet redemption requests. A Fund could experience a loss when selling portfolio securities to meet redemption requests if there is (i) significant redemption activity by shareholders, including, for example, when a single investor or few large investors make a significant redemption of Fund shares, (ii) a disruption in the normal operation of the markets in which a Fund buys and sells portfolio securities or (iii) the inability of a Fund to sell portfolio securities because such securities are illiquid. In such events, a Fund could be forced to sell portfolio securities at unfavorable prices in an effort to generate sufficient cash to pay redeeming shareholders. A Fund may suspend redemptions or the payment of redemption proceeds when permitted by applicable regulations.

Money market funds and the securities they invest in are subject to comprehensive regulations. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operation, performance and/or yield of money market funds. For example, in July 2014 the SEC adopted amendments to money market regulation designed to address, among other things, systemic risks associated with money market funds and to enhance transparency for money market fund investors. These rules provide for liquidity fees or redemption gates for non-government money market funds if portfolio liquidity drops below specified levels and will require institutional prime money market funds to price shares with a floating net asset value. These rule changes may impact the future operations, performance and/or yields of the Columbia money market funds and other money market funds. Non-governmental money market funds will be required to restrict beneficial owners to natural persons if they want to maintain a stable net asset value. Because government money market funds will not be required to float their net asset value or impose liquidity fees or redemption gates, money market funds may decide to change investment strategies to qualify as government money market funds. Money market funds are required to comply with the liquidity fees, redemption gates and floating net asset value rules by October 2016 and most of the other rules by April 2016.

Reinvestment risk is the risk that a Fund will not be able to reinvest income or principal at the same return it is currently earning.

Repurchase agreements are agreements in which the seller of a security to a Fund agrees to repurchase that security from the Fund at a mutually agreed upon price and time. Repurchase agreements carry the risk that the counterparty may not fulfill its obligations under the agreement. This could cause a Fund’s income and the value of your investment in the Fund to decline.

Reverse repurchase agreements are agreements in which a Fund sells a security to a counterparty, such as a bank or broker-dealer, in return for cash and agrees to repurchase that security at a mutually agreed upon price and time. Reverse repurchase agreements carry the risk that the market value of the security sold by a Fund may decline below the price at which the Fund must repurchase the security. Reverse repurchase agreements also may be viewed as a form of borrowing, and borrowed assets used for investment creates leverage risk. Leverage can create an interest expense that may lower a Fund’s overall returns. Leverage presents the opportunity for increased net income and capital gains, but may also exaggerate a Fund’s volatility and risk of loss. There can be no guarantee that this strategy will be successful.

A Fund may invest in privately placed “Rule 144A” securities that are determined to be liquid in accordance with procedures adopted by the Board. However, an insufficient number of qualified institutional buyers interested in purchasing Rule 144A securities at a particular time could affect adversely the marketability of such securities and a Fund might be unable to dispose of such securities promptly or at reasonable prices. Accordingly, even if determined to be liquid, a Fund’s holdings of Rule 144A securities may increase the level of Fund illiquidity if eligible buyers become uninterested in buying them at a particular time. A Fund may also have to bear the expense of registering the securities for resale and the risk of substantial delays in effecting the registration. Additionally, the purchase price and subsequent valuation of restricted and illiquid securities normally reflect a discount, which may be significant, from the market price of comparable securities for which a more liquid market exists. Issuers of Rule 144A securities are required to furnish information to potential investors upon request. However, the required disclosure is much less extensive than that required of public companies and is not publicly available since it is not filed with the SEC. Further, issuers of Rule 144A securities can require recipients of the information (such as a Fund) to agree contractually to keep the information confidential, which could also adversely affect a Fund’s ability to dispose of the security.

At times, a Fund may have a significant portion of its assets invested in securities of companies conducting business in a related group of industries within an economic sector. Companies in the same economic sector may be similarly affected by economic, regulatory, political or market events or conditions, which may make a Fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly. The more broadly a Fund invests, the more it spreads risk and potentially reduces the risks of loss and volatility.

A Fund that establishes short positions introduces more risk to the Fund than a fund that only takes long positions (where the Fund owns the instrument or other asset) because the maximum sustainable loss on an

instrument or other asset purchased (held long) is limited to the amount paid for the instrument or other asset plus the transaction costs, whereas there is no maximum price of the shorted instrument or other asset when purchased in the open market. Therefore, in theory, short positions have unlimited risk. A Fund’s use of short positions in effect “leverages” the Fund. Leverage potentially exposes a Fund to greater risks of loss due to unanticipated market movements, which may magnify losses and increase the volatility of returns. To the extent a Fund takes a short position in a derivative instrument or other asset, this involves the risk of a potentially unlimited increase in the value of the underlying instrument or other asset.

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

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 the political constraints to which a sovereign debtor may be subject.

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 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 and that has led to defaults and the restructuring of certain indebtedness to the detriment of debtholders. Sovereign debt risk is increased for emerging market issuers.

Securities of companies that are involved in an initial public offering or a major corporate event, such as a business consolidation or restructuring, may be exposed to heightened 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. Initial public offerings are subject to many of the same risks as investing in companies with smaller market capitalizations. To the extent a Fund determines to invest in initial public offerings, it may not be able to invest to the extent desired, because, for example, only a small portion (if any) of the securities being offered in an initial public offering are available to the Fund. The investment performance of a Fund during periods when it is unable to invest significantly or at all in initial public offerings may be lower than during periods when a Fund is able to do so. Securities purchased in initial public offerings which are sold within 12 months of purchase may result in

increased short-term capital gains, which will be taxable to a Fund’s shareholders as ordinary income. Certain “special situation” investments are investments in securities or other instruments that are determined to be illiquid or lacking a readily ascertainable fair value. Certain special situation investments prevent ownership interests therein from being withdrawn until the special situation investment, or a portion thereof, is realized or deemed realized, which may negatively impact Fund performance. Investing in special situations may have a magnified effect on the performance of funds with small amounts of assets.

Stripped securities are the separate income or principal components of debt securities. These securities are particularly sensitive to changes in interest rates, and therefore subject to greater fluctuations in price than typical interest bearing debt securities. For example, stripped mortgage-backed securities have greater interest rate risk than mortgage-backed securities with like maturities, and stripped treasury securities have greater interest rate risk than traditional government securities with identical credit ratings.

The Investment Manager and its affiliates use various technology in managing the Funds, consistent with its investment objective and strategy described in each Fund’s prospectus. For example, proprietary and third-party data and systems may be utilized to support decision making for the Funds. Data imprecision, software or other technology malfunctions, programming inaccuracies and similar circumstances may impair the performance of these systems, which may negatively affect Fund performance. See also Cyber 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 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.

The sales price a Fund (or a Portfolio Fund or other investment vehicle) could receive for any particular investment may differ from the Fund’s (or a Portfolio Fund’s or other investment vehicle’s) valuation of the investment, particularly for securities that trade in thin or volatile markets or that are valued using a fair value methodology that produces an estimate of the fair value of the security/instrument, which may prove to be inaccurate. Investors who purchase or redeem Fund shares on days when a Fund is holding securities or other instruments (or holding shares of Portfolio Funds or other investment vehicles that have fair-valued securities or other instruments in their portfolios) may receive fewer or more shares or lower or higher redemption proceeds than they would have received if a Fund (or Portfolio Fund or other investment vehicle) had not fair-valued the security or instrument or had used a different valuation methodology. The value of foreign securities, certain fixed income securities and currencies, as applicable, may be materially affected by events after the close of the market on which they are valued, but before a Fund determines its net asset value.

Zero-coupon bonds are bonds that do not pay interest in cash on a current basis, but instead accrue interest over the life of the bond. As a result, these securities are issued at a discount and their values may fluctuate more than the values of similar securities that pay interest periodically. Although these securities pay no interest to holders prior to maturity, interest accrued on these securities is reported as income to a Fund and affects the amounts distributed to its shareholders, which may cause the Fund to sell investments to obtain cash to make income distributions to shareholders, including at times when it may not be advantageous to do so.

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 33¹/₃% 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 33¹/₃% 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.

A Fund may 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.

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.

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 designating on the Fund’s books and records 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 designated on the Fund’s books and records may not at any time be less than the market value of the securities sold short at the time of the short sale.

Securities lending refers to the lending of a Fund’s portfolio securities. GSAL serves as the Funds’ securities lending agent pursuant to a securities lending agreement approved by the Board. Each Fund (other than

Columbia Thermostat 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 has determined are creditworthy under guidelines established by the Board. A lending Fund pays a portion of income earned on lending transactions to GSAL, and also may pay administrative and custodial fees in connection with loans of securities.

The Funds receive collateral equal to at least 102% for domestic issuers and 105% for foreign issuers of the value of the securities loaned. Collateral is invested by the Funds in a third-party institutional government money market fund in accordance with investment guidelines contained in the securities lending agreement and approved by the Board. If the market value of the loaned securities goes up, the securities lending agent will require additional collateral from the borrower. If the market value of the loaned securities goes down, the borrower may request that some collateral be returned. Funds participating in securities lending bear the risk of loss in connection with investment of collateral received from the borrowers. To the extent that the value, including any investment return, of a Fund’s investment of the collateral declines below the amount owed to a borrower, a Fund may incur losses that exceed the amount it earned on lending the security.

Securities lending involves counterparty risk, including the risk that a borrower may not return a loaned security and the proceeds from the sale of the collateral will not be sufficient to replace the borrowed security. Counterparty risk also includes a potential loss of rights in the collateral if the borrower or the securities lending agent defaults or enters bankruptcy. This risk is increased if a Fund’s loans are concentrated with a single borrower or limited number of borrowers. 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. A Fund could also sustain losses arising from expenses of enforcing the Fund’s rights. GSAL has agreed to indemnify the Funds from losses resulting from a borrower’s failure to return a loaned security when due, but such indemnification does not extend to losses associated with declines in the value of collateral investments.

Loans are subject to termination at any time by the Funds or a borrower. 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.

During the existence of the loan, the borrower must pay over to the lender amounts equivalent to any dividends, interest or other distributions on the loaned securities, as well as interest on such amounts, less applicable taxes. Such payments 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 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 prospectus for that Fund.

Under normal conditions, the portfolio turnover rates for Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn Select and Columbia Acorn Emerging Markets Fund are expected to be below 50%, and for Columbia Acorn International Select and Columbia Acorn European Fund are expected to be below 75%.

For the fiscal year ended December 31, 2014, Columbia Thermostat Fund’s portfolio turnover rate was 95%, and for the fiscal year ended December 31, 2013, it was 92%. Columbia Thermostat Fund’s portfolio 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.

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.

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 columbiathreadneedle.com/us as of a month-end no earlier than 30 to 40 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 on 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.

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 sec.gov, a link to which is provided on the Funds’ website at columbiathreadneedle.com/us. 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.

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 sub-custodians, independent registered public accounting firm, legal counsel, operational system vendors, 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 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.

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 risk and 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.

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 March 31, 2015, the Investment Manager had assets under management of approximately $30.4 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.

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 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 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 of the Independent Trustees.

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, 2015, of the Advisory Agreement with respect to each Fund is available in the Funds’ semiannual report to shareholders for the fiscal period ended June 30, 2014. A discussion regarding the Board’s approval of the continuation, through July 31, 2016, of the Advisory Agreement with respect to each Fund is expected to be available in the Funds’ semiannual report to shareholders for the fiscal period ending June 30, 2015.

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 prospectus. The advisory fee is calculated as a percentage of the average daily net assets of each Fund and is paid monthly. 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 receives 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 columbiathreadneedle.com/us and on the SEC’s website at sec.gov.

The Investment Manager receives a monthly investment advisory fee based on each Fund’s average daily net assets at the following annual rates:

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.

With respect to Columbia Acorn International, the Transfer Agent, an affiliate of the Investment Manager, has voluntarily agreed to waive a portion of the Fund’s total annual operating expenses attributable to transfer agency fees incurred by Class A, Class B and Class C shares of the Fund such that its total annual operating expenses will be reduced by 0.04%, 0.03% and 0.02% for Class A, Class B and Class C shares, respectively. This arrangement may be modified or discontinued at any time.

