N-30B-2 1 a15-6875_1n30b2.htm N-30B-2

FIRST QUARTER REPORT

March 31, 2015

COLUMBIA ACORN FAMILY OF FUNDS

Class A, B, C, I, R, R4, R5, Y and Z Shares
Managed by Columbia Wanger Asset Management, LLC

Columbia Acorn® Fund

Columbia Acorn International®

Columbia Acorn USA®

Columbia Acorn International Select^SM

Columbia Acorn Select^SM

Columbia Thermostat Fund^SM

Columbia Acorn Emerging Markets Fund^SM

Columbia Acorn European Fund^SM

COLUMBIA ACORN FAMILY OF FUNDS

OUR NEW LOOK

On March 30, 2015, Columbia Management (an affiliate of Columbia Wanger) and its U.K.-based affiliate, Threadneedle Investments, rebranded to Columbia Threadneedle Investments. The new global brand represents the combined capabilities, resources and reach of the global group and offers investors the best of both firms. As a result of this new brand, we have adopted a new logo and colors, which are reflected in this report. To learn more, we encourage you to visit our website at our new address: columbiathreadneedle.com/us.

NET ASSET VALUE PER SHARE as of 3/31/15

	Columbia Acorn® Fund		Columbia Acorn International®		Columbia Acorn USA®		Columbia Acorn International Select^SM		Columbia Acorn Select^SM		Columbia Thermostat Fund^SM		Columbia Acorn Emerging Markets Fund^SM		Columbia Acorn European Fund^SM
Class A	$	31.48	$	43.46	$	30.61	$	22.35	$	21.61	$	15.07	$	12.61	$	14.96
Class B	$	27.51	$	42.02	$	26.47	$	20.95	$	18.49	$	15.16		N/A		N/A
Class C	$	26.88	$	41.84	$	26.20	$	20.80	$	18.15	$	15.15	$	12.52	$	14.75
Class I	$	33.31	$	43.59	$	32.80	$	22.62	$	23.03		N/A	$	12.65	$	14.96
Class R		N/A	$	43.41		N/A		N/A		N/A		N/A		N/A		N/A
Class R4	$	33.80	$	43.84	$	33.33	$	22.79	$	23.39	$	14.96	$	12.72	$	15.03
Class R5	$	33.84	$	43.52	$	33.35	$	22.77	$	23.43	$	14.97	$	12.71	$	15.11
Class Y	$	33.91	$	43.86	$	33.44	$	22.76	$	23.52	$	14.96	$	12.60		N/A
Class Z	$	33.22	$	43.54	$	32.62	$	22.63	$	22.91	$	14.89	$	12.64	$	14.97

Class I shares are available only to the Columbia funds, such as Columbia Thermostat Fund, and are not available to individual investors. Class R, R4, R5, Y and Z shares are sold at net asset value and have limited eligibility. Please see the Funds' prospectuses for details. The Columbia Acorn Family of Funds offer multiple share classes, not all necessarily available through all firms, and the share class ratings may vary. Contact us for details.

The views expressed in the report commentaries reflect the current views of the respective authors. These views are not guarantees of future performance and involve certain risks, uncertainties and assumptions that are difficult to predict, so actual outcomes and results may differ significantly from the views expressed. These views are subject to change at any time based upon economic, market or other conditions and the respective authors disclaim any responsibility to update such views. These views may not be relied upon as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied upon as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to a specific company's securities should not be construed as a recommendation or investment advice and there can be no assurance that as of the date of publication of this report, the securities mentioned in each Fund's portfolio are still held or that the securities sold have not been repurchased.

Acorn®, Acorn USA® and Acorn International® are service marks owned and registered by Columbia Acorn Trust.

PRESIDENT'S MESSAGE

April 1, 2015 marked my one-year anniversary as head of Columbia Wanger Asset Management, LLC (Columbia Wanger). I have spent this year focused on our investment operations and processes, building on my 15 years as an international analyst and portfolio manager with the firm. In particular, I have spent considerable time analyzing the investment processes followed by our domestic Acorn Funds. As shareholders are doubtless aware, our domestic products have generated strong absolute returns over the last three years, benefiting from buoyant U.S. markets, but returns relative to benchmarks and peers have been unsatisfactory.

This has led to important enhancements to portfolio management. Effective May 1, 2015, we have added portfolio managers to several of our Funds. Most notably, Fritz Kaegi and I have become portfolio managers of Columbia Acorn Fund and, initially, we will work alongside current managers, David Frank and Robert Mohn. After 23 years at Columbia Wanger, Rob has announced his plans to retire in the fourth quarter of this year. Rob was among the first analysts Ralph Wanger hired after founding the firm in 1992, and we thank him for his years of outstanding service to Columbia Wanger and Fund shareholders. After Rob's departure, David, Fritz and I will continue to co-manage Columbia Acorn Fund. Fritz and David have long tenures at Columbia Wanger, with excellent track records as investment professionals. We are also taking steps to improve our investment process, outlined in a discussion of Columbia Acorn Fund's performance that follows (see Page 3). We believe these steps will bring performance more in line with our own high standards and historical record of performance, to the benefit of Fund shareholders. With respect to our other Funds, Matt Szafranski has been named a co-portfolio manager of Columbia Acorn Select; Andreas Waldburg-Wolfegg has become a co-portfolio manager of Columbia Acorn International Select; and Satoshi Matsunaga has been added as a co-portfolio manager of Columbia Acorn Emerging Markets Fund. These individuals will work with the current managers of the Funds. Also effective May 1, 2015, I am no longer involved in the day-to-day management of Columbia Acorn Emerging Markets Fund.

We at Columbia Wanger believe that we have an investment strategy and process capable of generating excess returns versus benchmarks and peers. This approach, initially pioneered by Ralph Wanger and Chuck McQuaid in the 1970s, puts an emphasis on: (1) identifying and investing in quality business models at reasonable prices; (2) seizing

upon long-term changes in society and specific industries that portend above-average prospects for growth; and (3) recognizing when one is "paid to take risk," while limiting the impact of that risk on the overall portfolio through careful consideration of position size. A central element of this process has been lively internal debate about the characteristics and merits of individual investments, emphasizing the logic behind the discrete components of the investment case. This scrutinizing of business models as well as the likely effects of industry trends sometimes requires thick skin among participants, but generally leads to better decision-making.

My highest priority as a leader of this organization is to build on our culture of active debate in the investment process in order to foster high conviction in all of our portfolios. The aforementioned personnel changes are designed to help achieve this. In the case of Columbia Acorn Fund, we have added experienced international portfolio managers to a domestic fund that is increasingly being shaped by global trends, and where we believe there is an opportunity to improve both stock selection and portfolio construction. With Columbia Acorn Select and Columbia Acorn International Select, we expect that increased debate between two portfolio managers, who have together agreed and articulated the specific investment strategies these concentrated portfolios will execute, will drive a more consistent outcome. This change will also support Columbia Acorn International Select's ongoing repositioning as a more mid-cap oriented strategy that generally invests in businesses with market capitalizations higher than those appropriate for Columbia Acorn International. To promote more effective portfolio monitoring, and to provide managers with more quantitative clarity about style biases and other risks embedded in portfolios constructed on a bottom-up basis, we have also introduced a new Head of Investment Performance and Risk position.

The portfolio managers and analysts at Columbia Wanger are invested with you in the Columbia Acorn Funds. This, and the excitement of working within a tradition that achieved legendary results over more than four decades, are powerful motivators for extending that track record. Thank you for your investment in the Columbia Acorn Funds.

P. Zachary Egan

President and International Chief Investment Officer
Columbia Wanger Asset Management, LLC

There is no guarantee that investment objectives will be achieved or that any particular investment will be profitable.

COLUMBIA ACORN FAMILY OF FUNDS

TABLE OF CONTENTS

Addressing Columbia Acorn Fund Performance and Process					3
Descriptions of Indexes					5
Share Class Performance					6
Fund Performance vs. Benchmarks					7
Columbia Acorn® Fund
In a Nutshell					8
At a Glance					9
Major Portfolio Changes					24
Statement of Investments					27
Columbia Acorn International®
In a Nutshell					10
At a Glance					11
Major Portfolio Changes					36
Statement of Investments					39
Portfolio Diversification					47
Columbia Acorn USA®
In a Nutshell					12
At a Glance					13
Major Portfolio Changes					48
Statement of Investments					50
Columbia Acorn International Select^SM
In a Nutshell					14
At a Glance					15

Major Portfolio Changes					55
Statement of Investments					56
Portfolio Diversification					60
Columbia Acorn Select^SM
In a Nutshell					16
At a Glance					17
Major Portfolio Changes					61
Statement of Investments					62
Columbia Thermostat Fund^SM
In a Nutshell					18
At a Glance					19
Statement of Investments					67
Columbia Acorn Emerging Markets Fund^SM
In a Nutshell					20
At a Glance					21
Major Portfolio Changes					69
Statement of Investments					70
Portfolio Diversification					75
Columbia Acorn European Fund^SM
In a Nutshell					22
At a Glance					23
Major Portfolio Changes					76
Statement of Investments					78
Portfolio Diversification					82
Columbia Acorn Family of Funds^SM
Expense Information					83

A COMMENT ON TRADING VOLUMES

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 Funds. This is particularly so because the Funds focus on small- and mid-cap companies that usually have lower trading volumes and often take sizeable positions in portfolio companies. As a result of lower trading volumes, it may take longer to buy or sell securities, which can exacerbate a Fund's exposure to volatile markets. A Fund may also be limited in its ability to execute favorable trades in portfolio securities in response to changes in company prices and fundamentals. If a 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.

ADDRESSING COLUMBIA ACORN FUND PERFORMANCE
AND PROCESS


Robert A. Mohn Co-Portfolio Manager				P. Zachary Egan Co-Portfolio Manager

Fritz Kaegi Co-Portfolio Manager				David L. Frank Co-Portfolio Manager

After decades of outperformance, Columbia Acorn Fund has more recently joined the ranks of actively-managed mutual funds struggling to beat their benchmarks. We are not happy about it and are determined to reverse this course. As described in detail below, after a process of intense review, we have decisively addressed certain key practices in order to reinvigorate the Columbia Wanger process, which has served the Funds well for many years. The steps we have taken include: reducing the number of stocks in the portfolio, instituting minimum position sizes, modestly increasing concentration within our top holdings and reducing macroeconomic exposure where possible. We have also reinforced our investment and support teams.

Columbia Acorn Fund has historically driven investment results predominantly through stock selection, consistent with our investment style of growth-at-a-reasonable-price (GARP). GARP has been out of style in prior performance periods, which hurt the Fund's relative investment performance, but it has become apparent from ongoing results that this was only part of the Fund's underperformance story. As we evaluated Columbia Acorn Fund's shortfall versus its benchmark, the Russell 2500 Index, in the buoyant market environment of the last three years, we could see that underperformance has been significantly driven by stock selection. Stock selection is about identifying individual stocks whose fundamental characteristics or attractive valuations suggest they are poised to outperform related peers within an industry group or some other category. Stock selection also involves allocating capital proportionate to anticipated risk-adjusted returns. Successful stock selection requires getting three things right: (1) picking more winners than losers (a good "hit rate"); (2) sizing the positions correctly so that the most promising ideas garner the most capital; and (3) monitoring macroeconomic exposures so that good stock selection is not canceled out by unexpected economic or market shifts.

High hit rates and correct position-sizing require in-depth, fundamental understanding of individual companies. This in turn requires significant analyst resources and time. While we believe we operate with unrivalled analyst resources, in hindsight these analyst resources may have been spread across too many individual holdings and often were narrowly focused on sub-industry groups. At times, this undermined the formation of the scarcest factor in investment management—conviction—and made capital allocation difficult, as it is hard to assess relative value across a portfolio with a great number of positions, some very small, spread across a wide range of sub-industry groups.

We believe we can improve the performance of Columbia Acorn Fund going forward and have taken the following steps relating to stock selection and portfolio construction:

• Number of positions in portfolio. The number of portfolio positions has been reduced significantly in the first quarter from 277 to 205, with most of the smaller positions having been sold or, where our level of conviction is high, increased. After quarter end, the Fund held fewer than 200 positions. By contrast, in the 2010-2012 period, the Fund closed each year with over 360 positions.

• Position sizes. We are instituting minimum position sizes (with carefully delineated exceptions) and more aggressively aligning position sizes with our analysts' expected returns. As an outcome of the more tightly constructed portfolio, we expect a higher portfolio turnover (albeit one that is still substantially below industry averages).

• Concentration. We are modestly increasing concentration within our top 10 holdings. This measure stood at 18.3% at quarter end, the highest it has been since 2002. We are now at a level of concentration comparable to the years when the Fund posted strong outperformance.

• Reinforcing our investment and support teams. In addition to the portfolio manager changes outlined in Zach Egan's letter on Page 1, we are adding analysts to our coverage of domestic stocks. We have also created a Head of Investment Performance and Risk position and hired a new Chief Operating Officer, which gives us enhanced analytical and oversight resources and

increases the investment team's ability to focus on stock picking and improving performance.

In terms of macroeconomic exposures, we have made one major change to Columbia Acorn Fund's asset allocation: going forward we expect to hold a much more modest stake in non-U.S. equities. At the end of the quarter, the foreign weight was 2.2%, whereas one year earlier it was 7.0%. In the past, foreign stock exposure has been as high as 15%. This practice has introduced a level of uncertainty into Fund performance, since variables beyond company fundamentals, such as unhedged currency exposure or central bank policies, inevitably entered the equation. While this exposure has resulted in meaningful positive contributions to performance in the past, the Fund's foreign weight can explain over one-quarter of underperformance versus benchmark in the three-year period ended March 31, 2015. We are also mindful that the investment industry has evolved since Columbia Acorn Fund first adopted this practice, and now generally prefers more focused and predictable strategies. The reduced foreign exposure going forward should also make it easier for shareholders to assess their economic exposure to foreign markets and currency moves.

Generally, Columbia Acorn Fund portfolio managers will not make top-down "macro" calls. The times when we feel like we have a special, contrarian perspective on a significant opportunity and make such calls will be infrequent. While not central to our process, the monitoring of macroeconomic exposure does occasionally yield insights that shape Columbia Acorn Fund's portfolio construction. For example, in the past the monitoring of credit spreads helped us recognize "paid to take risk" market environments when we would orient the portfolio toward companies with balance sheet risk, which would outperform during the subsequent mean reversion of credit spreads.

This brings us to the Fund's current positioning. Our largest sector deviation from the benchmark is in industrials. U.S. industrial companies offer a wide choice of potential investments, many of which have the attractive ability to not only reinvest in their businesses at good rates of return, but also to sell their products to the entire world. We believe these sorts of companies play to our analytical strengths. On the other hand, in certain pockets of the market, we perceive an extreme valuation environment where investors are "not paid to take risk." Specifically, unprecedentedly low interest rates have greatly aided industries where we have traditionally placed less capital, most

notably high-yielding utilities and real estate investment trusts (REITs). We expect to continue this underweight. The critical characteristic of REITs is that they pay out nearly all of the cash flows generated by their assets, and therefore have little ability to reinvest in their business without raising new capital. The bottom-up, company-by-company work done by our analysts indicates that real estate securities at today's prices offer little compensation for the benefits and risks they bring.

We think the Fund's current sector positioning is appropriate for an environment where interest rates are very low and earnings multiples are generally high. In an environment like this, companies that have the ability to re-invest in their businesses at good rates of return deserve some premium, while the market already has priced in most of the value for companies with little ability to re-invest, such as REITs and utilities. We expect these sector weightings, along with the recent changes relating to stock selection and portfolio construction discussed above, will lift Fund performance over the medium and long term.

We look forward to continuing this conversation with you in coming quarters. Thank you for your support and investment in Columbia Acorn Fund.

Robert A. Mohn

P. Zachary Egan

Fritz Kaegi

David L. Frank

COLUMBIA ACORN FAMILY OF FUNDS

DESCRIPTIONS OF INDEXES INCLUDED IN THIS REPORT

• 50/50 Blended Benchmark, established by the Fund's investment manager, is an equally weighted custom composite of Columbia Thermostat 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.

• 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.

• 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.

• Lipper Indexes are composed of the 10 or 30 largest funds in the Lipper investment objective grouping. Lipper Mid-Cap Growth Funds Index, 30 largest mid-cap growth funds, including Columbia Acorn Fund; Lipper International Small/Mid Growth Funds Index, 10 largest non-U.S. small/mid growth funds, including Columbia Acorn International and Columbia Acorn International Select; Lipper Small-Cap Growth Funds Index, 30 largest small-cap growth funds, including Columbia Acorn USA; Lipper Mid-Cap Core Funds Index, 30 largest mid-cap core funds; Lipper Flexible Portfolio Funds Index, an equal-weighted index of the 30 largest mutual funds within the Flexible Portfolio fund classification, as defined by Lipper; Lipper Emerging Markets Index, 30 largest emerging markets funds; Lipper European Region Index, 10 largest European funds.

• MSCI Europe, Australasia and Far East (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 returns of the MSCI EAFE Index (Net) are presented net of the withholding tax rate applicable to foreign non-resident institutional investors in the foreign companies included in the index who do not benefit from double taxation treaties.

• MSCI Emerging Markets Small Cap Index (Net), a widely recognized international benchmark, is a free float-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 MSCI Emerging Markets Small Cap Index (Net) currently consists of the following emerging market country indexes: Brazil, Chile, China, Colombia, Czech Republic, Egypt, Hungary, India, Indonesia, Korea, Malaysia, Mexico, Morocco, Peru, Philippines, Poland, Qatar, Russia, South Africa, Taiwan, Thailand, Turkey and United Arab Emirates.

• 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.

• 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.

• Standard & Poor's (S&P) 500® Index tracks the performance of 500 widely held, large-capitalization U.S. stocks.

• S&P MidCap 400® Index is a market value-weighted index that tracks the performance of 400 mid-cap U.S. companies.

• S&P Developed Ex-U.S. Between $2B and $10B® Index is a subset of the broad market selected by the index sponsor that represents the mid-cap developed market, excluding the United States.

• S&P Emerging Markets Between $500M and $5B® Index represents 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 index currently consists of the following emerging market country indexes: Brazil, Chile, China, Colombia, Czech Republic, Egypt, Hungary, India, Indonesia, Malaysia, Mexico, Morocco, Peru, Philippines, Poland, Russia, South Africa, Taiwan, Thailand and Turkey.

• S&P Europe Between $500M and $5B® Index represents 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 index consists of the following European countries: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

• S&P Global Ex-U.S. SmallCap® Index consists of the bottom 20% of institutionally investable capital of developed and emerging countries, excluding the United States.

• S&P Global Ex-U.S. Between $500M and $5B® 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.

Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.