With respect to Columbia Acorn Select, the Investment Manager has contractually agreed to waive 0.20% of the advisory fee otherwise payable to it by the Fund through April 30, 2016. When determining whether Columbia Acorn Select’s total expenses exceed the additional voluntary expense cap described below, the Fund’s net advisory fee, reflecting application of the 0.20% waiver, will be used to calculate the Fund’s total expenses. The Investment Manager is not entitled to collect on or make a claim for waived fees that are the subject of this undertaking at any time in the future. This arrangement may only be modified or amended with approval from all parties to the arrangement, including the Fund and the Investment Manager.

In addition, the Investment Manager has voluntarily agreed to reimburse a portion of the expenses of Columbia Acorn Select and Columbia Acorn International Select (excluding transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund’s investment

in other investment companies, if any) so that ordinary operating expenses do not exceed (i) the annual rates of 1.60% for Class A shares, 2.10% for Class B shares, 2.35% for Class C shares, 1.25% for Class I shares, 1.35% for Class R4 shares, 1.30% for Class R5 shares, 1.25% for Class Y shares and 1.35% for Class Z shares for Columbia Acorn Select, and (ii) the annual rates of 1.70% for Class A shares, 2.20% for Class B shares, 2.45% for Class C shares, 1.37% for Class I shares, 1.45% for Class R4 shares, 1.42% for Class R5 shares, 1.37% for Class Y shares and 1.45% for Class Z shares for Columbia Acorn International Select. 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 transaction costs and certain other investment-related expenses, interest and fees on borrowings and expenses associated with the Fund’s investment in the Portfolio Funds (acquired funds)) do not exceed the annual rates of 0.50% for Class A shares, 1.00% for Class B shares, 1.25% for Class C shares, 0.25% for Class R4 shares, 0.24% for Class R5 shares, 0.19% for Class Y shares and 0.25% for Class Z shares, through April 30, 2016. 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 transaction costs and certain other investment-related expenses, 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% for Class A shares, 2.50% for Class C shares, 1.41% for Class I shares, 1.50% for Class R4 shares, 1.46% for Class R5 shares and 1.50% for Class Z shares, through April 30, 2016. 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 transaction costs and certain other investment-related expenses, 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 above, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This arrangement may only be modified or amended with approval from all parties to the arrangement, 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 transaction costs and certain other investment-related expenses, 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% for Class A shares, 2.60% for Class C shares, 1.48% for Class I shares, 1.60% for Class R4 shares, 1.53% for Class R5 shares, 1.48% for Class Y shares and 1.60% for Class Z shares, through April 30, 2016. 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 transaction costs and certain other investment-related expenses, 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 above, or to exceed such annual rate as may be in place at the time of the recoupment, whichever is less. This arrangement may only be modified or amended with approval from all parties to the arrangement, 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.

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 prospectus, the portfolio managers of the Investment Manager who are responsible for the Funds are:

For services performed for the 2014 calendar year and incentives paid in early 2015, Messrs. Chalupnik, Doyle, Egan, Frank, 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 and their total responsibilities, the objective being to provide very competitive total compensation for high performing analysts and portfolio managers. Portfolio manager performance is measured versus primary portfolio benchmarks. Analyst performance is measured versus a custom benchmark for each analyst. The Funds’ portfolio managers are compensated both as portfolio managers (versus their primary portfolio benchmarks) and as analysts (versus their custom analyst benchmarks). One-, three- and five-year performance periods primarily drove incentive levels through 2014, with the three-year period carrying the highest weight. Incentive compensation varies by tier and can range from zero on the low end to a multiple of base pay on the high end. Incentives are adjusted up or down by as much as 15% of high/low ranges 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 are 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 adhering to the formulas, subject to review by Columbia Management and Ameriprise Financial. For Mr. Mohn’s 2014 compensation, Ameriprise Financial and the Investment Manager agreed to subject the standard formulas to a floor.

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.

Other Accounts Managed by the Portfolio Managers for which the Advisory Fee is Based on Performance

As of December 31, 2014, none of the Funds’ portfolio managers managed an account for which the advisory fee was based on performance.

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.

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 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 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.

CWAM (which is also the Investment Manager) serves as Administrator of the Funds.

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 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.

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 prospectus.

The following chart shows the administration fees paid to the Administrator for the three most recently completed fiscal years.

The Administrator did not waive or reimburse any Fund’s administration fees for the fiscal years ended December 31, 2014, December 31, 2013 or December 31, 2012.

Columbia Management Investment 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.

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 the 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.

The following table shows all commissions and other compensation received by the Distributor, as well as amounts the Distributor retained, after paying commissions and other expenses, during the Funds’ three most recent fiscal years.

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 the Funds’ 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 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. Fund investors should also be aware that Fund assets may be used to compensate the Transfer Agent for payments made to Ameriprise and its affiliates for providing shareholder servicing or “sub-transfer agency” services. 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 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, Ameriprise Financial 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 investment advice to and make investment 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, Ameriprise Financial 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 by the Investment Manager, Ameriprise Financial or other Ameriprise Financial affiliates 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, Ameriprise Financial 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 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.

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.

Certain products and services, commonly referred to as “soft dollar services” (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.

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.

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.

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.

Subject to applicable legal and regulatory requirements, a Fund may enter into transactions in which Ameriprise Financial and/or its affiliates, or companies that are deemed to be affiliates of a Fund because of, among other factors, their or their affiliates’ ownership or control of shares of the Fund, may have an interest that potentially conflicts with the interests of the Fund. For example, an affiliate of Ameriprise Financial may sell securities to a Fund from an offering in which it is an underwriter or that it owns as a dealer, subject to applicable legal and regulatory requirements.

Regulatory and other restrictions may limit a Fund’s investment activities in various ways. For example, certain securities may be subject to ownership limitations due to regulatory limits on investments in certain industries (such as, for example, banking and insurance) and markets (such as emerging or international markets), or certain transactions (such as those involving certain derivatives or other instruments) or mechanisms imposed by certain issuers (such as, among others, poison pills). Certain of these restrictions may impose limits on the aggregate amount of investments that may be made by affiliated investors in the aggregate or in individual issuers. In these circumstances, the Investment Manager may be prevented from acquiring securities for a Fund (that it might otherwise prefer to acquire) if the acquisition would cause the Fund and its affiliated investors to exceed an applicable limit. These types of regulatory and other applicable limits are complex and vary significantly in different contexts including, among others, from country to country, industry to industry and issuer to issuer. The Investment Manager has policies and procedures designed to monitor and interpret these limits. Nonetheless, given the complexity of these limits, the Investment Manager and/or its affiliates may inadvertently breach these limits, and a Fund may therefore be required to sell securities that it might otherwise prefer to hold in order to comply with such limits. In addition, aggregate ownership limitations could cause performance dispersion among funds and accounts managed by the Investment Manager with similar investment objectives and strategies and portfolio management teams. For example, if further purchases in an issuer are restricted due to regulatory or other reasons, a portfolio manager would not be able to acquire securities or other assets of an issuer for a new fund that may already be held by other funds and accounts with the same/similar investment objectives and strategies that are managed by the same portfolio management team. The Investment Manager may also choose to limit purchases in an issuer to a certain threshold for risk management purposes. If the holdings of the Investment Manager’s affiliates are included in that limitation, a Fund may be more limited in its ability to purchase a particular security or other asset than if the holdings of the Investment Manager’s affiliates had been excluded from the limitation. At certain times, a Fund may be restricted in its investment activities because of relationships that an affiliate of the Fund, which may include Ameriprise Financial and its affiliates, may have with the issuers of securities. This could happen, for example, if a Fund desired to buy a security issued by a company for which Ameriprise Financial or an affiliate serves as underwriter. In any of these scenarios, a Fund’s inability to participate (or participate further) in a particular investment, despite a portfolio manager’s desire to so participate, may negatively impact Fund performance. The internal policies and

procedures of Ameriprise Financial and its affiliates covering these types of restrictions and addressing similar issues also may at times restrict a Fund’s investment activities. 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.

Columbia Management Investment Services Corp. acts as Transfer Agent for each Fund’s shares and can be contacted 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 or “sub-transfer agency” 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. DST/BFDS is located at 2 Heritage Drive, North Quincy, MA 02171. In addition, the Transfer Agent enters into agreements with various financial intermediaries through which investors may hold Fund shares, including Ameriprise Financial and its affiliates. These intermediaries also may provide Shareholder Services for which they are compensated by the Transfer Agent, which is in turn compensated by the Funds as described below. For more information, see Brokerage Allocation and Other Practices — Additional Shareholder Servicing Payments.

Effective May 1, 2013, the Funds pay the Transfer Agent an annual base per account fee of $20.00 (payable monthly) for each account (other than Class I share accounts) held directly with the Transfer Agent and compensate 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 with respect to shareholder accounts established or maintained pursuant to the National Securities Clearing Corporation’s (NSCC) networking system. A significant portion of such networking account fees are paid by the Transfer Agent to dealer firms affiliated with Ameriprise Financial and its affiliates.

In addition, subject to certain limitations, the Funds compensate the Transfer Agent for payments made 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. Effective May 1, 2013, each Fund in the Columbia Acorn Family of Funds compensates the Transfer Agent for the cost of Shareholder Services at a rate of (i) 0.18% of the average aggregate value of the Fund’s shares attributable to retirement plan sponsors, defined contribution plans, 529 plans (together, “Plans”) or other financial intermediaries that maintain omnibus accounts with the Fund and provide recordkeeping services to beneficial shareholders in the Plans (including retirement plan accounts maintained by certain mutual fund trading platforms (also known as “fund supermarkets”)); or (ii) an annual fee of $14.00 for each open sub-account beneficially invested in the Fund through an omnibus account maintained by a fund supermarket, broker-dealer firm or other financial intermediary not covered by clause (i), provided that 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. The Transfer Agent does not pay financial intermediaries for Shareholder Services and the Funds do not compensate the Transfer Agent for any Shareholder Services provided by financial intermediaries with respect to Class I and Class Y shares. Amounts in excess of those paid by a Fund are borne by the Distributor, the Investment Manager and/or their affiliates.

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.

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.

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.

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. The report of the Funds’ independent registered public accounting firm and the audited financial statements included in the Funds’ annual report to shareholders dated December 31, 2014 are incorporated herein by reference. No other part of the annual report is incorporated by reference herein. The audited financial statements incorporated by reference into the Funds’ 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.

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.

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. See About the Funds’ Investments — Lending Securities for more information.

The Trustees have approved the 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 distribution or service fees. Under the Distribution Plan, each Fund pays the Distributor monthly distribution and service fees, as applicable, at the annual rates described in the Fund’s prospectus. 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 Funds’ prospectuses for details.

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 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, 2014

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 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.

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, columbiathreadneedle.com/us, (ii) by calling Columbia Funds at 800.426.3750 or (iii) through the SEC’s website at 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.

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 serves a term of unlimited duration and 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.

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.

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 a non-voting Trustee Emeritus of the Trust. The Chair of the Board, Laura M. Born, is an Independent Trustee.

P. Zachary Egan is considered an Interested Trustee because he is an officer of the Funds and of the Investment Manager.

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:

The Board has established seven standing committees: the Audit Committee; the Compliance Committee; the Contract Committee; the Executive Committee; the Governance Committee; the Investment Performance Analysis Committee; and the Valuation Committee. The Board has also established an Ad Hoc Committee on IT/Data Security. The Trustees believe that the number of standing and ad hoc 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.

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 Governance Committee identifies Trustee candidates 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 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 chair of the Governance Committee promptly upon receipt.

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 Investment Performance Analysis Committee also receives regular reports from GSAL 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, operational 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, operational, investment 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.

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 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 associate professor of finance. Ms. Born has experience analyzing and evaluating financial statements of issuers as a result of her investment banking experience. Ms. Born has experience with board functions through her former position as a director of a subsidiary of a major private company and her current position as a director of a major private company. She 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 eight years.

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 eight years.

P. Zachary Egan. Mr. Egan has investment, business, finance and regulatory experience through his positions as president, international chief investment officer and director of international research of the Investment Manager, as well as through his more than 15 years of experience as a portfolio manager and/or analyst of the Investment Manager. Through these roles, Mr. Egan has significant experience with Board operations and understands the business of the Investment Manager and the Funds.

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, her position as a director of a college board and her position as the lead trustee of another registered investment 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 13 years.

Thomas M. Goldstein. Mr. Goldstein has financial, accounting, management, operations and risk management experience through his various senior executive positions with financial services businesses, including as the chairman and chief executive officer of a large mortgage company and chief financial officer of a large mid-western bank. He has familiarity with complex financial, banking and audit issues having served as the chief financial officer for a banking operation, a large property and casualty insurance business and a private equity firm. Therefore, the Board believes that Mr. Goldstein is qualified to serve as the chair of the Audit Committee and as the Audit Committee financial expert. Mr. Goldstein also is familiar with board operations through his service on the boards of directors of the Federal Home Loan Bank of Chicago and the Federal Home Loan Mortgage Corporation.

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 five 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 School of Business where he teaches finance and business economics classes to masters and doctoral candidates. Mr. Kaplan has experience with board functions through the positions he holds as a director of two public operating companies, and has experience in the investment management industry as one of these public operating companies 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 16 years.

Charles R. Phillips. Mr. Phillips has investment, financial and regulatory experience through working for almost 30 years in the financial services industry. He has direct investment experience, having served as vice chairman and client account manager for high net worth clients of a private bank within a large banking firm. Mr. Phillips is familiar with analyzing and evaluating financial statements of issuers and investment advisers as a result of his investment experience. Mr. Phillips has experience with board functions through his position as a director of a private foundation.

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 in the financial services sector. 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 five years.

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 45 years. Mr. Wanger serves as a non-voting Trustee Emeritus of the Trust.

Trustees are compensated for their services to the Columbia Funds Family on a complex-wide basis, as shown in the table below.

Independent Trustee Compensation for the Fiscal Year Ended December 31, 2014

Interested Trustee and Trustee Emeritus Compensation for the Fiscal Year Ended December 31, 2014

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 Class Z shares of one or more of the Funds or in shares of Columbia Money Market 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.

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, 2014

Interested Trustee Ownership for the Calendar Year Ended December 31, 2014

The following table provides basic information about the officers of the Trust, other than Mr. Egan, 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.

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

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.

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.

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.

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.

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.

The Funds paid no brokerage commissions to affiliated broker-dealers for the fiscal years ended December 31, 2014, December 31, 2013 and December 31, 2012.

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.

During the fiscal year ended December 31, 2014, 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.

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, 2014, the Funds owned securities of the following “regular broker or dealers” or their parents, as defined in Rule 10b-1 under the 1940 Act:

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 otherwise 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 compensate the Transfer Agent for payments made 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 paid 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 National Securities Clearing Corporation (NSCC). A significant portion of these networking account fees are paid to Selling Agents affiliated with Ameriprise Financial and its affiliates.

In addition, the Distributor and other Ameriprise Financial affiliates may make lump sum payments to selected Selling Agents receiving shareholder servicing payments as compensation for the costs of printing literature for participants, account maintenance fees or fees for establishment of the Funds on the Selling Agent’s system or other similar services.

As of April 2015, the Transfer Agent 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 Transfer Agent and/or other Ameriprise Financial affiliates

The Transfer Agent 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.

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 prospectus.

The Distributor and its affiliates 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, systems infrastructure support and data analytics. 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 0.40% 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, the Investment Manager and other Ameriprise Financial affiliates make payments with respect to a Fund or the Columbia Funds in materially larger amounts or on a basis materially different from those described above when dealing with certain Selling Agents, including certain affiliates of Bank of America Corporation. Such increased payments may enable such Selling Agents to offset credits that they may provide to their customers.

As of April 2015, 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.

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.

From time to time, the Distributor, from its own resources, typically 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 includes 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.

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).

The Funds offer shares in the classes shown in the table below. Subject to certain limited exceptions discussed in each Fund’s prospectus, 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.

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.

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.

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.

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 prospectus and this SAI, the Trustees shall continue to hold office and may appoint their successors.

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.

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.

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 prospectus.

Each Fund’s dividend, distribution and redemption policies can be found in its prospectus 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.

All Fund shares are issued in uncertificated form only and when issued will be fully paid and non-assessable by the Trust.

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.

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.

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

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.

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:

Refer to the Funds’ 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.

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.

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

below, Fund positions for which market quotations are not readily available are valued at a fair value as determined in good faith by the Valuation Committee of the Board 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. The Valuation Committee of the Board values securities which have halted or temporarily stopped trading at the last sale price, adjusted by a premium or discount to account for the anticipated re-opening price. The Valuation Committee values securities for which there is no bid or ask prices. Equity securities that are not listed on any national exchange or NASDAQ are generally valued at the last sale 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 that 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. Although the value of foreign securities owned by the Funds could change on days when Fund shares cannot be bought or sold, Fund NAVs are not calculated, and therefore a Fund’s foreign holdings are not priced, on such days. 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 intraday spot rate as of the NYSE close, 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.

Rather than using the methods described above, in the event that price quotations or valuations are not readily available or are deemed unreliable, the security will be valued in good faith based on a determination of the security’s fair value pursuant to the Trust’s Portfolio Pricing Policy approved by the Board. For example, a security may be fair valued when trading is halted or if the security is not actively traded, such as is the case with 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.

Fair values of securities are determined following the Trust’s Portfolio Pricing Policy, utilizing the valuation methodology set forth in the Policy and deemed most appropriate in the circumstances and considering all available, relevant factors and indications of value in reaching its decision. To the extent a factor is deemed relevant, the following non-exhaustive list of factors is used in reaching a fair value determination for a security under the Policy: the value of other financial instruments, including derivative securities; trading volumes; values of baskets of securities; changes in 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. Significant events occurring after the close of a foreign exchange but before the time at which a Fund calculates the price of its foreign portfolio securities may lead to a determination that it is appropriate to fair value the affected foreign securities. Such significant events affecting a foreign security may include, but are not limited to: (i) extraordinary corporate events such as a reorganization, redemption, conversion; (ii) a trading halt in a domestic or foreign exchange; (iii) stale prices; (iv) suspension of trading in an individual security or market; (v) extraordinary market, economic or political events; (vi) scheduled and unscheduled foreign market closures; and (vii) such other instances as the Investment Manager or the Valuation Committee may determine.

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 E-Mini Index (the “S&P 500 E-Mini”). In the event of such a movement, under the Trust’s Portfolio Pricing Policy adjusted or “fair value” prices must be obtained 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 E-Mini. When a foreign security is fair valued, the fair valuation adjustment factor supplied by the vendor may 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.

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. Except as specifically set forth below, 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.

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 (other than a qualified publicly traded 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 (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 gross 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. In general, such entities will be treated as partnerships for federal income tax purposes if they meet the passive-type income requirement under Code section 7704(c)(2). 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 loss 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 the 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) other securities, limited in respect 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 (other than securities of other regulated investment companies) 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, as well as the extent to which it can invest in MLPs.

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 that is accorded special tax treatment, 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. Each Fund generally intends to distribute at least annually substantially all of its investment company taxable income (computed without regard to the dividends-paid deduction) and its net 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 or net capital gain retained by a Fund will be subject to tax at regular corporate rates.

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 mailed within 60 days of the close of the Fund’s taxable year 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, including in connection with determining the amount available to support a Capital Gain Dividend (as defined below), its taxable income, and its earnings and profits, a regulated investment company generally may elect to treat part or all of any post-October capital loss (defined as the greatest of net capital loss, net long-term capital loss, or net short-term capital loss, in each case attributable to the portion of the taxable year after October 31) or late-year ordinary loss (generally, (i) net ordinary loss from the sale, exchange or other taxable disposition of property, attributable to the portion of the taxable year after October 31, plus (ii) other net ordinary loss attributable to the portion of the taxable year after December 31) as if incurred in the succeeding taxable 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. Shareholders generally are taxed on any net distributions from a Fund in the year they are actually distributed. 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 the Fund were to fail to meet the income, diversification or distribution tests described above, the Fund could in some cases cure such failure including by paying a fund-level tax or interest, making additional distributions, or disposing of certain assets. If the Fund were ineligible to or otherwise did not cure such failure for any year, or were otherwise to fail to qualify and be eligible for treatment as a regulated investment company accorded special tax treatment under the Code, it would be taxed in the same manner as an ordinary corporation without any deduction for its distributions to shareholders. In this case, 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 would 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.

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 or December 31 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 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 carryover 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 carryover 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 eight-year carryover 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 capital gains so offset. The Funds cannot carry back or carry forward any net operating losses.

Each Fund may use the so-called “equalization method” of accounting to allocate a portion of its “accumulated earnings and profits,” which generally equals a Fund’s undistributed net investment income and realized capital gains, with certain adjustments, to redemption proceeds. This method permits a Fund to achieve more balanced distributions for both continuing and redeeming shareholders. Although using this method generally will not affect a Fund’s total returns, it may reduce the amount of income and gains that the Fund would otherwise distribute to continuing shareholders by reducing the effect of redemptions of Fund shares on Fund distributions to shareholders. The IRS has not sanctioned the particular equalization method used by the Funds, and thus a Fund’s use of this method may be subject to IRS scrutiny.

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. A portion of the interest paid or accrued on certain high-yield discount obligations (such as high-yield corporate debt securities) may not (and interest paid on debt obligations owned by a Fund or a Portfolio Fund that are considered for tax purposes to be payable in the equity of the issuer or a related party will not) be deductible to the issuer, possibly affecting the cash flow of the issuer.

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 eligibility for treatment as a regulated investment company and does not become subject to U.S. federal income or excise tax.

Very generally, when a Fund or a Portfolio Fund purchases a bond at a price that exceeds the redemption price at maturity — that is, at a premium — the premium is amortizable over the remaining term of the bond. In the case of a taxable bond, if a Fund or a Portfolio Fund makes an election applicable to all such bonds it purchases, which election cannot be revoked without consent of the IRS, the Fund or the Portfolio Fund reduces the current taxable income from the bond by the amortized premium and reduces its basis in the bond by the amount of such offset; upon the disposition or maturity of such bonds acquired on or after January 4, 2013, a Fund or a Portfolio Fund is permitted to deduct any remaining premium allocable to a prior period. In the case of a tax-exempt bond, tax rules require a Fund or a Portfolio Fund to reduce its tax basis by the amount of the amortized premium.

If an option granted by a Fund is sold, lapses or is otherwise terminated through a closing transaction, such as a repurchase by the Fund of the option from its holder, the Fund generally will realize a short-term capital gain or loss, depending on whether the premium income is greater or less than the amount paid by the Fund in the closing transaction. Some capital losses realized by a Fund in the sale, exchange, exercise or other disposition of an option may be deferred if they result from a position that is part of a “straddle,” discussed below. If securities are sold by a Fund pursuant to the exercise of a covered call option granted by it, the Fund generally will add the premium received to the sale price of the securities delivered in determining the amount of gain or loss on the sale. If securities are purchased by a Fund pursuant to the exercise of a put option written by it, the Fund generally will subtract the premium received from its cost basis in the securities purchased.

Some regulated futures contracts, foreign currency contracts, and non-equity, listed options that may be used by a Fund will be deemed “Section 1256 contracts.” A Fund will be required to “mark to market” any such

contracts held at the end of the taxable year by treating them as if they had been sold on the last day of that year at market value. Sixty percent of any net gain or loss realized on all dispositions of Section 1256 contracts, including deemed dispositions under the “mark-to-market” rule, generally will be treated as long-term capital gain or loss, and the remaining 40% will be treated as short-term capital gain or loss, although certain foreign currency gains and losses from such contracts may be treated as entirely ordinary income or loss as described below. These provisions may require a Fund to recognize income or gains without a concurrent receipt of cash. Transactions that qualify as designated hedges are exempt from the mark-to-market rule and the “60%/40%” rule and may require the Fund to defer the recognition of losses on certain futures contracts, foreign currency contracts, and non-equity options.