COLUMBIA ACORN FAMILY OF FUNDS

SHARE CLASS PERFORMANCE Average Annual Total Returns through 3/31/15

	Class A						Class B						Class C						Class I			Class R			Class R4			Class R5			Class Y			Class Z
	Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge			Without Sales Charge			With Sales Charge
Columbia Acorn® Fund
Year to date*		3.89	%		-2.08	%		3.69	%		-1.31	%		3.70	%		2.70	%		4.00	%		N/A			3.97	%		3.96	%		3.99	%		3.97	%
1 year		4.55	%		-1.46	%		3.79	%		-0.49	%		3.80	%		2.95	%		4.94	%		N/A			4.81	%		4.89	%		4.94	%		4.86	%
5 years		12.31	%		10.98	%		11.63	%		11.37	%		11.49	%		11.49	%		12.71	%		N/A			12.62	%		12.66	%		12.69	%		12.64	%
10 years		8.64	%		8.00	%		7.97	%		7.97	%		7.81	%		7.81	%		8.99	%		N/A			8.94	%		8.96	%		8.97	%		8.95	%
Columbia Acorn International®
Year to date*		4.27	%		-1.72	%		4.06	%		-0.94	%		4.08	%		3.08	%		4.38	%		4.18	%		4.33	%		4.34	%		4.38	%		4.34	%
1 year		-1.62	%		-7.28	%		-2.37	%		-6.97	%		-2.33	%		-3.26	%		-1.21	%		-2.01	%		-1.41	%		-1.30	%		-1.24	%		-1.33	%
5 years		8.29	%		7.02	%		7.53	%		7.23	%		7.48	%		7.48	%		8.72	%		7.93	%		8.61	%		8.66	%		8.68	%		8.64	%
10 years		8.71	%		8.07	%		7.98	%		7.98	%		7.88	%		7.88	%		9.11	%		8.37	%		9.05	%		9.07	%		9.09	%		9.07	%
Columbia Acorn USA®
Year to date*		5.08	%		-0.97	%		4.75	%		-0.25	%		4.88	%		3.88	%		5.16	%		N/A			5.14	%		5.17	%		5.16	%		5.12	%
1 year		7.97	%		1.75	%		6.85	%		2.55	%		7.23	%		6.37	%		8.40	%		N/A			8.24	%		8.33	%		8.37	%		8.22	%
5 years		13.24	%		11.91	%		12.40	%		12.15	%		12.44	%		12.44	%		13.67	%		N/A			13.56	%		13.59	%		13.61	%		13.54	%
10 years		7.86	%		7.23	%		7.11	%		7.11	%		7.06	%		7.06	%		8.22	%		N/A			8.17	%		8.18	%		8.19	%		8.16	%
Columbia Acorn International Select^SM
Year to date*		1.41	%		-4.41	%		1.26	%		-3.74	%		1.27	%		0.27	%		1.48	%		N/A			1.51	%		1.52	%		1.52	%		1.48	%
1 year		-8.44	%		-13.70	%		-9.05	%		-13.04	%		-9.14	%		-9.93	%		-8.15	%		N/A			-8.17	%		-8.12	%		-8.09	%		-8.18	%
5 years		7.13	%		5.87	%		6.45	%		6.16	%		6.30	%		6.30	%		7.55	%		N/A			7.47	%		7.50	%		7.52	%		7.49	%
10 years		7.41	%		6.78	%		6.72	%		6.72	%		6.57	%		6.57	%		7.79	%		N/A			7.75	%		7.76	%		7.77	%		7.75	%
Columbia Acorn Select^SM
Year to date*		2.76	%		-3.14	%		2.55	%		-2.45	%		2.60	%		1.60	%		2.90	%		N/A			2.81	%		2.85	%		2.89	%		2.83	%
1 year		5.40	%		-0.64	%		4.58	%		0.50	%		4.71	%		3.90	%		5.82	%		N/A			5.66	%		5.77	%		5.84	%		5.72	%
5 years		9.06	%		7.78	%		8.33	%		8.09	%		8.26	%		8.26	%		9.49	%		N/A			9.36	%		9.40	%		9.43	%		9.38	%
10 years		7.91	%		7.27	%		7.18	%		7.18	%		7.08	%		7.08	%		8.27	%		N/A			8.21	%		8.23	%		8.24	%		8.22	%
Columbia Thermostat Fund^SM
Year to date*		1.41	%		-4.44	%		1.27	%		-3.73	%		1.27	%		0.27	%		N/A			N/A			1.49	%		1.49	%		1.49	%		1.50	%
1 year		4.85	%		-1.20	%		4.31	%		-0.69	%		4.06	%		3.06	%		N/A			N/A			5.08	%		5.09	%		5.15	%		5.11	%
5 years		9.05	%		7.76	%		8.51	%		8.22	%		8.25	%		8.25	%		N/A			N/A			9.33	%		9.34	%		9.37	%		9.33	%
10 years		6.56	%		5.93	%		6.01	%		6.01	%		5.77	%		5.77	%		N/A			N/A			6.83	%		6.84	%		6.85	%		6.83	%
Columbia Acorn Emerging Markets Fund^SM
Year to date*		-0.86	%		-6.59	%		N/A			N/A			-1.03	%		-2.02	%		-0.78	%		N/A			-0.86	%		-0.86	%		-0.87	%		-0.78	%
1 year		-4.17	%		-9.70	%		N/A			N/A			-4.94	%		-5.89	%		-3.90	%		N/A			-3.93	%		-3.91	%		-3.92	%		-3.94	%
Life of Fund		7.17	%		5.43	%		N/A			N/A			6.41	%		6.41	%		7.58	%		N/A			7.52	%		7.53	%		7.54	%		7.47	%
Columbia Acorn European Fund^SM
Year to date*		4.32	%		-1.64	%		N/A			N/A			4.17	%		3.17	%		4.40	%		N/A			4.37	%		4.42	%		N/A			4.39	%
1 year		-5.23	%		-10.67	%		N/A			N/A			-5.96	%		-6.90	%		-5.00	%		N/A			-4.96	%		-5.01	%		N/A			-4.98	%
Life of Fund		12.53	%		10.71	%		N/A			N/A			11.72	%		11.72	%		12.86	%		N/A			12.83	%		12.83	%		N/A			12.83	%

*Not annualized.

Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class B shares are shown with and without the applicable contingent deferred sales charge (CDSC) of 5.00% in the first year, declining to 1.00% in the sixth year and eliminated thereafter. Returns for Class C shares are shown with and without the maximum CDSC of 1.00% for the first year after purchase. The Funds' other classes are not subject to sales charges and have limited eligibility. Please see the Funds' prospectuses for details. Performance for different share classes will vary based on differences in sales charges and certain fees associated with each class.

All results shown assume reinvestment of distributions during the period. Returns do not reflect the deduction of taxes that a shareholder may pay on Fund distributions or on the redemption of Fund shares. Performance results may reflect the effect of any fee waivers or reimbursements of Fund expenses by the investment manager and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower. Please see Page 83 of this report for information on contractual fee waiver and expense reimbursement agreements in place on March 31, 2015, for Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund and voluntary fee waiver and expense reimbursement arrangements in place for Columbia Acorn International, Columbia Acorn International Select and Columbia Acorn Select.

The performance information shown represents past performance and is not a guarantee of future results. The investment return and principal value of your investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. You may obtain performance information current to the most recent month-end by contacting your financial intermediary, visiting columbiathreadneedle.com/us or calling 800.922.6769.

The returns shown include the returns of each Fund's Class Z shares, each Fund's oldest share class, in cases where the inception date of the Fund is earlier than the inception date of the particular share class or where a period shown dates to before the inception date of the share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Continued on Page 7.

FUND PERFORMANCE VS. BENCHMARKS Class Z Average Annual Total Returns through 3/31/15

Class Z Shares	1st quarter*			1 year			5 years			10 years			Life of Fund
Columbia Acorn® Fund (ACRNX) (6/10/70)		3.97	%		4.86	%		12.64	%		8.95	%		14.60	%
Russell 2500 Index		5.17	%		10.07	%		15.48	%		9.62	%		N/A
S&P 500 Index**		0.95	%		12.73	%		14.47	%		8.01	%		11.01	%
Russell 2000 Index		4.32	%		8.21	%		14.57	%		8.82	%		N/A
Lipper Mid-Cap Growth Funds Index		5.07	%		11.85	%		14.26	%		9.86	%		N/A
Columbia Acorn International® (ACINX) (9/23/92)		4.34	%		-1.33	%		8.64	%		9.07	%		10.96	%
S&P Global Ex-U.S. Between $500M and $5B Index		4.92	%		0.85	%		7.21	%		7.93	%		8.44	%
S&P Global Ex-U.S. SmallCap Index		3.70	%		-2.69	%		7.27	%		7.32	%		7.84	%
MSCI EAFE Index (Net)		4.88	%		-0.92	%		6.16	%		4.95	%		6.13	%
Lipper International Small/Mid Growth Funds Index		5.58	%		-2.54	%		9.99	%		8.52	%		N/A
Columbia Acorn USA® (AUSAX) (9/4/96)		5.12	%		8.22	%		13.54	%		8.16	%		10.96	%
Russell 2000 Index		4.32	%		8.21	%		14.57	%		8.82	%		8.82	%
Lipper Small-Cap Growth Funds Index		5.74	%		8.34	%		14.73	%		8.55	%		7.44	%
Columbia Acorn Int'l Select^SM (ACFFX) (11/23/98)		1.48	%		-8.18	%		7.49	%		7.75	%		8.75	%
S&P Developed Ex-U.S. Between $2B and $10B Index		5.61	%		1.12	%		7.85	%		6.72	%		7.66	%
MSCI EAFE Index (Net)		4.88	%		-0.92	%		6.16	%		4.95	%		4.39	%
Lipper International Small/Mid Growth Funds Index		5.58	%		-2.54	%		9.99	%		8.52	%		10.23	%
Columbia Acorn Select^SM (ACTWX) (11/23/98)		2.83	%		5.72	%		9.38	%		8.22	%		10.31	%
S&P MidCap 400 Index		5.31	%		12.19	%		15.72	%		10.32	%		10.79	%
S&P 500 Index**		0.95	%		12.73	%		14.47	%		8.01	%		5.53	%
Lipper Mid-Cap Core Funds Index		4.03	%		10.12	%		14.02	%		9.06	%		9.33	%
Columbia Thermostat Fund^SM (COTZX) (9/25/02)		1.50	%		5.11	%		9.33	%		6.83	%		7.95	%
S&P 500 Index		0.95	%		12.73	%		14.47	%		8.01	%		9.90	%
Barclays U.S. Aggregate Bond Index		1.61	%		5.72	%		4.41	%		4.93	%		4.71	%
Lipper Flexible Portfolio Funds Index		1.48	%		3.83	%		8.28	%		6.43	%		7.99	%
50/50 Blended Benchmark		1.37	%		9.30	%		9.60	%		6.76	%		7.57	%
Columbia Acorn Emerging Markets Fund^SM (CEFZX) (8/19/11)		-0.78	%		-3.94	%		—			—			7.47	%
S&P Emerging Markets Between $500M and $5B Index		1.86	%		3.07	%		—			—			3.61	%
MSCI Emerging Markets Small Cap Index (Net)		3.59	%		1.06	%		—			—			2.07	%
Lipper Emerging Markets Index		1.05	%		-1.21	%		—			—			2.32	%
Columbia Acorn European Fund^SM (CAEZX) (8/19/11)		4.39	%		-4.98	%		—			—			12.83	%
S&P Europe Between $500M and $5B Index		5.32	%		-6.11	%		—			—			14.42	%
Euromoney Smaller European Companies (inc. UK) Index		4.42	%		-10.35	%		—			—			12.20	%
Lipper European Region Index		4.45	%		-4.15	%		—			—			12.58	%

The inception dates for Class A, B and C shares (if offered) are as follows: Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select, 10/16/00; Columbia Thermostat Fund, 3/3/03; Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 8/19/11. The inception dates for Class I shares are as follows: Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select, 9/27/10; Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 8/19/11. The inception date for Class R shares for Columbia Acorn International is 8/2/11. The inception date for Class R4, R5 and Y shares (if offered) is as follows: Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 11/8/12, except that Class Y shares of Columbia Acorn Emerging Markets Fund commenced operations on 6/13/13 and Class R4 shares of Columbia Acorn European Fund commenced operations on 6/25/14. The inception date for Class R5 shares of Columbia Acorn International is 8/2/11. The inception date for Class R4 and Y shares of Columbia Acorn International is 11/8/12. The inception date for Class Z shares is as follows: Columbia Acorn Fund, 6/10/70; Columbia Acorn International, 9/23/92; Columbia Acorn USA, 9/4/96; Columbia Acorn International Select and Columbia Acorn Select, 11/23/98; Columbia Thermostat Fund, 9/25/02; Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 8/19/11.

*Not annualized.

**Although the Fund typically invests in small- and mid-sized companies, the comparison to the S&P 500® Index is presented to show performance against a widely recognized market index over the life of the Fund.

Please see Page 5 for a description of the indexes listed above.

COLUMBIA ACORN® FUND

IN A NUTSHELL


Robert A. Mohn Lead Portfolio Manager				David L. Frank Co-Portfolio Manager

Performance data shown represents past performance and is not a guarantee of future results. The investment return and principal value will fluctuate so that shares, when redeemed, may be worth more or less than the original cost. Current performance may be lower or higher than the performance data shown. Please visit columbiathreadneedle.com/us for daily and most recent month-end performance updates.

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. Foreign investments subject the Fund to political, economic, market, social and other risks within a particular country, as well as to potential currency instabilities and less stringent financial and accounting standards generally applicable to U.S. issuers. Risks are enhanced for emerging market issuers. The Fund may invest significantly in issuers within a particular sector, which may be negatively affected by market, economic or other conditions, making the Fund more vulnerable to unfavorable developments in the sector.

Columbia Acorn Fund Class Z shares gained 3.97% in the first quarter of 2015. This compares to a 5.17% gain for the Fund's primary benchmark, the Russell 2500 Index. Relative returns were dampened by the weaker-than-benchmark performance of some of the Fund's industrial and consumer stocks.

Looking first at what assisted returns, Fund holdings in the biotechnology and pharmaceutical industries were strong absolute contributors for the quarter. Akorn, a manufacturer and distributor of specialty generic drugs, gained 29% as revenue jumped 168% over the prior year, aided by some significant generic drug price hikes. Biotech company Intercept Pharmaceuticals gained 82% in the first quarter on news that its drug to treat liver disease received a "breakthrough" designation, indicating that the FDA will work closely with the company to expedite the drug's approval. Orphan drug developer Ultragenyx Pharmaceutical gained 42% on continued steady progress in advancing its drug pipeline. Celldex Therapeutics, a biotech focusing on cancer drug development, gained 54% in the quarter following news of favorable data from a study for its brain cancer drug, Rintega.

Other winners in the quarter included SEI Investments, a mutual fund administrator and investment manager that enjoyed strong cash inflows into its actively managed strategies. Its stock was up 10% for the quarter. IPG Photonics, a manufacturer of fiber lasers, gained 24% on solid year-over-year revenue growth.

Weaker prices hurt energy service providers in the quarter. ShawCor, a Canadian provider of oil and gas pipeline products, declined 24%. Chicago Bridge & Iron, an engineering and construction services provider for liquefied natural gas and petrochemicals companies, and Hornbeck Offshore, a supply vessel operator in the Gulf of Mexico, were also down more than 20%. We opted to sell the Fund's position in Chicago Bridge & Iron. Down 15%, truck dealership Rush Enterprises (Class A) was also impacted by weaker energy prices, as 10% of its truck sales are to energy supply chain customers.

Additional losses resulted from the Fund's investments in car rental companies Avis Budget Group and Hertz, which fell 11% and 12%, respectively, on concerns over weaker than expected pricing. Hardwood flooring retailer Lumber Liquidators fell 56% in the quarter after the company received negative publicity. We opted to sell the Fund's position in the stock.

Small caps offered strong performance in the first quarter of the year, outpacing the 0.95% gain of the large-cap oriented S&P 500® Index. Ever mindful of valuation, we continue to seek what we believe to be well-run smaller companies that have the potential to thrive in the current economic environment and grow faster than their peers. We are also making adjustments to the Fund's portfolio to concentrate its holdings in our highest-conviction names. We believe these steps should improve the Fund's performance relative to the benchmark. For additional information on the steps that we are taking to address the relative underperformance of the Fund, please turn to Page 3 of this report.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

SEI Investments	2.3	%
Akorn	1.0
Avis Budget Group	1.0
IPG Photonics	0.9
Ultragenyx Pharmaceutical	0.7
Rush Enterprises*	0.6
Intercept Pharmaceuticals	0.5
Celldex Therapeutics	0.4
Hertz	0.4
ShawCor	0.4
Hornbeck Offshore	0.2

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

*The Fund is invested in Class A and Class B shares of this company.

COLUMBIA ACORN® FUND

AT A GLANCE

Total Net Assets of the Fund:
$14.1 billion

Performance data shown below represents past performance, does not guarantee future results, assumes reinvestment of dividends and distributions and does not reflect the deduction of taxes that a shareholder may pay on Fund distributions or the redemption of Fund shares. The investment return and principal value of an investment will fluctuate so that shares, when redeemed, may be worth more or less than their original cost. Current performance may be lower or higher than the performance data shown. Performance data reflects fee waivers or reimbursements of Fund expenses, if any; in their absence, performance results would have been lower. Indexes are unmanaged; their results do not reflect the effect of expenses or sales charges. Securities in the Fund may not match those in an index. Please visit columbiathreadneedle.com/us for performance data current to the most recent month-end.

The Growth of a $10,000 Investment in Columbia Acorn® Fund Class Z Shares

June 10, 1970 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period. A $10,000 investment in Columbia Acorn Fund at inception appreciated to $31,777 on December 31, 1978, the inception date of the Russell 2500 Index. For comparison with the Russell 2500 Index, we assigned the index the same value as the Fund at index inception. Although the Fund typically invests in small- and mid-sized companies, the comparison to the S&P 500 Index is presented to show performance against a widely recognized market index over the life of the Fund.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			5 years			10 years			Life of Fund
Class Z (6/10/70 inception)		3.97	%		4.86	%		12.64	%		8.95	%		14.60	%
Class A (10/16/00 inception)
without sales charge		3.89			4.55			12.31			8.64			14.23
with sales charge		-2.08			-1.46			10.98			8.00			14.08
Russell 2500 Index*		5.17			10.07			15.48			9.62			N/A

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 0.79% for Class Z shares and 1.08% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Ametek Aerospace/Industrial Instruments	2.6	%
2.	SEI Investments Mutual Fund Administration & Investment Management	2.3	%
3.	Donaldson Industrial Air Filtration	2.1	%
4.	Mettler-Toledo International Laboratory Equipment	2.1	%
5.	Cepheid Molecular Diagnostics	2.0	%
6.	Nordson Dispensing Systems for Adhesives & Coatings	1.7	%
7.	Amphenol Electronic Connectors	1.7	%
8.	LKQ Alternative Auto Parts Distribution	1.3	%
9.	Synageva BioPharma Biotech Focused on Orphan Diseases	1.3	%
10.	Associated Banc-Corp Midwest Bank	1.2	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA ACORN INTERNATIONAL®

IN A NUTSHELL


P. Zachary Egan Co-Portfolio Manager				Louis J. Mendes III Co-Portfolio Manager

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. International investing involves certain risks and volatility due to potential political, economic or currency instabilities and different, potentially less stringent, financial and accounting standards than those generally applicable to U.S. issuers. Risks are enhanced for emerging market issuers. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. Please also see "A Comment on Trading Volumes" on Page 2 of this report.

Columbia Acorn International Class Z shares returned 4.34% in the first quarter of 2015, 0.58% below its primary benchmark, the S&P Global Ex-U.S. Between $500M and $5B® Index. For comparison, the large-cap, developed market MSCI EAFE Index (Net) rose 4.88% during the quarter.

Japan generated the strongest U.S. dollar returns with the Fund's holdings rising over 15% in both local currency and U.S. dollars, as the currency stabilized after a weak 2014. In the quarter, seven of the top 15 performing investments, based on contributions to returns, were domiciled in Japan. In prior reviews, we have noted the strong positive sentiment in Japanese markets stemming from Prime Minister Abe's reform agenda, which was introduced in December 2012. The first two "arrows" of the "Abenomics" agenda, fiscal stimulus and monetary easing, have been successful in generating domestic market optimism, albeit without marked improvement in underlying economic fundamentals. In the first quarter of this year, Japanese regulators proposed a Corporate Governance Code, which constitutes the long-awaited and critical "third arrow" designed to promote improving shareholder returns. As a result, in anticipation of better balance sheet management, many companies that have held large excess cash balances for years showed strong stock price performance. This positive sentiment spilled over into the general market, with domestic-demand oriented companies exhibiting particular buoyancy.

Among the Fund's top performing Japanese positions were Japan Airport Terminal, an airport terminal operator at Haneda that is benefiting from strong inbound Asian tourism, and Ariake Japan, a maker of commercial soup and sauce extracts that has been able to raise prices. Their stocks rose 53% and 42%, respectively, in the quarter. The Japanese market has been characterized for many years by false starts and disappointments. However, we regard government policy moves made in the last two years as among the most aggressive in decades for the world's third largest economy. Representing over 20% of Fund assets, Japan is an important component of the Fund's portfolio.

Europe remains the other large economy seeking to jumpstart economic growth via aggressive monetary easing. Local markets were strong with Fund holdings rising over 17% in local currency. Unfortunately, currency weakness reduced this to roughly 6% in U.S. dollar terms. The fall in European currencies has helped a number of industrial exporters, such as long-time holding Hexagon, a Swedish designer of measurement and visualization software and equipment. Its stock rose over 15% in U.S. dollar terms. Despite ongoing negative headlines over Greek insolvency, European markets appear sanguine about a possible exit scenario.

Many of the Fund's laggards continue to come from Asia ex-Japan, where Hong Kong-listed casinos and retailers struggled on the back of declining Macau gaming and tourist spending in Hong Kong. Casino operator Melco Crown Entertainment and cosmetics retailer Sa Sa International fell 15% and 29%, respectively, while department store operator Lifestyle International fell over 15%. Weak currencies have made Japan and Europe increasingly affordable to mainland Chinese tourists, who seem to be deterred by perceived hostility in Hong Kong and are opting to spend their vacations elsewhere. As the Chinese economy slows and is subject to new anti-corruption policies, the central bank has eased credit in order to backstop declining demand. Whether China will follow the lead of Europe and Japan by launching its own easy money policy remains to be seen, but the trend appears to signal a turnaround in credit availability for the remainder of the year. Latin America was also a laggard, with holdings in Brazil, Mexico, Chile and Guatemala all down over 10% in U.S. dollar terms on weak local economies and a continued bleak outlook for commodity prices.