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 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 carryover and thus cannot be deducted by the Fund or its shareholders in future years.

Offsetting positions held by a Fund involving certain derivative instruments, such as forward, futures and options contracts, may be considered, for U.S. federal income tax purposes, to constitute “straddles.” “Straddles” are defined to include “offsetting positions” in actively traded personal property. The tax treatment of “straddles” is governed by Section 1092 of the Code which, in certain circumstances, overrides or modifies the provisions of Section 1256. If a Fund is treated as entering into a “straddle” and at least one (but not all) of the Fund’s positions in derivative contracts comprising a part of such straddle is governed by Section 1256 of the Code, described above, then such straddle could be characterized as a “mixed straddle.” A Fund may make one or more elections with respect to “mixed straddles.” Depending upon which election is made, if any, the results with respect to a Fund may differ. Generally, to the extent the straddle rules apply to positions established by a Fund, losses realized by the Fund may be deferred to the extent of unrealized gain in any offsetting positions. Moreover, as a result of the straddle rules, short-term capital loss on straddle positions may be recharacterized as long-term capital loss, and long-term capital gain may be characterized as short-term capital gain. In addition, the existence of a straddle may affect the holding period of the offsetting positions. As a result, the straddle rules could cause distributions that would otherwise constitute “qualified dividend income” or qualify for the dividends-received deduction to fail to satisfy the applicable holding period requirements (as described below). Furthermore, the Fund may be required to capitalize, rather than deduct currently, any interest expense and carrying charges applicable to a position that is part of a straddle, including any interest on indebtedness incurred or continued to purchase or carry any positions that are part of a straddle. The application of the straddle rules to certain offsetting Fund positions can therefore affect the amount, timing, and character of distributions to shareholders, and may result in significant differences from the amount, timing and character of distributions that would have been made by the Fund if it had not entered into offsetting positions in respect of certain of its portfolio securities.

If a Fund enters into a “constructive sale” of any appreciated financial position in stock, a partnership interest, or certain debt instruments, the Fund will be treated as if it had sold and immediately repurchased the property and must recognize gain (but not loss) with respect to that position. A constructive sale of an appreciated financial position occurs when a Fund enters into certain offsetting transactions with respect to the same or substantially identical property, including, but not limited to: (i) a short sale; (ii) an offsetting notional principal contract; (iii) a futures or forward contract; or (iv) other transactions identified in future Treasury Regulations. The character of the gain from constructive sales will depend upon a Fund’s holding period in the

appreciated financial position. Losses realized from a sale of a position that was previously the subject of a constructive sale will be recognized when the position is subsequently disposed of. The character of such losses will depend upon a Fund’s holding period in the position beginning with the date the constructive sale was deemed to have occurred and the application of various loss deferral provisions in the Code. Constructive sale treatment does not apply to certain closed transactions, including if such a transaction is closed on or before the 30th day after the close of the Fund’s taxable year and the Fund holds the appreciated financial position unhedged throughout the 60-day period beginning with the day such transaction was closed.

The amount of long-term capital gain a Fund may recognize from certain derivative transactions with respect to interests in certain pass-through entities is limited under the Code’s constructive ownership rules. The amount of long-term capital gain is limited to the amount of such gain the Fund would have had if the Fund directly invested in the pass-through entity during the term of the derivative contract. Any gain in excess of this amount is treated as ordinary income. An interest charge is imposed on the amount of gain that is treated as ordinary income.

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, such 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 such 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.

In addition, a Fund’s transactions in securities and certain types of derivatives (e.g., options, futures contracts, forward contracts and swap agreements) may be subject to other special tax rules, such as 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, 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. These rules could therefore affect the amount, timing and character of distributions to shareholders.

Certain of a Fund’s investments in derivative instruments and foreign currency-denominated instruments, as well as any of its foreign currency transactions and hedging activities, 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 for treatment as a regulated investment company that is accorded special tax treatment.

Rules governing the U.S. federal income tax aspects of derivatives, including swap agreements and 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.

A Fund may invest directly or indirectly in residual interests in real estate mortgage investment conduits (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 real estate investment trust (REIT), a regulated investment company or other 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 (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.

Some amounts received by a Fund from its investments in master limited partnerships (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 that are characterized as ordinary income under the Code’s recapture provisions will be taxable to shareholders as ordinary income.

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 non-qualifying 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 certain interest, dividends, rents and royalties, or capital gains) or at least 50% of their assets on average produce such passive income or are held for the production of 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. Excess distributions and gain from the sale of interests in PFICs may be characterized as ordinary income even though, absent the application of PFIC rules, these amounts may otherwise have been classified as capital gain.

A Fund will not be permitted to pass through to its shareholders any credit or deduction for these special taxes and interest charges incurred with respect to a PFIC. 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 accelerate the recognition of gain and may 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 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.

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 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 net asset value 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, 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 at ordinary income rates. Distributions properly reported by a Fund as capital gain dividends (Capital Gain 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 report Capital Gain Dividends, if any, in written statements furnished to its shareholders.

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.

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 held) 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 incurs a sales charge in acquiring Fund shares and sells or exchanges those 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 (including through the reinvestment of dividends) 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 deemed long-term capital gain distribution. If Fund shares are sold at a loss after being held for six months or less, the loss generally will be disallowed to the extent of any exempt-interest dividends (defined below) received on those shares. However, this loss disallowance does not apply with respect to redemptions of Fund shares with a holding period beginning after December 22, 2010 if such Fund declares substantially all of its net tax-exempt income as exempt-interest dividends on a daily basis, and pays such dividends on at least a monthly basis (as would typically be the case for tax-exempt money market funds).

Each Fund generally is required to report to shareholders and the IRS gross proceeds on sales, redemptions or exchanges of Fund shares. In addition, for shares purchased, including shares purchased through dividend reinvestment, on or after January 1, 2012, the Funds (or the shareholder’s Selling Agent, if Fund shares are held through a Selling Agent) generally are required to provide the shareholders 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 a Fund, each Fund will calculate and report cost basis using the Fund’s default method of average cost, unless the shareholder instructs the Fund to use a different calculation method. A Fund will not report cost basis for shares whose cost basis is uncertain or unknown to the Fund. Please visit the Columbia Funds’ website at columbiathreadneedle.com/us or contact the Funds 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 a shareholder retains Fund shares through a Selling Agent, he or she should contact their Selling Agent to learn about the Fund’s cost basis reporting default method and the reporting elections available to his or her account. The Funds do not recommend any particular method of determining cost basis. The shareholder should consult a tax advisor to determine which available cost basis method is best. When completing U.S. federal and state income tax returns, shareholders should carefully review the cost basis and other information provided and make any additional basis, holding period or other adjustments that may be required.

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. In some cases, a Fund may also be eligible to pass through to its shareholders the foreign taxes paid by underlying funds (as defined below) in which it invests that themselves elected to pass through such taxes to their shareholders, see Special Tax Considerations Pertaining to Funds of Funds below.

For taxable years beginning after December 22, 2010, certain Funds may qualify for and make the election; however, even if a Fund qualifies for the election for any year, it may determine not to make the election for such year. If a Fund does not so qualify or qualifies but does not so elect, then shareholders will not be entitled to claim a credit or deduction with respect to foreign taxes paid by or withheld from payments to the Fund. A Fund will notify its shareholders in written statements if it has elected for the foreign taxes paid by it to “pass through” for that year.

In general, if a Fund makes the election, the Fund itself will not be permitted to claim a credit or deduction for foreign taxes paid in that year, and the Fund’s dividends-paid deduction will be increased by the amount of foreign taxes paid that year. Fund shareholders generally shall include their proportionate share of the foreign taxes paid by the Fund in their gross income and treat that amount as paid by them for the purpose of the foreign tax credit or deduction, provided that any applicable holding period and other requirements have been met. If a shareholder claims a credit for foreign taxes paid, in general, the credit will be subject to certain limits. A deduction for foreign taxes paid may be claimed only by shareholders that itemize their deductions. Shareholders that are not subject to U.S. federal income tax, and those who invest in the Fund through tax-exempt accounts (including those who invest through IRAs or other tax-advantaged retirement plans), generally will receive no benefit from any tax credit or deduction passed through by the Fund.

Certain Funds (each such fund, a Fund of Funds) invest their assets primarily in shares of other mutual funds, ETFs or other companies that are regulated investment companies (collectively, underlying funds). Consequently, their income and gains will normally consist primarily of distributions from underlying funds and gains and losses on the disposition of shares of underlying funds. To the extent that an underlying fund realizes net losses on its investments for a given taxable year, a Fund of Funds will not be able to benefit from those

losses until (i) the underlying fund realizes gains that it can reduce by those losses, or (ii) the Fund of Funds recognizes its share of those losses (so as to offset distributions of net income or capital gains from other underlying funds) when it disposes of shares of the underlying fund. Moreover, even when a Fund of Funds does make such a disposition, a portion of its loss may be recognized as a long-term capital loss, which will not be treated as favorably for U.S. federal income tax purposes as a short-term capital loss or an ordinary deduction. In particular, a Fund of Funds will not be able to offset any capital losses from its dispositions of underlying fund shares against its ordinary income (including distributions of any net short-term capital gains realized by an underlying fund).

In addition, in certain circumstances, the “wash sale” rules may apply to sales of underlying fund shares by a Fund of Funds. As discussed above, a wash sale occurs if shares of an underlying fund are sold by a Fund of Funds at a loss and the Fund of Funds acquires additional shares of that same underlying fund 30 days before or after the date of the sale. The wash-sale rules could defer losses of a Fund of Funds on sales of underlying fund shares (to the extent such sales are wash sales) for extended (and, in certain cases, potentially indefinite) periods of time.

As a result of the foregoing rules, and certain other special rules, it is possible that the amounts of net investment income and net capital gain that a Fund of Funds will be required to distribute to shareholders will be greater than such amounts would have been had the Fund of Funds invested directly in the securities held by the underlying funds, rather than investing in shares of the underlying funds. For similar reasons, the character of distributions from a Fund of Funds (e.g., long-term capital gain, exempt interest, eligibility for dividends-received deduction) will not necessarily be the same as it would have been had the Fund of Funds invested directly in the securities held by the underlying funds.

Depending on the percentage ownership of a Fund of Funds in an underlying fund before and after a redemption of underlying fund shares, the redemption of shares by the Fund of Funds of such underlying fund may cause the Fund of Funds to be treated as receiving a dividend in the full amount of the redemption proceeds instead of receiving a capital gain or loss on the redemption of shares of the underlying fund. This could be the case where a Fund of Funds holds a significant interest in an underlying fund that is not “publicly offered” (as defined in the Code) and redeems only a small portion of such interest. Dividend treatment of a redemption by a Fund of Funds would affect the amount and character of income required to be distributed by both the Fund of Funds and the underlying fund for the year in which the redemption occurred. It is possible that such a dividend would qualify as “qualified dividend income;” otherwise, it would be taxable as ordinary income and could cause shareholders of a Fund of Funds to recognize higher amounts of ordinary income than if the shareholders had held shares of the underlying fund directly.

If a Fund of Funds receives dividends from an underlying fund, and the underlying fund reports such dividends as “qualified dividend income,” as discussed below, then the Fund of Funds is permitted, in turn, to report a portion of its distributions as “qualified dividend income,” provided the Fund of Funds meets the holding period and other requirements with respect to shares of the underlying fund. If a Fund of Funds receives dividends from an underlying fund, and the underlying fund reports such dividends as eligible for the dividends-received deduction, then the Fund of Funds is permitted, in turn, to report a portion of its distributions as eligible for the dividends-received deduction, provided the Fund of Funds meets the holding period and other requirements with respect to shares of the underlying fund.