As we enter the second quarter, there is a clear bifurcation in monetary policy among the world's major economies: Japan, Europe and China combat slowing growth with monetary easing, while the United States is poised to move in the opposite direction. Thus far, the economic impact is most salient in currency moves. While U.S. dollar strength has reduced returns to Fund shareholders, the Fund has not engaged in currency hedging to buoy U.S. dollar returns. Currencies are volatile, their direction difficult to reliably predict, and we believe an unhedged portfolio provides shareholders with the benefit of currency diversification.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

Hexagon	0.8	%
Melco Crown Entertainment—ADR*	0.5
Japan Airport Terminal	0.5
Ariake Japan	0.4
Lifestyle International	0.3
Sa Sa International	0.2

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

*ADR - American Depository Receipts

COLUMBIA ACORN INTERNATIONAL®

AT A GLANCE

Total Net Assets of the Fund:
$7.9 billion

The Growth of a $10,000 Investment in Columbia Acorn International® Class Z Shares

September 23, 1992 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			5 years			10 years			Life of Fund
Class Z (9/23/92 inception)		4.34	%		-1.33	%		8.64	%		9.07	%		10.96	%
Class A (10/16/00 inception)
without sales charge		4.27			-1.62			8.29			8.71			10.54
with sales charge		-1.72			-7.28			7.02			8.07			10.25
S&P Global Ex-U.S. Between $500M® and $5B*		4.92			0.85			7.21			7.93			8.44

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 0.94% for Class Z shares and 1.29% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Coronation Fund Managers (South Africa) South African Fund Manager	1.4	%
2.	CCL Industries (Canada) Global Label Converter	1.1	%
3.	Spotless (Australia) Facility Management & Catering Company	1.0	%
4.	Distribuidora Internacional de Alimentación (Spain) Discount Retailer in Spain & Latin America	1.0	%
5.	Naspers (South Africa) Media in Africa, China, Russia & other Emerging Markets	1.0	%
6.	Neopost (France) Postage Meter Machines	0.9	%
7.	Zee Entertainment Enterprises (India) Indian Programmer of Pay Television Content	0.9	%
8.	Rand Merchant Insurance (South Africa) Directly Sold Property & Casualty Insurance; Holdings in other Insurers	0.9	%
9.	Domino's Pizza Enterprises (Australia) Domino's Pizza Operator in Australia & New Zealand	0.9	%
10.	President Chain Store (Taiwan) Convenience Chain Store Operator in Taiwan	0.9	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA ACORN USA®

IN A NUTSHELL


Robert A. Mohn Lead Portfolio Manager				William J. Doyle Co-Portfolio Manager

Columbia Acorn USA Class Z shares ended the first quarter of 2015 up 5.12%, outperforming the 4.32% gain of its primary benchmark, the Russell 2000 Index. Outperformance in the quarter was driven by favorable stock selection in the information technology (IT) and consumer discretionary sectors.

IT stock IPG Photonics, a maker of fiber lasers, was the top contributor to gains in the quarter, increasing 23% on solid year-over-year revenue growth. Other winners in the sector included Infinera, a maker of optical networking equipment, whose stock rose 33%. Infinera reported strong fourth quarter growth on robust demand for its long haul optical products. ExlService Holdings, a business process outsourcing company, gained 30% by adding enough new business to grow through the loss of a large insurance client. SPS Commerce, a developer of supply chain management software delivered via the web, gained 19% on solid revenue growth and particularly strong gains in a new analytics offering for retailing suppliers. Informatica, a developer of enterprise data integration software, gained 15% in the quarter, as its stock price began to incorporate a take-out premium based on multiple media reports indicating a sale of the company was near. Just following the quarter end on April 7, Informatica agreed to be acquired for an 11% premium to their closing price on March 31.

Other winners in the period included self-storage facilities owner Extra Space Storage, up 16%. The company has benefited from strong same-store operating income growth of 10%, along with a spate of accretive acquisitions. Akorn, a manufacturer and distributor of specialty generic drugs, gained 30% in the quarter. Its revenue jumped 168% over the prior year, aided by some significant generic drug price hikes.

Drew Industries, a maker of RV and manufactured home components, gained 24% on solid revenue growth. The company has been increasing market share in the fast-growing towable RV end market. Drew Industries' strong quarter helped drive the Fund's relative outperformance in the consumer discretionary sector.

The Fund's investments in car rental companies Avis Budget Group and Hertz detracted from gains during the quarter. Down 12% and 13%, respectively, the stocks fell on concerns over weaker-than-expected pricing. Hardwood flooring retailer Lumber Liquidators fell 48% after the company received negative publicity. We opted to sell the Fund's position in the stock. Down 15%, truck dealership Rush Enterprises (Class A) was impacted by weaker energy prices, as 10% of its truck sales are to energy supply chain customers. NetSuite, a developer of

end-to-end IT systems solutions delivered via the web, fell 15%. The company had good revenue growth of 37% but suffered from lower margins.

We are pleased with the Fund's first quarter performance. We believe the outlook is favorable for the majority of the stocks that the Fund owns given domestic economic growth. We also believe Fund positions with some exposure to growing emerging market populations and incomes should be beneficial going forward.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

Extra Space Storage	3.1	%
IPG Photonics	2.6
Drew Industries	2.5
Avis Budget Group	1.9
Akorn	1.6
ExlService Holdings	1.4
SPS Commerce	1.2
Rush Enterprises*	1.1
NetSuite	0.8
Infinera	0.7
Informatica	0.7
Hertz	0.6

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

*The Fund is invested in Class A and Class B shares of this company.

COLUMBIA ACORN USA®

AT A GLANCE

Total Net Assets of the Fund:
$1.3 billion

The Growth of a $10,000 Investment in Columbia Acorn USA® Class Z Shares

September 4, 1996 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			5 years			10 years			Life of Fund
Class Z (9/4/96 inception)		5.12	%		8.22	%		13.54	%		8.16	%		10.96	%
Class A (10/16/00 inception)
without sales charge		5.08			7.97			13.24			7.86			10.59
with sales charge		-0.97			1.75			11.91			7.23			10.24
Russell 2000 Index*		4.32			8.21			14.57			8.82			8.82

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 1.07% for Class Z shares and 1.33% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Mettler-Toledo International Laboratory Equipment	3.4	%
2.	Ametek Aerospace/Industrial Instruments	3.1	%
3.	Extra Space Storage Self Storage Facilities	3.1	%
4.	Nordson Dispensing Systems for Adhesives & Coatings	3.0	%
5.	HEICO FAA-approved Aircraft Replacement Parts	2.7	%
6.	IPG Photonics Fiber Lasers	2.6	%
7.	Drew Industries RV & Manufactured Home Components	2.5	%
8.	Donaldson Industrial Air Filtration	2.4	%
9.	Cepheid Molecular Diagnostics	2.1	%
10.	Synageva BioPharma Biotech Focused on Orphan Diseases	2.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA ACORN INTERNATIONAL SELECT^SM

IN A NUTSHELL


Christopher J. Olson Portfolio Manager

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. Foreign investments subject the Fund to political, economic, market, social and other risks within a particular country, as well as to potential currency instabilities and less stringent financial and accounting standards generally applicable to U.S. issuers. Risks are enhanced for emerging market issuers. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. The Fund may invest significantly in issuers within a particular sector, which may be negatively affected by market, economic or other conditions, making the Fund more vulnerable to unfavorable developments in the sector. Please also see "A Comment on Trading Volumes" on Page 2 of this report.

Columbia Acorn International Select Class Z shares ended the first quarter of 2015 up 1.48%. This compares to a 5.61% gain for the Fund's primary benchmark, the S&P Developed Ex-U.S. Between $2B and $10B® Index. On a regional basis, a large part of the Fund's relative underperformance was tied to exposure in Asia (excluding Japan), Latin America and other emerging markets. On a sector basis, materials stocks and financials were the biggest relative detractors.

Six of the Fund's top 10 contributors in the quarter were Japanese companies and included Secom, a provider of security services. The company's stock gained 17% as investors sold export stocks on yen strength and moved into stable domestic businesses like Secom. Park24, a parking lot operator in Japan, gained 39%, benefiting from the same trend. Japan Tobacco, a maker of cigarettes, had a 15% gain as investors became more comfortable with the outlook for its Russian operations and management undertook a stock buyback. Recruit Holdings, a provider of recruitment and media services, gained 10% on the back of improved labor conditions, which drove better-than-expected earnings. Abroad, its recent acquisitions, such as indeed.com, an employment-related search engine, continued to grow strongly.

Outside Japan, Naspers, a South African provider of media to emerging markets, gained 18%. Chinese Internet company Tencent is Naspers' primary investment and it continued to report robust revenue and earnings gains. CJ Corp, a holding company of a Korean consumer conglomerate, had a strong quarter, gaining 12% as new management continued to successfully implement restructuring programs.

Laggards in the quarter included Tahoe Resources, a silver miner operating in Guatemala. Its stock fell 21% as investors worried about political risk in Guatemala and responded negatively to the company's proposed merger with Peru-based miner Rio Alto Mining. Babcock International, a UK public sector outsourcer, fell 11% as investors took profits in the stock in anticipation of a volatile election season. Canadian oil and gas producer Baytex fell 16% with the drop in oil prices. We opted to sell the Fund's position during the quarter. Coronation Fund Managers, a South African fund manager, fell 19% in the quarter on profit taking after a strong 2014. Japanese auto parts manufacturer NGK Spark Plug also changed direction in the quarter, declining 11% as export stocks were sold on the back of the stronger yen.

Global liquidity remains supportive to most equity markets. As a result, stock valuations have risen. In addition to paying careful attention to the valuations of our holdings, we strive to be mindful about the impact of monetary policy on the underlying businesses. As easy liquidity is likely to be only a temporary benefit, we will endeavor to be certain that the businesses we invest in can stand on their own once policy support is withdrawn.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

Recruit Holdings	3.8	%
Secom	3.6
Tahoe Resources	2.7
Japan Tobacco	2.5
CJ Corp	2.4
NGK Spark Plug	2.3
Naspers	2.1
Babcock International	2.0
Coronation Fund Managers	1.9
Park24	1.5

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

The Fund's concentrated investments in a limited number of stocks will cause the Fund to diverge significantly from benchmark weightings and may subject the Fund to greater risk and volatility than its benchmark and the other Columbia Acorn Funds.