If a Fund of Funds is a “qualified fund of funds” (a regulated investment company that invests at least 50% of its total assets in other regulated investment companies at the close of each quarter of its taxable year), it will be able to distribute exempt-interest dividends and thereby pass through to its shareholders the tax-exempt character of any interest received on tax exempt obligations in which it directly invests or any exempt-interest dividends it receives from underlying funds in which it invests.

Further, if a Fund of Funds is a qualified fund of funds, it will be able to elect to pass through to its shareholders any foreign income and other similar taxes paid by the Fund of Funds or paid by an underlying fund in which the Fund of Funds invests that itself elected to pass such taxes through to shareholders, so that shareholders of the Fund of Funds will be eligible to claim a tax credit or deduction for such taxes. However, even if a Fund of Funds qualifies to make the election for any year, it may determine not to do so. For further considerations pertaining to foreign taxes paid by a Fund, see Foreign Taxes above.

The maximum stated U.S. federal income tax rate applicable to individuals generally is 39.6% for ordinary income and 20% for net long-term capital gain (in each case, not including the 3.8% Medicare contribution tax described below).

In general, “qualified dividend income” is income attributable to dividends received by a Fund 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 gross income is attributable to qualified dividend income, then only the portion of the Fund’s distributions that is attributable to qualified dividend income and reported as such in a timely manner will be so treated in the hands of individual shareholders who meet the aforementioned holding period requirements. Qualified dividend income is taxable to individual shareholders at tax rates applicable to long-term capital gain. 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. Fixed income funds typically do not distribute significant amounts of qualified dividend income.

The Code generally imposes a 3.8% Medicare contribution tax on certain high-income individuals, trusts and estates. For individuals, the 3.8% tax applies 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. Certain details of the implementation of the tax 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.

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 reported as exempt-interest dividends (defined above). 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 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.

The maximum stated corporate U.S. federal income tax rate applicable to ordinary income and net capital gain is currently 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.

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. For information regarding eligibility for the dividends-received deduction of dividend income derived by an underlying fund in which a Fund of Funds invests, see Special Tax Considerations Pertaining to Funds of Funds above. 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.

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, dividend distributions made to foreign shareholders other than Capital Gain Dividends and exempt-interest dividends (defined above) 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, 2014, distributions made to foreign shareholders and properly reported by a Fund as “interest-related dividends” were exempt from U.S. federal income tax 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 is 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 is a related person of the foreign shareholder and the foreign shareholder was a controlled foreign corporation. Interest-related dividends were generally dividends 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 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 reported 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; (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; or (iii) the Fund shares on which the foreign shareholder realized gain constitute U.S. real property interests (USRPIs, defined below) or, in certain cases, the distributions are attributable to gain from the sale or exchange of a USRPI, as discussed below. 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 as may be provided under an applicable income tax treaty). Please see below for a discussion of the tax implications to foreign shareholders in the event that clause (iii) applies. With respect to taxable years of a Fund beginning before January 1, 2014, a distribution 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 statement, furnished to its shareholders (“short-term capital gain dividends”) was generally not subject to U.S. federal income or withholding tax unless clause (i), (ii) or (iii) above applied to such distributions.

This exemption from withholding for interest-related and short-term capital gain dividends has expired for distributions with respect to taxable years of a Fund beginning on or after January 1, 2014. Therefore, as of the date of this SAl, each Fund (or intermediary, as applicable) is currently required to withhold on distributions to foreign shareholders attributable to net interest or short-term capital gains that were formerly eligible for this withholding exemption. It is currently unclear whether Congress will extend this exemption for distributions with respect to taxable years of a Fund beginning on or after January 1, 2014, or what the terms of such an extension would be, including whether 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 reports a payment as exempt from U.S. federal withholding tax (e.g., as a short-term capital gain or interest-related dividend), no assurance can be made that the intermediary will respect such a classification, and an intermediary may withhold in spite of such reporting by a Fund. Foreign shareholders should contact their intermediaries regarding the application of these rules to their accounts.

Special rules apply to distributions to foreign shareholders from a Fund if it is either a “U.S. real property holding corporation” (USRPHC) or would be a USRPHC but for the operation of certain exemptions from USRPI treatment for interests in domestically controlled real estate investment trust (REIT) (or, prior to January 1, 2014, 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 Fund if it is a USRPHC. Generally, a USRPHC is a domestic corporation that holds U.S. real property interests

(USRPIs) — 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.

However, if a Fund holds (directly or indirectly) significant interests in REITs, it may be a USRPHC. If a Fund is a USRPHC or would be a USRPHC but for certain of the above-mentioned exceptions, under a special “look-through” rule, amounts that are attributable directly or indirectly to distributions received by the Fund from a lower-tier REIT that the Fund is required to treat as USRPI gain in its hands generally will retain their character as such in the hands of the Fund’s foreign shareholders. Prior to January 1, 2014, this special “look-through” rule described above for distributions by the Fund to foreign shareholders also applied to distributions attributable to (i) gains realized on the disposition of USRPIs by the Fund and (ii) distributions received by the Fund from a lower-tier RIC that the Fund was required to treat as USRPI gain in its hands. It is currently unclear whether Congress will extend these former “look-through” provisions to distributions made on or after January 1, 2014, and what the terms of any such extension would be, including whether any such extension would have retroactive effect. In the hands of a foreign shareholder that holds (or has held in the prior 12 months) more than a 5% interest in any class of the Fund, any such amounts treated as USRPI gains generally will be treated as gains “effectively connected” with the conduct of a “U.S. trade or business,” and subject to tax at graduated rates.

Moreover, such shareholder generally will be required to file a U.S. income tax return for the year recognized, and the Fund must withhold 35% of the amount of such distribution. Otherwise, in the case of all other foreign shareholders (i.e., those whose interest in any class of the Fund did not exceed 5% at any time during the prior 12 months), such amounts generally will be treated as ordinary income (regardless of whether the Fund otherwise reported such distribution as a short-term capital gain dividend or Capital Gain Dividend), and the Fund must withhold 30% (or a lower applicable treaty rate) of the amount of the distribution paid to such shareholders. If a Fund is subject to the rules of this paragraph, its foreign shareholders may also be subject to “wash sale” rules to prevent the avoidance of the foregoing tax-filing and payment obligations through the sale and repurchase of Fund shares.

Prior to January 1, 2014, the special “look-through” rule discussed above for distributions by the Fund to foreign shareholders also applied to distributions attributable to (i) gains realized by on the disposition of USRPIs by the Fund and (ii) distributions received by the Fund from a lower-tier RIC that the Fund was required to treat as USRPI gain in its hands. It is currently unclear whether Congress will extend these former “look-through” provisions to distributions made on or after January 1, 2014, and what the terms of any such extension would be, including whether any such extension would have retroactive effect.

In addition, if a Fund is a USRPHC, it generally must withhold 10% of the amount realized in redemption by a greater-than-5% foreign shareholder, and that shareholder must file a U.S. income tax return for the year of the disposition of the USRPI and pay any additional tax due on the gain. Prior to January 1, 2014, such withholding generally was not required with respect to amounts paid in redemption of shares of a Fund if it was a domestically controlled USRPHC, or, in certain limited cases, if the Fund (whether or not domestically controlled) held substantial investments in regulated investment companies that were domestically controlled USRPHCs. The exemption from withholding for redemptions has expired and such withholding is required without regard to whether the Fund or any regulated investment company in which it invests is domestically controlled. It is currently unclear whether Congress will extend this exemption for redemptions made on or after January 1, 2014, and what the terms of any such extension would be, including whether any such extension would have retroactive effect.

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 advisors 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.

Each Fund 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 taxable mortgage pools (TMPs). Furthermore, any investment in residual interests of a collateralized mortgage obligation that has elected to be treated as a real estate mortgage investment conduit (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.

Shareholder Reporting Obligations With Respect to Foreign Bank and Financial Accounts

Shareholders that are U.S. persons and own, directly or indirectly, more than 50% of a Fund could be required to report annually their “financial interest” in the Fund’s “foreign financial accounts,” if any, on FinCEN Form 114, Report of Foreign Bank and Financial Accounts (FBAR). Shareholders should consult a tax advisor, and persons investing in the Fund through an intermediary should contact their intermediary, regarding the applicability to them of this reporting requirement.

The Foreign Account Tax Compliance Act (FATCA), which took effect July 1, 2014, generally requires a Fund to obtain information sufficient to identify the status of each of its shareholders under FATCA, as described more fully below. If a shareholder fails to provide this information or otherwise fails to comply with FATCA, the Fund may be required to withhold under FATCA at a rate of 30% with respect to that shareholder on dividends (other than exempt interest dividends), including Capital Gain Dividends and the proceeds of the sale, redemption or exchange of Fund shares. If a payment by a Fund is subject to FATCA withholding, the Fund is required to withhold even if such payment would otherwise be exempt from withholding under the rules applicable to foreign shareholders described above (e.g., Capital Gain Dividends and short-term capital gain and interest-related dividends).

Payments to a shareholder will generally not be subject to FATCA withholding, provided the shareholder provides a Fund with such certifications, waivers or other documentation or information as the Fund requires, including, to the extent required, with regard to such shareholder’s direct and indirect owners, to establish the shareholder’s FATCA status and otherwise to comply with these rules. In order to avoid withholding, a shareholder that is a “foreign financial institution” (FFI) must either (i) become a “participating FFI” by entering into a valid U.S. tax compliance agreement with the IRS, (ii) qualify for an exception from the requirement to enter into such an agreement, for example by becoming a “deemed-compliant FFI,” or (iii) be covered by an applicable intergovernmental agreement between the United States and a non-U.S. government to implement FATCA and improve international tax compliance. In any of these cases, the investing FFI generally will be required to provide its Fund with appropriate identifiers, certifications or documentation concerning its status.

A Fund may disclose the information that it receives from (or concerning) its shareholders to the IRS, non-U.S. taxing authorities or other parties as necessary to comply with FATCA, related intergovernmental agreements or other applicable law or regulation.

Each prospective investor is urged to consult its tax adviser regarding the applicability of FATCA and any other reporting requirements with respect to the prospective investor’s own situation, including investments through an intermediary.

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 IRS 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.

As of March 31, 2015, the Trustees and the officers of the Trust, as a group, owned less than 1% of the outstanding equity securities of each Fund, except that (i) the tables below identify individual officers of the Trust who beneficially own greater than 1% of the outstanding shares of Columbia Acorn European Fund, (ii) the Trustees and officers of the Trust together beneficially own approximately 1.5% of Columbia Acorn Emerging Markets Fund, approximately 1.1% of Columbia Acorn International Select, approximately 1.3% of Columbia Acorn Select and approximately 1.1% of Columbia Thermostat Fund and (iii) in addition to the officers of the Trust listed in the tables below, the other officers of the Trust and the Trustees together beneficially own approximately 2.8% of Columbia Acorn European Fund.

As of March 31, 2015, the name, address and percentage of ownership of each person, including certain Trustees and certain officers of Trust, who may be deemed to be a “principal holder” of a Fund as that term is defined in the 1940 Act (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) or a “control person” of a Fund as that term is defined in the 1940 Act (i.e., owns of record or is known by the Trust to own greater than 25% of a Fund’s 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 shareholders.

This Appendix A summarizes the various descriptions of securities ratings applicable to securities purchased by the Columbia Funds Family. The ratings of S&P, Moody’s and Fitch represent their opinions as to quality. These ratings are not absolute standards of quality and are not recommendations to purchase, sell or hold a security. Issuers and issues are subject to risks that are not evaluated by the rating agencies. 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 A.

An obligation rated ‘AAA’ has the highest rating assigned by S&P. The obligor’s capacity to meet its financial commitment on the obligation is extremely strong.

An obligation rated ‘AA’ differs from the highest-rated obligations only to a small degree. The obligor’s capacity to meet its financial commitment on the obligation is very strong.

An obligation rated ‘A’ is somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than obligations in higher-rated categories. However, the obligor’s capacity to meet its financial commitment on the obligation is still strong.

An obligation rated ‘BBB’ exhibits adequate protection parameters. However, adverse economic conditions or changing circumstances are more likely to lead to a weakened capacity of the obligor to meet its financial commitment on the obligation.

Obligations rated ‘BB’, ‘B’, ‘CCC’, ‘CC’, and ‘C’ are regarded as having significant speculative characteristics. ‘BB’ indicates the least degree of speculation and ‘C’ the highest. While such obligations will likely have some quality and protective characteristics, these may be outweighed by large uncertainties or major exposures to adverse conditions.

An obligation rated ‘BB’ is less vulnerable to nonpayment than other speculative issues. However, it faces major ongoing uncertainties or exposure to adverse business, financial, or economic conditions which could lead to the obligor’s inadequate capacity to meet its financial commitment on the obligation.

An obligation rated ‘B’ is more vulnerable to nonpayment than obligations rated ‘BB’, but the obligor currently has the capacity to meet its financial commitment on the obligation. Adverse business, financial, or economic conditions will likely impair the obligor’s capacity or willingness to meet its financial commitment on the obligation.

An obligation rated ‘CCC’ is currently vulnerable to nonpayment, and is dependent upon favorable business, financial, and economic conditions for the obligor to meet its financial commitment on the obligation. In the event of adverse business, financial, or economic conditions, the obligor is not likely to have the capacity to meet its financial commitment on the obligation.

An obligation rated ‘CC’ is currently highly vulnerable to nonpayment. The ‘CC’ rating is used when a default has not yet occurred, but S&P expects default to be a virtual certainty, regardless of the anticipated time to default.

An obligation rated ‘C’ is currently highly vulnerable to nonpayment, and the obligation is expected to have lower relative seniority or lower ultimate recovery compared to obligations that are rated higher.

An obligation rated ‘D’ is in default or in breach of an imputed promise. For non-hybrid capital instruments, the ‘D’ rating category is used when payments on an obligation are not made on the date due, unless S&P believes that such payments will be made within five business days in the absence of a stated grace period or within the earlier of the stated grace period or 30 calendar days. The ‘D’ rating also will be used upon the filing of a bankruptcy petition or the taking of similar action and where default on an obligation is a virtual certainty, for example due to automatic stay provisions. An obligation’s rating is lowered to ‘D’ if it is subject to a distressed exchange offer.

Short-term ratings are generally assigned to those obligations considered short-term in the relevant market. In the U.S., for example, that means obligations with an original maturity of no more than 365 days — including commercial paper.

A short-term obligation rated ‘A-1’ is rated in the highest category by S&P. The obligor’s capacity to meet its financial commitment on the obligation is strong. Within this category, certain obligations are designated with a plus sign (+). This indicates that the obligor’s capacity to meet its financial commitment on these obligations is extremely strong.

A short-term obligation rated ‘A-2’ is somewhat more susceptible to the adverse effects of changes in circumstances and economic conditions than obligations in higher rating categories. However, the obligor’s capacity to meet its financial commitment on the obligation is satisfactory.

A short-term obligation rated ‘A-3’ exhibits adequate protection parameters. However, adverse economic conditions or changing circumstances are more likely to lead to a weakened capacity of the obligor to meet its financial commitment on the obligation.

A short-term obligation rated ‘B’ is regarded as vulnerable and has significant speculative characteristics. The obligor currently has the capacity to meet its financial commitments; however, it faces major ongoing uncertainties which could lead to the obligor’s inadequate capacity to meet its financial commitments.

A short-term obligation rated ‘C’ is currently vulnerable to nonpayment and is dependent upon favorable business, financial, and economic conditions for the obligor to meet its financial commitment on the obligation.

A short-term obligation rated ‘D’ is in default or in breach of an imputed promise. For non-hybrid capital instruments, the ‘D’ rating category is used when payments on an obligation are not made on the date due, unless S&P believes that such payments will be made within any stated grace period. However, any stated grace period longer than five business days will be treated as five business days. The ‘D’ rating also will be used upon the filing of a bankruptcy petition or the taking of a similar action and where default on an obligation is a virtual certainty, for example due to automatic stay provisions. An obligation’s rating is lowered to ‘D’ if it is subject to a distressed exchange offer.

An ‘SP-1’ rating indicates strong capacity to pay principal and interest. An issue determined to possess a very strong capacity to pay debt service is given a plus (+) designation.

An ‘SP-2’ rating indicates satisfactory capacity to pay principal and interest, with some vulnerability to adverse financial and economic changes over the term of the notes.

An ‘SP-3’ rating indicates speculative capacity to pay principal and interest.

Aaa — Obligations rated Aaa are judged to be of the highest quality, subject to the lowest level of credit risk.

Aa — Obligations rated Aa are judged to be of high quality and are subject to very low credit risk.

A — Obligations rated A are judged to be upper-medium grade and are subject to low credit risk.

Baa — Obligations rated Baa are judged to be medium-grade and subject to moderate credit risk and as such may possess certain speculative characteristics.

Ba — Obligations rated Ba are judged to be speculative and are subject to substantial credit risk.

B — Obligations rated B are considered speculative and are subject to high credit risk.

Caa — Obligations rated Caa are judged to be speculative of poor standing and are subject to very high credit risk.

Ca — Obligations rated Ca are highly speculative and are likely in, or very near, default, with some prospect of recovery of principal and interest.

C — Obligations rated C are the lowest rated and are typically in default, with little prospect for recovery of principal or interest.

Issuers (or supporting institutions) rated Prime-1 (P-1) have a superior ability to repay short-term debt obligations.

Issuers (or supporting institutions) rated Prime-2 (P-2) have a strong ability to repay short-term debt obligations.

Issuers (or supporting institutions) rated Prime-3 (P-3) have an acceptable ability to repay short-term obligations.

Issuers (or supporting institutions) rated Not Prime (NP) do not fall within any of the Prime rating categories.

While the global short-term ‘prime’ rating scale is applied to U.S. municipal tax-exempt commercial paper, these programs are typically backed by external letters of credit or liquidity facilities and their short-term prime ratings usually map to the long-term rating of the enhancing bank or financial institution and not to the municipality’s rating. Other short-term municipal obligations, which generally have different funding sources for repayment, are rated using two additional short-term rating scales (i.e., the MIG and VMIG scales discussed below).

The Municipal Investment Grade (MIG) scale is used to rate US municipal bond anticipation notes of up to three years maturity. Municipal notes rated on the MIG scale may be secured by either pledged revenues or proceeds of a take-out financing received prior to note maturity. MIG ratings expire at the maturity of the

obligation, and the issuer’s long-term rating is only one consideration in assigning the MIG rating. MIG ratings are divided into three levels — MIG 1 through MIG 3 — while speculative grade short-term obligations are designated SG.

The MIG 1 designation denotes superior credit quality. Excellent protection is afforded by established cash flows, highly reliable liquidity support, or demonstrated broad-based access to the market for refinancing.

The MIG 2 designation denotes strong credit quality. Margins of protection are ample, although not as large as in the preceding group.

The MIG 3 designation denotes acceptable credit quality. Liquidity and cash-flow protection may be narrow, and market access for refinancing is likely to be less well-established.

The SG designation denotes speculative-grade credit quality. Debt instruments in this category may lack sufficient margins of protection.

In the case of variable rate demand obligations (VRDOs), a two-component rating is assigned: a long or short-term debt rating and a demand obligation rating. The first element represents Moody’s evaluation of risk associated with scheduled principal and interest payments. The second element represents Moody’s evaluation of risk associated with the ability to receive purchase price upon demand (“demand feature”). The second element uses a rating from a variation of the MIG scale called the Variable Municipal Investment Grade (VMIG) scale. The rating transitions on the VMIG scale, as shown in the diagram below, differ from those on the Prime scale to reflect the risk that external liquidity support generally will terminate if the issuer’s long-term rating drops below investment grade.

The VMIG 1 designation denotes superior credit quality. Excellent protection is afforded by the superior short-term credit strength of the liquidity provider and structural and legal protections that ensure the timely payment of purchase price upon demand.

The VMIG 2 designation denotes strong credit quality. Good protection is afforded by the strong short-term credit strength of the liquidity provider and structural and legal protections that ensure the timely payment of purchase price upon demand.

The VMIG 3 designation denotes acceptable credit quality. Adequate protection is afforded by the satisfactory short-term credit strength of the liquidity provider and structural and legal protections that ensure the timely payment of purchase price upon demand.

The SG designation denotes speculative-grade credit quality. Demand features rated in this category may be supported by a liquidity provider that does not have an investment grade short-term rating or may lack the structural and/or legal protections necessary to ensure the timely payment of purchase price upon demand.

AAA: Highest credit quality. ‘AAA’ ratings denote the lowest expectation of credit risk. They are assigned only in cases of exceptionally strong capacity for payment of financial commitments. This capacity is highly unlikely to be adversely affected by foreseeable events.

AA: Very high credit quality. ‘AA’ ratings denote expectations of very low credit risk. They indicate very strong capacity for payment of financial commitments. This capacity is not significantly vulnerable to foreseeable events.

A: High credit quality. ‘A’ ratings denote expectations of low credit risk. The capacity for payment of financial commitments is considered strong. This capacity may, nevertheless, be more vulnerable to adverse business or economic conditions than is the case for higher ratings.

BBB: Good credit quality. ‘BBB’ ratings indicate that expectations of credit risk are currently low. The capacity for payment of financial commitments is considered adequate but adverse business or economic conditions are more likely to impair this capacity.

BB: Speculative. ‘BB’ ratings indicate an elevated vulnerability to credit risk, particularly in the event of adverse changes in business or economic conditions over time; however, business or financial alternatives may be available to allow financial commitments to be met.

B: Highly speculative. ‘B’ ratings indicate that material credit risk is present.

CCC: Substantial credit risk. ‘CCC’ ratings indicate that substantial credit risk is present.

CC: Very high levels of credit risk. ‘CC’ ratings indicate very high levels of credit risk.

C: Exceptionally high levels of credit risk. ‘C’ indicates exceptionally high levels of credit risk.

Defaulted obligations typically are not assigned ‘RD’ or ‘D’ ratings, but are instead rated in the ‘B’ to ‘C’ rating categories, depending upon their recovery prospects and other relevant characteristics. This approach better aligns obligations that have comparable overall expected loss but varying vulnerability to default and loss.

Short-Term Ratings Assigned to Issuers or Obligations in Corporate, Public and Structured Finance

F1: Highest short-term credit quality. Indicates the strongest intrinsic capacity for timely payment of financial commitments; may have an added “+” to denote any exceptionally strong credit feature.

F2: Good short-term credit quality. Good intrinsic capacity for timely payment of financial commitments.

F3: Fair short-term credit quality. The intrinsic capacity for timely payment of financial commitments is adequate.

B: Speculative short-term credit quality. Minimal capacity for timely payment of financial commitments, plus heightened vulnerability to near term adverse changes in financial and economic conditions.

RD: Restricted default. Indicates an entity that has defaulted on one or more of its financial commitments, although it continues to meet other financial obligations. Typically applicable to entity ratings only.

D: Default. Indicates a broad-based default event for an entity, or the default of a short-term obligation.

APPENDIX B — THE INVESTMENT MANAGER’S PROXY VOTING POLICY AND PROCEDURES MANUAL

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.

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.

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:

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

Employees’ Retirement System but does not have authority to vote proxies for the State of Oregon or the 1199 SEIU Healthcare Employees Pension Fund.

CWAM or ISS shall vote proxies for portfolio securities held in the Acorn and WAT funds.

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 or ISS shall vote proxies on securities held in the Montlake UCITS (Wanger US Smaller Companies and Wanger European Smaller Companies).

The authority to vote proxies on securities held in the VP Wanger Funds are reserved to the client. CWAM or ISS has authority to vote proxies on securities held in the Optimum Small Cap Growth Fund.