COLUMBIA ACORN INTERNATIONAL SELECT^SM

AT A GLANCE

Total Net Assets of the Fund:
$241.9 million

The Growth of a $10,000 Investment in Columbia Acorn International Select^SM Class Z Shares

November 23, 1998 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			5 years			10 years			Life of Fund
Class Z (11/23/98 inception)		1.48	%		-8.18	%		7.49	%		7.75	%		8.75	%
Class A (10/16/00 inception)
without sales charge		1.41			-8.44			7.13			7.41			8.40
with sales charge		-4.41			-13.70			5.87			6.78			8.01
S&P Developed Ex-U.S. Between $2B and $10B® Index*		5.61			1.12			7.85			6.72			7.66

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 1.21% for Class Z shares and 1.49% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Singapore Exchange (Singapore) Singapore Equity & Derivatives Market Operator	5.0	%
2.	Challenger Financial (Australia) Annuity Provider in Australia	4.6	%
3.	CapitaMall Trust (Singapore) Singapore Commercial Property Real Estate Investment Trust	4.3	%
4.	Recruit Holdings (Japan) Recruitment & Media Services	3.8	%
5.	KDDI (Japan) Mobile & Fixed Line Communication Service Provider in Japan	3.7	%
6.	Secom (Japan) Security Services	3.6	%
7.	CCL Industries (Canada) Global Label Converter	3.1	%
8.	Telefonica Deutschland (Germany) Mobile & Fixed-line Communications in Germany	3.1	%
9.	Tahoe Resources (Guatemala) Silver Project in Guatemala	2.7	%
10.	Partners Group (Switzerland) Private Markets Asset Management	2.6	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA ACORN SELECT^SM

IN A NUTSHELL


Robert A. Chalupnik Portfolio Manager

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. Foreign investments subject the Fund to risks, including political, economic, market, social and other risks, within a particular country, as well as to potential currency instabilities and less stringent financial and accounting standards generally applicable to U.S. issuers. Risks are enhanced for emerging market issuers. The Fund may invest significantly in issuers within a particular sector, which may be negatively affected by market, economic or other conditions, making the Fund more vulnerable to unfavorable developments in the sector.

Columbia Acorn Select Class Z shares ended the first quarter of 2015 up 2.83%, underperforming the 5.31% gain of its primary benchmark, the S&P MidCap 400® Index. Industrial stocks were the largest detractors from relative performance in the period, accounting for over half of the Fund's underperformance versus the benchmark.

Top contributors in the quarter came from a variety of sectors. WNS, a provider of offshore business process outsourcing services, gained 17%. The company benefited from better-than-expected earnings driven by a new CEO who has been successful in improving company growth. We trimmed the position during the quarter to manage its size and risk. Amphenol, a manufacturer of electronic connectors, gained 10% on strong earnings and despite reducing the company's outlook for 2015. Mutual fund administrator and investment manager SEI Investments also gained 10% for the three-month period. SEI has had strong cash inflows into its actively managed strategies. Intercept Pharmaceuticals, a biotech developing drugs for several diseases, had an impressive 74% gain in the quarter. Its drug OCA, which is being developed to treat severe liver disease, received "breakthrough" designation from the FDA. This designation is given to drugs that show early promise in treating a poorly managed disease and indicates that the FDA will work closely with the company to expedite approval. We opted to sell the Fund's position in Intercept to capture the strong gains in the quarter.

Turning to underperformers, the biggest detractor from performance in the industrial sector was air filtration company Donaldson, which fell 2%. As the third largest position in the Fund, this relatively small drop had a significant impact. Donaldson reported disappointing earnings due to weaker filter sales to its agriculture end market, and the company also faced a currency headwind due to the strong U.S. dollar. Although Donaldson's results were disappointing, we continue to like the stock and its long-term prospects. Donaldson should benefit from demand for replacement filters and its worldwide presence gives the company the ability to move manufacturing to better compensate for currency headwinds.

Outside the industrial sector, other large detractors in the quarter included F5 Networks, a provider of Internet traffic management equipment that fell 12%. F5's earnings missed expectations due to reduced demand from its end markets, which include the U.S. Government as well as large corporate enterprises. PVH, an apparel wholesaler and retailer, fell 20% on weaker-than-expected results and reduced guidance for 2016. While sales in the company's core brands grew, they were below management's targets and, with a large portion of its sales outside of the United States, the currency headwind was also a problem. We opted to sell out of the position during the quarter. LKQ, a distributor of alternative auto parts for the collision

industry, fell 9% in the quarter on an earnings miss and lower-than-expected guidance for 2015. The strong dollar and falling commodity prices, mainly in scrap steel, hurt the company. We believe the long-term prospects for LKQ are strong, however, and took advantage of the downturn to add to the position.

The Fund's first quarter and 2014 year-end relative performance were disappointing. Although our principal investment strategy has not changed, we continue to look for ways to improve the performance of the Fund's portfolio. One notable change during the quarter was the reduction in exposure to small energy exploration and production companies that have operations outside the United States. With oil prices down, we believe the prospects for these smaller companies operating in emerging markets have been greatly reduced. We sold out of four energy positions and added three new energy ideas to the portfolio, resulting in an increased exposure to the U.S. shale energy market. Although low oil prices have curtailed drilling in this area, the energy companies held by the Fund have proven reserves and have been profitable at lower oil and gas prices. Another notable change to the portfolio was the increase in turnover of individual securities. We added eight new positions to the Fund and sold out of 11 during the quarter. This amount of portfolio turnover is higher than the Fund has experienced in the recent past and reflects our ongoing effort to focus the Fund on our team's favorite ideas. We believe these changes should benefit patient investors.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

Amphenol	4.7	%
Donaldson	4.6
SEI Investments	4.3
LKQ	4.3
WNS—ADR*	3.5
F5 Networks	3.3

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

*ADR - American Depository Receipts

COLUMBIA ACORN SELECT^SM

AT A GLANCE

Total Net Assets of the Fund:
$623.4 million

The Growth of a $10,000 Investment in Columbia Acorn Select^SM Class Z Shares

November 23, 1998 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			5 years			10 years			Life of Fund
Class Z (11/23/98 inception)		2.83	%		5.72	%		9.38	%		8.22	%		10.31	%
Class A (10/16/00 inception)
without sales charge		2.76			5.40			9.06			7.91			9.96
with sales charge		-3.14			-0.64			7.78			7.27			9.56
S&P MidCap 400® Index*		5.31			12.19			15.72			10.32			10.79

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 1.03% for Class Z shares and 1.31% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Ametek Aerospace/Industrial Instruments	6.4	%
2.	Amphenol Electronic Connectors	4.7	%
3.	Donaldson Industrial Air Filtration	4.6	%
4.	SEI Investments Mutual Fund Administration & Investment Management	4.3	%
5.	LKQ Alternative Auto Parts Distribution	4.3	%
6.	WNS—ADR Offshore Business Process Outsourcing Services	3.5	%
7.	F5 Networks Internet Traffic Management Equipment	3.3	%
8.	Nordson Dispensing Systems for Adhesives & Coatings	3.3	%
9.	Solera Holdings Software for Automotive Insurance Claims Processing	3.2	%
10.	Mettler-Toledo International Laboratory Equipment	3.1	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA THERMOSTAT FUND^SM

IN A NUTSHELL


Charles P. McQuaid Lead Portfolio Manager				Christopher J. Olson Co-Portfolio Manager

A "fund of fund" bears its allocable share of the costs and expenses of the underlying funds in which it invests. Such funds are thus subject to two levels of fees and potentially higher expense ratios than would be associated with a fund that invests and trades directly in financial instruments under the direction of a single manager.

The value of an investment in the Fund is based primarily on the performance of the underlying funds in which it invests. The Fund is subject to the risk that the Investment Manager's decisions regarding asset classes and underlying funds will not anticipate market trends successfully, resulting in a failure to preserve capital or lower total return. The Investment Manager may prefer an underlying fund in the Columbia Acorn Family of Funds over alternative investments. There can be no assurance that the Columbia Acorn Funds will outperform similar funds managed by the Investment Manager's affiliates. This is not an offer of the shares of any other mutual fund mentioned herein.

Columbia Thermostat Fund Class Z shares ended the first quarter of 2015 up 1.50%. This compares to a 0.95% quarterly gain of the Fund's primary equity benchmark, the S&P 500® Index. The Fund's primary debt benchmark, the Barclays U.S. Aggregate Bond Index, rose 1.61% in the quarter, and the 50/50 Blended Benchmark gained 1.37% for the same period. Relative performance for the Fund improved in the first quarter, topping the equity index and the blended benchmark (defined on Page 5).

The weighted average gain for the Fund's equity portfolio was 2.60% for the first quarter, led by the performance of Columbia Select Large Cap Growth Fund, up 5.73%. The bond portion of the Fund had a weighted average gain of 1.49% for the first quarter. Columbia Income Opportunities Fund led bond performance, increasing 2.92%.

The Fund hit one reallocation trigger in the first quarter, reducing stock exposure to 10% after the S&P 500® surpassed the 2,020 level.

During the first quarter of 2015, we conducted the periodic review of underlying funds called for by Columbia Thermostat Fund's prospectus. As a result, we expect to make the following changes during the second quarter:*

• Columbia Acorn Fund's weighting will decrease from 15% to 10% of the equity portfolio.

• Columbia Contrarian Core Fund's weighting will increase from 15% to 20% of the equity portfolio.

• Columbia Intermediate Bond Fund will decrease from 25% to 20% of the bond portfolio.

• Columbia U.S. Government Mortgage Fund will increase from 15% to 20% of the bond portfolio.

• The stock/bond allocation table levels will be revised. The Fund will move to 10% stocks at an S&P 500® level over 2,225, up from 2,020. The Fund will move to 90% stocks at a level of 1,100 or less, up from 970. In between, a 75 point move in the S&P 500® will trigger a 5% point change in allocation of stock and bond funds.