CWAM has established a Proxy Committee, which consists of the Chief Compliance Officer, Domestic Chief Investment Officer, the Director of Accounting and Operations and a designated International Portfolio Manager. 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 International Chief Investment Officer may serve as alternate members for proxy voting purposes and to break a voting tie. Please see Appendix A of the Proxy Committee Charter for Proxy Committee membership and voting eligibility.

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).

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. However, CWAM will abstain from voting proxies when a ballot is received for a company CWAM no longer owns.

Following are some guidelines CWAM uses with respect to voting on specific matters:

CWAM generally 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. Should an analyst believe a director has or will be detrimental to shareholder interest, or when director elections are contested, the analyst’s recommendation and vote should be forwarded to the Proxy Committee for a full vote.

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.

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.

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.

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.

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.

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.

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.

Occasionally proxy statements ask the shareholders to vote on whether to require a majority vote in the case of election of directors, or whether all directors should be elected annually (eliminating staggered boards). Analysts should vote in favor of these proposals without consulting the Proxy Committee.

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.

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.

From time to time, the Funds may be invested in other Mutual Funds, ETF’s or Money Market Funds. Those Funds may also have proxy votes for CWAM to vote. CWAM’s Director of Accounting and Operations may vote these proxies, according to this policy, if the vote is routine. If such proxies are not routine, then those would be voted either by CWAM’s Domestic CIO (for Money Market Funds) or the relevant Portfolio Manager (for non-Money Market Mutual Funds or ETF’s held in their Funds). As previously stated, Thermostat “echo votes” and is an exception from this policy.

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.

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.

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:

The annual report should be submitted as soon as practicable after the close of the proxy voting season which normally concludes in June.

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 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 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 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.

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.

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:

For purposes of obtaining a breakpoint discount for Class A shares or Class T 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 under 21, step-child under 21, 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.

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:

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) 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.

Shareholders won’t pay a CDSC upon redemptions of Class A, Class B or Class C shares:

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.

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:

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:

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 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.

Columbia Acorn Emerging Markets Fund Closed to Most New Investors and New Accounts

Columbia Acorn Emerging Markets Fund is closed to most new investors and new accounts, subject to the following limited exceptions:

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 have continuously held 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 as long as the initial Class Z account was funded by July 2, 2013.

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.

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).

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.

A Systematic Withdrawal Plan allows you to schedule regular redemptions from your account any day of the month on a monthly, quarterly or semi-annual basis. Currently, Systematic Withdrawal Plans are generally available for Class A, B, C, R4, R5, Y and Z share accounts. 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. 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.

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 Investment Manager” and in the statement of additional information under the caption “The Investment Manager and Investment Advisory Services” is incorporated by reference.

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.

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 Registrant has entered into Indemnification Agreements with each of the independent trustees which provide that the Registrant 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 Registrant 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 Registrant 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, as amended, 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.

The information in the prospectuses under the caption “Management of the Fund - Primary Service Providers - The Investment Manager” 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.

(a) Columbia Management Investment Distributors, Inc. (“CMID”), an affiliate of Columbia Management Investment Advisers, LLC (“Columbia Management”), 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 Fund Series Trust II, Columbia Funds Variable Insurance Trust I, Columbia Funds Variable Series Trust II 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 Columbia Management or its affiliates and principally underwritten by CMID).

(b) The tables below lists each director or officer of the principal underwriter named in the answer to Item 25.

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.

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 April 30, 2015.

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.

Class		Ticker Symbol
Class A Shares		CAGAX
Class C Shares		CGMCX
Class I Shares		CATIX
Class R4 Shares		CAERX
Class R5 Shares		CANRX
Class Y Shares		CPHRX
Class Z Shares		CEFZX


TABLE OF CONTENTS

SAI PRIMER					2
ABOUT THE TRUST					5
ABOUT THE FUNDS’ INVESTMENTS					6
Certain Investment Activity Limits					6
Fundamental and Non-Fundamental Investment Policies					6
Permissible Investments					13
Information Regarding Risks					56
Borrowings					80
Short Sales					80
Lending Securities					81
Portfolio Turnover					82
Disclosure of Portfolio Information					83
INVESTMENT ADVISORY AND OTHER SERVICES					88
The Investment Manager and Investment Advisory Services					88
The Administrator					98
The Principal Underwriter/Distributor					99
Other Roles and Relationships of Ameriprise Financial and its Affiliates — Certain Conflicts of Interest					102
Other Service Providers					106
Codes of Ethics					109
Proxy Voting Policies and Procedures					109
FUND GOVERNANCE					111
BROKERAGE ALLOCATION AND OTHER PRACTICES					126
Brokerage Commissions					129
Directed Brokerage					129
Securities of Regular Broker-Dealers					130
Additional Shareholder Servicing Payments					130
Additional Selling Agent Payments					132
Performance Disclosure					133
CAPITAL STOCK AND OTHER SECURITIES					135
Description of the Trust’s Shares					135
PURCHASE, REDEMPTION AND PRICING OF SHARES					138
Purchase and Redemption					138
Offering Price					139
Fair Valuation of Portfolio Securities					140
TAXATION					142
CONTROL PERSONS AND PRINCIPAL SHAREHOLDERS					160
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


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

CFTC		The Commodity Futures Trading Commission, a U.S. government agency

Code		Internal Revenue Code of 1986, as amended



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 (including Columbia Management) and principally underwritten by the Distributor, including the Columbia Funds Family

Columbia Funds or Columbia Funds Family		The funds within the Columbia Funds Complex, including the Columbia Acorn Funds and the Columbia Wanger 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		The plan 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.

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

GSAL		Goldman Sachs Agency Lending, the Funds’ securities lending agent

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

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)

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.

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.

Sub-Administrator		Columbia Management

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


	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


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**


IDENTITY OF RECIPIENT	PURPOSE OF DISCLOSURE	FREQUENCY OF DISCLOSURE
Wilshire Associates	Provides supportive performance analysis software.	Daily

JPMorgan	Funds’ Custodian; receives trade files containing information for the Funds.	Daily

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

Financial Tracking, LLC	Provides automated review for purposes of Code of Ethics and other compliance monitoring.	Daily

GSAL	Funds’ securities lending agent.	As needed in connection with the Funds’ securities lending program


	Assets	Rate of Fee
Columbia Acorn Fund	Up to $700 million	0.740%
	$700 million to $2 billion	0.690%
	$2 billion to $6 billion	0.640%
	$6 billion and over	0.630%

Columbia Acorn International	Up to $100 million	1.190%
	$100 million to $500 million	0.940%
	$500 million and over	0.740%

Columbia Acorn USA	Up to $200 million	0.940%
	$200 million to $500 million	0.890%
	$500 million to $2 billion	0.840%
	$2 billion to $3 billion	0.800%
	$3 billion and over	0.700%

Columbia Acorn Select	Up to $700 million	0.850%
	$700 million to $2 billion	0.800%
	$2 billion to $3 billion	0.750%
	$3 billion and over	0.700%

Columbia Acorn International Select	Up to $500 million	0.940%
	$500 million and over	0.900%

Columbia Thermostat Fund	All assets	0.100%

Columbia Acorn European Fund	Up to $100 million	1.190%
	$100 million to $500 million	0.940%
	$500 million and over	0.740%

Columbia Acorn Emerging Markets Fund	Up to $100 million	1.250%
	$100 million to $500 million	1.000%
	$500 million and over	0.800%


Fund	Fiscal Year Ended December 31, 2014		Fiscal Year Ended December 31, 2013			Fiscal Year Ended December 31, 2012
Columbia Acorn Fund
Gross Advisory Fee	$	123,279,339	$	125,835,656		$	112,165,480
Amount Waived/Reimbursed by the Investment Manager		—		—			—
Net Advisory Fee	$	123,279,339	$	125,835,656		$	112,165,480
Columbia Acorn International
Gross Advisory Fee	$	62,943,042	$	57,575,576		$	47,191,198
Amount Waived/Reimbursed by the Investment Manager	$	452,267	$	484,488		$	414,204
Net Advisory Fee	$	62,490,775	$	57,091,088		$	46,776,994
Columbia Acorn USA
Gross Advisory Fee	$	13,670,928	$	14,096,687		$	14,027,089
Amount Waived/Reimbursed by the Investment Manager		—		—			—
Net Advisory Fee	$	13,670,928	$	14,096,687		$	14,027,089
Columbia Acorn Select
Gross Advisory Fee	$	6,450,443	$	7,461,971		$	9,810,516
Amount Waived/Reimbursed by the Investment Manager	$	854	$	918			—
Net Advisory Fee	$	6,449,589	$	7,461,053		$	9,810,516
Columbia Acorn International Select
Gross Advisory Fee	$	3,181,739	$	3,429,562		$	3,407,749
Amount Waived/Reimbursed by the Investment Manager		—	$	3			—
Net Advisory Fee	$	3,181,739	$	3,429,559		$	3,407,749
Columbia Acorn European Fund
Gross Advisory Fee	$	590,149	$	117,559		$	26,888
Amount Waived/Reimbursed by the Investment Manager	$	147,638	$	186,331		$	242,324
Net Advisory Fee	$	442,511	$	(68,772	)	$	(215,436	)
Columbia Acorn Emerging Markets Fund
Gross Advisory Fee	$	5,370,711	$	1,966,358		$	78,222
Amount Waived/Reimbursed by the Investment Manager		—	$	61,620		$	292,249
Net Advisory Fee	$	5,370,711	$	1,904,738		$	(214,027	)
Columbia Thermostat Fund
Gross Advisory Fee	$	1,290,957	$	1,211,226		$	482,102
Amount Waived/Reimbursed by the Investment Manager	$	135,531	$	216,529		$	321,910
Net Advisory Fee	$	1,155,426	$	994,697		$	160,192


Portfolio Manager		Fund
Robert A. Chalupnik, CFA		Columbia Acorn Select
William J. Doyle, CFA		Columbia Acorn USA
P. Zachary Egan, CFA		Columbia Acorn International Columbia Acorn Fund
David L. Frank, CFA		Columbia Acorn Fund
Fritz Kaegi, CFA		Columbia Acorn Emerging Markets Fund Columbia Acorn Fund
Stephen Kusmierczak, CFA		Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund
Satoshi Matsunaga, CFA		Columbia Acorn Emerging Markets Fund
Charles P. McQuaid, CFA		Columbia Thermostat Fund
Louis J. Mendes, CFA		Columbia Acorn International Columbia Acorn Emerging Markets Fund
Robert A. Mohn, CFA		Columbia Acorn Fund Columbia Acorn USA
Christopher J. Olson, CFA		Columbia Acorn International Select Columbia Thermostat Fund
Matthew S. Szafranski, CFA		Columbia Acorn Select
Andreas Waldburg-Wolfegg		Columbia Acorn European Fund Columbia Acorn International Select


Portfolio Manager		Benchmark(s)
Robert A. Chalupnik (Columbia Acorn Select)		S&P MidCap 400^® Index (primary benchmark), S&P 500^® Index and Lipper Mid-Cap Core Funds Index
William J. Doyle (Columbia Acorn USA)		Russell 2000 Index (primary benchmark) and Lipper Small-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 Fund)		Russell 2500 Index (primary benchmark), S&P 500^® Index, Russell 2000 Index and Lipper Mid-Cap Growth Funds Index
David L. Frank (Columbia Acorn Fund)		Russell 2500 Index (primary benchmark), S&P 500^® Index, Russell 2000 Index and Lipper Mid-Cap Growth Funds 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 (Net) and Lipper Emerging Markets Index
Fritz Kaegi (Columbia Acorn Fund)		Russell 2500 Index (primary benchmark), S&P 500^® Index, Russell 2000 Index and Lipper Mid-Cap Growth Funds Index
Stephen Kusmierczak (Columbia Acorn European Fund)		S&P Europe $500 Million to $5 Billion^® Index (primary benchmark), Euromoney Smaller European Companies (inc UK) 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 (Net) and Lipper Emerging Markets Index
Satoshi Matsunaga (Columbia Acorn Emerging Markets Fund)		S&P Emerging Markets $500 Million to $5 Billion^® Index (primary benchmark), MSCI Emerging Markets Small Cap Index (Net) and Lipper Emerging Markets 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)