This year's changes in stock weightings resulted in Columbia Thermostat Fund having closer to a market weight in larger cap stocks. We believe the changes in bond weightings will modestly boost the yield of Thermostat's bond portfolio. In 2014, we made changes to the Fund's

allocation table, recognizing that we can no longer assume that price-to-earnings (PE) ratios will compress but, instead, the S&P 500® will trade within its broad historical PE ratio range on normalized (long-term moving average) earnings. This year, we refined our methodology to account for normalized earnings likely rising during the year, as low earnings spool off the moving average.

*These changes were implemented with the Fund's May 1, 2015 prospectus.

Results of the Funds Owned in Columbia Thermostat Fund

as of March 31, 2015

Stock Funds

Fund	Weightings in category			1st quarter performance
Columbia Acorn International, Class I		20	%		4.38	%
Columbia Dividend Income Fund, Class I		20	%		-0.33	%
Columbia Acorn Fund, Class I		15	%		4.00	%
Columbia Contrarian Core Fund, Class I		15	%		1.25	%
Columbia Acorn Select, Class I		10	%		2.90	%
Columbia Large Cap Enhanced Core Fund, Class I		10	%		1.31	%
Columbia Select Large Cap Growth Fund, Class I		10	%		5.73	%
Weighted Average Equity Gain		100	%		2.60	%

Bond Funds

Fund	Weightings in category			1st quarter performance
Columbia Short Term Bond Fund, Class I		40	%		0.58	%
Columbia Intermediate Bond Fund, Class I		25	%		1.93	%
Columbia Income Opportunities Fund, Class I		20	%		2.92	%
Columbia U.S. Government Mortgage Fund, Class I		15	%		1.27	%
Weighted Average Income Gain		100	%		1.49	%

Columbia Thermostat Fund Rebalancing in the First Quarter

January 21, 2015

10% stocks, 90% bonds

The Fund's investments in the underlying funds may present certain risks, including the following. Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. The Fund's investment in other funds subjects it to the investment performance (positive or negative), risks and expenses of these underlying funds. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than in investments in larger, more established companies. There are risks associated with fixed income investments, including credit risk, market risk, interest rate risk and prepayment and extension risk. In general, bond prices fall when interest rates rise and vice versa. This effect is more pronounced for longer-term securities. Non-investment-grade (high-yield or junk) securities present greater price volatility and more risk to principal and income than higher rated securities. Foreign investments subject the Fund to political, economic, market, social and other risks within a particular country, as well as to potential currency instabilities and less stringent financial and accounting standards generally applicable to U.S. issuers. Risks are enhanced for emerging market issuers.

COLUMBIA THERMOSTAT FUND^SM

AT A GLANCE

Total Net Assets of the Fund:
$1.2 billion

The Growth of a $10,000 Investment in Columbia Thermostat Fund^SM Class Z Shares

September 25, 2002 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			5 years			10 years			Life of Fund
Class Z (9/25/02 inception)		1.50	%		5.11	%		9.33	%		6.83	%		7.95	%
Class A (3/3/03 inception)
without sales charge		1.41			4.85			9.05			6.56			7.68
with sales charge		-4.44			-1.20			7.76			5.93			7.17
S&P 500® Index*		0.95			12.73			14.47			8.01			9.90
Barclays U.S. Aggregate Bond Index*		1.61			5.72			4.41			4.93			4.71

Results for other share classes can be found on Page 6.

*The Fund's primary benchmarks. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 0.80% for Class Z shares and 1.05% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit columbiathreadneedleus.com/investment-products/mutual-funds/appended-performance for more information.

Asset Allocation

as a percentage of net assets, as of 3/31/15

Portfolio Weightings

as a percentage of assets in each investment category, as of 3/31/15

Stock Mutual Funds

Columbia Acorn International, Class I	20	%
Columbia Dividend Income Fund, Class I	20	%
Columbia Acorn Fund, Class I	15	%
Columbia Contrarian Core Fund, Class I	15	%
Columbia Acorn Select, Class I	10	%
Columbia Large Cap Enhanced Core Fund, Class I	10	%
Columbia Select Large Cap Growth Fund, Class I	10	%

Bond Mutual Funds

Columbia Short Term Bond Fund, Class I	40	%
Columbia Intermediate Bond Fund, Class I	25	%
Columbia Income Opportunities Fund, Class I	20	%
Columbia U.S. Government Fund, Class I	15	%

COLUMBIA ACORN EMERGING MARKETS FUND^SM

IN A NUTSHELL


Fritz Kaegi Lead Portfolio Manager				Stephen Kusmierczak Lead Portfolio Manager

P. Zachary Egan Co-Portfolio Manager				Louis J. Mendes III Co-Portfolio Manager

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. International investing involves certain risks and volatility due to potential political, economic or currency instabilities and different, potentially less stringent, financial and accounting standards than those generally applicable to U.S. issuers. Risks are enhanced for emerging and frontier market issuers. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. Please also see "A Comment on Trading Volumes" on Page 2 of this report.

During the first quarter of 2015, Columbia Acorn Emerging Markets Fund Class Z shares fell 0.78%, while its benchmark, the S&P Emerging Markets Between $500M and $5B® Index, rose 1.86%. Since inception through March 31, 2015, the Fund has returned 7.47%, while the benchmark has had an annualized return of 3.61%.

During the quarter, the Fund's main positional bets underperformed. The Fund's largest regional overweight versus the benchmark is Southeast Asia, where we have a 22.5% weight, or 7.4 percentage points over the benchmark. The Fund's main underweight is Greater China, where the Fund has a 26.7% weight but is 14.6 percentage points below the benchmark. The largest sector overweight continues to be in the consumer discretionary sector, where the Fund's 28.2% weight is 13.6 percentage points above benchmark. In financials, the Fund's 12.1% weight is 11.3 percentage points under benchmark. In each of these four main bets, we had subpar stock selection, which explains most of the Fund's underperformance.

The one positional bright spot was that Fund holdings of companies listed outside emerging markets (but with substantial emerging markets economic exposure) performed strongly across the board. These included Italian tire supplier Pirelli (up 23%), UK-listed but Latin America-exposed telecom service provider Cable and Wireless (up 17%), Swedish metrology specialist Hexagon (up 15%), and paint producers Kansai Paint in Japan (up 18%) and Tikkurila in Finland (up 14%).

The largest single regional detractor was Greater China, representing most of the Fund's underperformance. Within the region, the largest detractors were Chinese auto information website BitAuto, down 27%, and Macau-driven casino operator Melco International, down 23%. The market reacted negatively to BitAuto's initiative with JD.com to push further into online auto markets, as the deal's heavy investment in development spending may depress short-term earnings growth. Melco International continues to be hit by unfavorable revenue growth trends in Macau, and general fears that the Chinese anti-corruption drive will continue to depress casino revenues. In Southeast Asia, casino operators Melco Crown (Philippines) Resorts (down 32% for the quarter) and Nagacorp (down 19%) represented nearly all of the underperformance in that region. Both holdings were hit by falling valuations for Asian casino operators and by a general fear that the fundamental causes of negative gaming revenue trends in Macau will extend into the rest of Asia. These two holdings offset the fine performances of two of our Indonesian holdings, consumer-branded food manufacturer Mayora Indah (up 31%) and retailer

Matahari Department Store (up 26%). Both are in strong fundamental health, including reporting better margins, in spite of a difficult economic environment.

Within consumer discretionary, the three casino operators mentioned above were the largest detractors. Indian pay TV programmer Zee Entertainment Enterprises, down 9%, also hurt performance because it is a large holding. Investors are still skeptical that digitalization of the Indian cable TV market will translate into sustainably higher revenues for owners of content, especially in the short term. This weakness offset the 32% gain posted by auto part maker Bosch (India), which has been carried upward by the Indian auto industry's return to growth. Within financials, the 18% decline in the Fund's largest holding, Coronation Fund Managers, was the most important detractor. With inflows continuing and South African financial markets posting good returns, its stock fell on profit taking after a strong 2014.

How are we responding to this underperformance? First, we have further scrutinized Fund casino holdings and cut weightings, especially since these stocks seem to be more highly correlated than their geographic dispersion would suggest. We still believe they are excellent business franchises, but we are more cautious about the impact of Chinese state policy on the industry. Second, we are making a push to refresh the portfolio with new holdings. We added eight new holdings during the quarter and added several more after quarter's end. All of these were fruits of an intensive period of travel and investigation by our analysts.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

Coronation Fund Managers	3.5	%
Zee Entertainment Enterprises	2.9
Melco International	2.2
Cable and Wireless	2.0
Melco Crown (Philippines) Resorts	1.9
Nagacorp	1.7
Hexagon	1.6
Bosch	1.6
Matahari Department Store	1.4
BitAuto—ADR*	1.4
Kansai Paint	1.3
Tikkurila	1.2
Mayora Indah	1.1
Pirelli	1.0

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

Columbia Acorn Emerging Markets Fund is closed to most new investors and new accounts with certain exceptions. Refer to the Fund's prospectus for details.

*ADR - American Depository Receipts

COLUMBIA ACORN EMERGING MARKETS FUND^SM

AT A GLANCE

Total Net Assets of the Fund:
$449.3 million

The Growth of a $10,000 Investment in Columbia Acorn Emerging Markets Fund^SM Class Z Shares

August 19, 2011 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			Life of Fund
Class Z (8/19/11 inception)		-0.78	%		-3.94	%		7.47	%
Class A (8/19/11 inception)
without sales charge		-0.86			-4.17			7.17
with sales charge		-6.59			-9.70			5.43
S&P Emerging Markets Between $500M and $5B® Index*		1.86			3.07			3.61

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 1.59% for Class Z shares and 1.81% for Class A shares.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Coronation Fund Managers (South Africa) South African Fund Manager	3.5	%
2.	AMVIG Holdings (China) Chinese Tobacco Packaging Material Supplier	3.1	%
3.	Zee Entertainment Enterprises (India) Indian Programmer of Pay Television Content	2.9	%
4.	Koh Young Technology (South Korea) Inspection Systems for Printed Circuit Boards	2.3	%
5.	Rand Merchant Insurance (South Africa) Directly Sold Property & Casualty Insurance; Holdings in other Insurers	2.2	%
6.	Melco International (Hong Kong) Macau Casino Operator	2.2	%
7.	Halyk Savings Bank of Kazakhstan—GDR (Kazakhstan) Retail Bank & Insurer in Kazakhstan	2.1	%
8.	President Chain Store (Taiwan) Convenience Chain Store Operator in Taiwan	2.1	%
9.	Cable and Wireless (United Kingdom) Telecommunications Service Provider in the Caribbean	2.0	%
10.	Adani Ports & Special Economic Zone (India) Indian West Coast Shipping Port	1.9	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA ACORN EUROPEAN FUND^SM