Portfolio Manager		Benchmark(s)
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 (Net) 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
Christopher J. Olson (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)
Matthew S. Szafranski (Columbia Acorn Select)		S&P MidCap 400^® Index (primary benchmark), S&P 500^® Index and Lipper Mid-Cap Core Funds Index
Andreas Waldburg-Wolfegg (Columbia Acorn European Fund)		S&P Europe $500 Million to $5 Billion^® Index (primary benchmark), Euromoney Smaller European Companies (inc UK) Index and Lipper European Region Index
Andreas Waldburg-Wolfegg (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


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
Robert A. Chalupnik		2	$	462,470,111		—		—		1	$	614,087
William J. Doyle		1	$	800,932,783		—		—		5	$	3,434,855
P. Zachary Egan		1	$	310,744,038		—		—		6	$	4,437,443
David L. Frank		1	$	348,983,743		—		—		6	$	894,890,941
Fritz Kaegi		—		—		—		—		5	$	3,273,874
Stephen Kusmierczak		—		—		1	$	11,170,247		6	$	2,685,979
Satoshi Matsunaga⁽¹⁾		—		—		—		—		10	$	1,239,720
Charles P. McQuaid		—		—		—		—		6	$	62,981,242


Portfolio Manager	Fund	Dollar Range of Equity Securities in the Fund Beneficially Owned

Robert A. Chalupnik	Columbia Acorn USA Columbia Acorn Select Columbia Acorn International Select Columbia Acorn European Fund Columbia Acorn Emerging Markets Fund	$500,001 – $1,000,000 over $1 million $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000

William J. Doyle	Columbia Acorn Fund Columbia Acorn International Columbia Acorn USA Columbia Acorn International Select Columbia Acorn Emerging Markets Fund Columbia Thermostat Fund	$100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000 $50,001 – $100,000 $10,001 – $50,000

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	$100,001 – $500,000 over $1 million $100,001 – $500,000 $10,001 – $50,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000

David L. Frank	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	$500,001 – $1,000,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000 $100,001 – $500,000


	Class A Shares Fiscal Year Ended December 31, 2014
	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		$1,435,758		$592,622		$85,622		$50,998		$49,250		$81,450		$314,720		$1,181,699
Initial sales charges retained by the Distributor		$199,830		$83,593		$12,291		$7,243		$6,924		$11,598		$44,436		$168,392
Aggregate CDSC on Fund redemptions retained by the Distributor		$12,592		$6,544		$1,772		$21		$1		$30		$5,137		$21,521


	Class B Shares Fiscal Year Ended December 31, 2014
	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		$438		$1,004		—		$194		—		—		—		$53


	Class C Shares Fiscal Year Ended December 31, 2014
	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		$31,848		$7,646		$2,679		$1,816		$865		$1,175		$8,322		$74,964


Fund	Class A Shares		Class B Shares		Class C Shares		Class R Shares
Columbia Acorn Fund
Distribution and Service Fee	$	8,592,952	$	90,223	$	8,701,253		—

Columbia Acorn International
Distribution and Service Fee	$	2,667,608	$	72,788	$	1,126,925	$	31,579

Columbia Acorn USA
Distribution and Service Fee	$	449,365	$	2,594	$	380,797		—

Columbia Acorn Select
Distribution and Service Fee	$	737,403	$	13,589	$	554,669		—

Columbia Acorn International Select
Distribution and Service Fee	$	175,936	$	4,608	$	100,087		—

Columbia Acorn European Fund
Distribution and Service Fee	$	71,873		—	$	40,802		—

Columbia Acorn Emerging Markets Fund
Distribution and Service Fee	$	516,453		—	$	414,504		—

Columbia Thermostat Fund
Distribution and Service Fee	$	1,212,958	$	12,184	$	4,156,486		—


Name, Position Held with the Trust and Age at March 31, 2015	Year First Appointed or Elected to a Board in the Columbia Funds Complex⁽¹⁾	Principal Occupation(s) During the Past Five Years	Number of Funds in the Columbia Funds Complex Overseen⁽²⁾	Other Directorships Held by Trustee During the Past Five Years
Laura M. Born, 50, Trustee and Chair	2007	Adjunct Associate Professor of Finance, University of Chicago Booth School of Business since 2007; Director, Carlson Inc. (private global hospitalities and travel company) since 2015; Managing Director — Investment Banking, JP Morgan Chase & Co. (broker-dealer) 2002-2007.	12	None.

Maureen M. Culhane, 66, Trustee	2007	Retired. Formerly, Vice President, Goldman Sachs Asset Management, L.P. (investment adviser), 2005-2007; Vice President (Consultant) — Strategic Relationship Management, Goldman, Sachs & Co., 1999-2005.	12	None.

Margaret M. Eisen, 61, Trustee	2002	Trustee, Smith College since 2012; Chief Investment Officer, EAM International LLC (corporate finance and asset management), 2003-2013; Managing Director, CFA Institute, 2005-2008.	12	Burnham Investors Trust (3 series).


Committee	Members	Function	Number of Meetings in 2014
Compliance	Margaret M. Eisen (chair) Maureen M. Culhane Thomas M. Goldstein 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 audit matters); oversees compliance and risk management by the Funds’ service providers, including with respect to the Transfer Agent’s sub-transfer agent compliance program; and carries out the provisions of its charter.	4

Contract	David J. Rudis (chair) Laura M. Born Maureen M. Culhane Margaret M. Eisen Charles R. Phillips	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 affiliated and third party service providers; and carries out the provisions of its charter.	9

Executive	Laura M. Born (chair) Steven N. Kaplan P. Zachary Egan	Exercises powers of the Board during intervals between meetings of the Board, with certain exceptions.	0

Governance	Steven N. Kaplan (chair) Laura M. Born Margaret M. Eisen	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; monitors the performance of the CCO and makes recommendations to the Board regarding the selection and compensation of the CCO; 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; and carries out the provisions of its charter.	5


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⁽¹⁾	$	125,552	$	52,803	$	10,263	$	2,214	$	4,979	$	8,226	$	298	$	3,120	$	207,454	$	219,200
Michelle L. Collins⁽²⁾	$	67,182	$	27,841	$	5,481	$	1,179	$	2,658	$	4,346	$	157	$	1,612	$	110,458	$	116,700
Maureen M. Culhane	$	77,857	$	32,787	$	6,373	$	1,372	$	3,087	$	5,108	$	184	$	1,941	$	128,709	$	136,000
Margaret M. Eisen	$	105,707	$	44,906	$	8,656	$	1,867	$	4,194	$	6,980	$	256	$	2,701	$	175,266	$	185,200
Thomas M. Goldstein⁽³⁾	$	12,663	$	5,769	$	1,030	$	232	$	501	$	871	$	36	$	381	$	21,483	$	22,700
John C. Heaton⁽⁴⁾	$	78,269	$	33,265	$	6,411	$	1,387	$	3,108	$	5,176	$	188	$	1,994	$	129,799	$	137,160
Steven N. Kaplan⁽⁵⁾	$	77,281	$	32,704	$	6,315	$	1,369	$	3,067	$	5,087	$	185	$	1,947	$	127,955	$	135,200
Charles R. Phillips⁽⁶⁾		—		—		—		—		—		—		—		—		—		—
David J. Rudis⁽⁷⁾	$	101,745	$	43,051	$	8,325	$	1,795	$	4,030	$	6,689	$	247	$	2,577	$	168,459	$	178,000
David B. Small⁽⁸⁾	$	66,452	$	27,930	$	5,438	$	1,170	$	2,633	$	4,352	$	157	$	1,651	$	109,783	$	116,000


Name and Age at March 31, 2015	Position with the Trust	Year First Appointed or Elected to Office	Principal Occupation(s) During the Past Five Years
Alan G. Berkshire, 54⁽¹⁾	Vice President	2015	Chief Operating Officer, CWAM since April 2015. Formerly, Independent Director, ValueQuest India Moat Fund Limited (Mauritius), April 2014-March 2015; President — North America, Religare Global Asset Management, Inc., June 2011-November 2013; Partner, Estancia Capital Management LLC, September 2009-June 2011.

Robert A. Chalupnik, 49	Vice President	2011	Portfolio manager and/or analyst, CWAM or its predecessors since 2000; Vice President, Columbia Acorn Trust and Wanger Advisors Trust since 2011.

Michael G. Clarke, 45	Assistant Treasurer	2004	Vice President — Mutual Fund Administration, Columbia Management since May 2010; Managing Director of Fund Administration, Columbia Management Advisors, LLC, September 2004-April 2010; Senior officer of Columbia Funds and affiliated funds since 2002.


Fund	Fiscal Year Ended December 31, 2014		Fiscal Year Ended December 31, 2013		Fiscal Year Ended December 31, 2012
Columbia Acorn Fund	$	8,390,000	$	7,029,000	$	6,518,000
Columbia Acorn International	$	6,566,000	$	9,141,000	$	5,042,000
Columbia Acorn USA	$	533,000	$	697,000	$	799,000
Columbia Acorn Select	$	337,000	$	624,000	$	1,139,000
Columbia Acorn International Select	$	566,000	$	661,000	$	474,000
Columbia Acorn European Fund	$	88,000	$	30,000	$	3,000
Columbia Acorn Emerging Markets Fund	$	853,000	$	798,000	$	13,000
Columbia Thermostat Fund		—		—		—


	Directed Transactions		Directed Commissions
Columbia Acorn Fund	$	5,513,402,000	$	4,041,000
Columbia Acorn International	$	2,092,840,000	$	2,884,000
Columbia Acorn USA	$	367,895,000	$	249,000
Columbia Acorn Select	$	236,105,000	$	179,000
Columbia Acorn International Select	$	222,701,000	$	277,000
Columbia Acorn European Fund	$	47,624,000	$	51,000
Columbia Acorn Emerging Markets Fund	$	230,659,000	$	393,000
Columbia Thermostat Fund		—		—


	Broker-Dealer		Dollar Amount of Securities Held
Columbia Acorn Fund		Eaton Vance Corp.	$	134,393,982


*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 • Bank of America, N.A. • Cetera Financial Group • Citigroup Global Markets Inc./Citibank • Commonwealth Financial Network • Great-West • First Clearing, LLC • Investacorp • J.J.B. Hilliard, W.L. Lyons, Inc. • Lincoln Financial Advisors Corp. • Linsco/Private Ledger Corp. • Morgan Stanley Smith Barney • Merrill Lynch, Pierce, Fenner & Smith Incorporated		• Northwestern Mutual Investment Services • Oppenheimer • PNC Investments • Raymond James & Associates, Inc. • Raymond James Financial Services, Inc. • RBC Capital Markets • Securities America • Triad Advisors • UBS Financial Services Inc. • US Bancorp Investments, Inc. • Wells Fargo Advisors, LLC • Wells Fargo Advisors Financial Network, LLC • Vanguard Marketing Corp


	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


Fund	Total Capital Loss Carryover		Amount Expiring in								Amount Not Expiring
Fund	Total Capital Loss Carryover		2015		2016		2017		2018		Short term		Long term
Columbia Acorn Fund		—		—		—		—		—		—		—
Columbia Acorn International	$	32,978,592	$	2,521,892	$	30,456,700		—		—		—		—
Columbia Acorn USA		—		—		—		—		—		—		—
Columbia Acorn Select		—		—		—		—		—		—		—
Columbia Acorn International Select		—		—		—		—		—		—		—
Columbia Acorn European Fund	$	2,338,404		—		—		—		—	$	2,338,404		—
Columbia Acorn Emerging Markets Fund	$	14,671,234		—		—		—		—	$	14,671,234		—
Columbia Thermostat Fund		—		—		—		—		—		—		—


	Approximate Percentage of Columbia Acorn European Fund
Charles P. McQuaid		1.0	%
P. Zachary Egan		1.2	%
Andreas Waldburg-Wolfegg		1.3	%
Steven Kusmierczak		1.3	%
Matthew S. Szafranski		1.3	%