IN A NUTSHELL


Andreas Waldburg-Wolfegg Lead Portfolio Manager				Stephen Kusmierczak Co-Portfolio Manager

Columbia Acorn European Fund Class Z shares gained 4.39% in the first quarter of 2015, underperforming the 5.32% gain of its primary benchmark, the S&P Europe Between $500M and $5B® Index. For the trailing 12 months, the Fund lost 4.98%, less than the benchmark's decline of 6.11%. Over three years, the Fund has returned 11.36% on an annualized basis versus the benchmark's annualized gain of 14.19%. While we are disappointed in the Fund's underperformance versus the benchmark, it should be pointed out that the Fund appears to be less risky than its benchmark, and outperforms it on a risk-adjusted basis.*

In the first quarter, the largest performance detractors versus the benchmark by region were holdings in the Mediterranean. Italy was among the best performing markets in the Fund's benchmark in the quarter. Italian tire supplier Pirelli gained 23%, outpacing the benchmark return of 18% in Italy, but our approximately 60% underweight cost the Fund 51 basis points** of equity performance. Positively in Spain, three out of four Fund holdings gained over 14% in U.S. dollar terms versus the country return of 8% in the benchmark, contributing 33 basis points to performance. Yet this gain was offset by weakness in our French holdings. Following a year marked by significant asset sales, French online advertising company Hi-Media reported disappointing operating earnings and the stock declined 21%. This explains over half of the Fund's 34 basis point equity loss in France.

The Nordic region was the largest contributor to Fund performance versus the benchmark in the quarter. Fund holdings in Norway, Finland and Denmark all beat their country benchmarks by 11%, 3% and 2%, respectively. The largest performance contributor for Norway was consumer company Orkla, up 11%. The company continues to divest non-core assets, and reported a return to growth across all its food and consumer care businesses. IT hardware and services company Atea (up 9%) is a long-term holding and has benefited from a recovery in hardware sales in this highly cash-generative business. Together, both holdings added 36 basis points to Fund performance.

Looking ahead, what do we perceive as the key risks and opportunities for the Fund? European equities have rallied sharply in the first quarter. While evidence is building that muted recoveries are underway in core Europe, as well as the lagging Mediterranean countries, most of the recent gains reflect mark ups in valuation multiples. The market appears to be anticipating a stronger recovery in Europe following the European Central Bank's implementation of quantitative easing. In the United States, a much larger bond-buying program started in 2009 that has fueled a multi-year boom in equities. Also, in light of bond yields,

which have declined to near zero or even turned negative, as in Switzerland and Denmark, equity multiples and dividend yields look attractive in a relative context.

Current momentum and liquidity-driven markets are challenging for bottom-up stock pickers like us who focus on company fundamentals and attempt to have a more informed view of the intrinsic value of the businesses we own. There is a risk that as market sentiment improves in countries like Italy, where we are underweight because we haven't found companies we want to invest in at a reasonable price, we will continue to underperform. We intend to maintain our focus on owning quality franchises with higher returns on capital and solid balance sheets. We believe that if European equity markets do reverse, investors will benefit from the Fund's defensive characteristics.

Fund's Positions in Mentioned Holdings

As a percentage of net assets, as of 3/31/15

Orkla	1.3	%
Pirelli	1.0
Hi-Media	1.0
Atea	1.0

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security. Top holdings exclude short-term holdings and cash, if applicable.

* Based on a three-year 0.78% beta and 2.93% alpha.

** A basis point is 1/100 of a percent.

COLUMBIA ACORN EUROPEAN FUND^SM

AT A GLANCE

Total Net Assets of the Fund:
$42.4 million

The Growth of a $10,000 Investment in Columbia Acorn European Fund^SM Class Z Shares

August 19, 2011 (Fund inception) through March 31, 2015

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period.

Average Annual Total Returns for period ended March 31, 2015

	1st quarter			1 year			Life of Fund
Class Z (8/19/11 inception)		4.39	%		-4.98	%		12.83	%
Class A (8/19/11 inception)
without sales charge		4.32			-5.23			12.53
with sales charge		-1.64			-10.67			10.71
S&P Europe Between $500M and $5B® Index*		5.32			-6.11			14.42

Results for other share classes can be found on Page 6.

*The Fund's primary benchmark. Please see Page 5 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2014, prospectus, the Fund's annual operating expense ratio is 1.51% for Class Z shares and 1.76% for Class A shares.

Portfolio Diversification

as a percentage of net assets, as of 3/31/15

Top 10 Holdings

as a percentage of net assets, as of 3/31/15

1.	Assura (United Kingdom) UK Primary Health Care Property Developer	3.6	%
2.	Distribuidora Internacional de Alimentación (Spain) Discount Retailer in Spain & Latin America	3.1	%
3.	Spirax Sarco (United Kingdom) Steam Systems for Manufacturing & Process Industries	2.4	%
4.	Geberit (Switzerland) Plumbing Supplies	2.4	%
5.	Aurelius (Germany) European Turnaround Investor	2.3	%
6.	Partners Group (Switzerland) Private Markets Asset Management	2.3	%
7.	Neopost (France) Postage Meter Machines	2.2	%
8.	Cable and Wireless (United Kingdom) Telecommunications Service Provider in the Caribbean	2.0	%
9.	Babcock International (United Kingdom) Public Sector Outsourcer	2.0	%
10.	Aalberts Industries (Netherlands) Flow Control & Heat Treatment	2.0	%

The Fund's top 10 holdings and portfolio diversification vary with changes in portfolio investments. See the Statement of Investments for a complete list of the Fund's holdings.

COLUMBIA ACORN® FUND

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Information
Bankrate		6,300,300		7,250,000
Cadence Design Systems		2,000,000		4,155,000
CalAmp		1,118,000		1,619,000
Discovery Communications Series C		670,000		1,154,000
F5 Networks		582,000		629,000
FLIR Systems		1,383,000		1,895,000
Genpact		1,405,000		1,531,000
Global Eagle Entertainment		1,000,000		2,001,000
Globalstar		31,000,000		34,500,000
Gogo		2,000,000		3,458,800
GTT Communications		1,950,000		2,601,000
IGATE		3,600,000		3,650,000
RetailMeNot		1,112,930		1,830,000
Solera Holdings		989,000		1,668,000
Stratasys		371,000		504,000
Textura		800,283		1,134,283
Ultimate Software		450,000		554,000
VeriFone Holdings		849,000		1,250,000
Verint Systems		365,000		1,306,000
Verisign		350,000		1,210,000
Vonage		14,044,775		14,500,000
Zayo Group Holdings		925,000		1,150,000
Industrial Goods & Services
Allegion		188,400		626,000
Dorman Products		867,721		957,721
LKQ		5,423,000		7,481,000
Quanta Services		3,309,894		3,400,000
Finance
Associated Banc-Corp		9,000,000		9,414,000
BOK Financial		1,800,000		2,027,000
Eaton Vance		3,283,508		3,463,508
Leucadia National		3,552,000		3,875,000
MSCI		0		195,201
TrustCo Bank		2,136,500		3,136,500
WEX		720,000		863,000
Health Care
Agios Pharmaceuticals		0		275,000
Align Technology		448,000		513,000
Ultragenyx Pharmaceutical		1,164,974		1,704,000
Wright Medical Group		1,255,500		1,729,500

	Number of Shares
	12/31/14		3/31/15
Consumer Goods & Services
Blackhawk Network		700,000		994,000
Fossil		362,145		880,145
Gentex		1,826,000		2,732,952
Papa John's International		478,000		950,000
Select Comfort		1,900,000		2,224,284
Other Industries
Amerco		170,000		190,000
Heartland Express		496,024		1,800,000
Wisconsin Energy		500,000		577,000
Energy & Minerals
Carrizo Oil & Gas		926,000		1,037,000
Cimarex Energy		0		420,000
Energen Corporation		717,000		732,000
Kirkland Lake Gold (Canada)		6,347,100		6,697,200
ShaMaran Petroleum (Iraq)		28,962,000		107,561,000

	Number of Shares
	12/31/14		3/31/15
Sales
Information
Amber Road		2,000,000		0
Amphenol		5,416,000		4,010,000
Ansys		2,500,000		1,806,000
Atmel		4,717,000		4,467,000
Audience		2,150,000		1,644,000
Avnet		1,887,000		1,621,000
Belden		475,000		450,000
Cogent Communications		2,200,000		1,572,000
Covisint		540,000		0
DemandWare		1,152,000		561,300
E2Open		2,575,000		0
Exa		554,391		0
ExlService Holdings		1,407,000		1,333,000
Five9		1,728,000		0
Global Payments		1,700,000		1,261,000
Hackett Group		2,903,719		2,700,000
Hexagon (Sweden)		1,622,000		0
Infinera		2,711,000		2,568,000
Informatica		5,200,000		2,080,000
IPG Photonics		1,504,000		1,399,000
Ixia		1,006,000		0
Kinaxis (Canada)		708,300		0
Lamar Advertising		1,000,000		725,000
Liberty Global Series C		800,000		366,000
Mettler-Toledo International		1,162,000		911,000
Navigant Consulting		4,128,523		3,100,000
NetSuite		640,000		570,149
Pandora Media		2,843,000		0
Plexus		451,458		0
Rightmove (United Kingdom)		155,205		0
Rogers		569,000		539,000
SBA Communications		1,600,000		1,300,000
SPS Commerce		1,330,000		1,076,000
Syntel		497,000		0
Tangoe		641,952		0
Trimble Navigation		3,651,000		3,458,000
Tyler Technologies		470,000		220,000
Verisk Analytics		1,900,000		1,429,000
Virtusa		1,658,000		1,570,000
Workiva		826,390		0
Zebra Technologies		501,000		474,000
Industrial Goods & Services
Aalberts Industries (Netherlands)		2,189,385		0
Acuity Brands		960,000		726,000
Airgas		880,000		853,000
Ametek		7,130,000		6,910,000
Boise Cascade		600,000		0
Chicago Bridge & Iron		1,299,000		0

	Number of Shares
	12/31/14		3/31/15
ESCO Technologies		1,948,000		1,489,000
Fortune Brands Home & Security		1,050,000		660,000
Generac		3,632,000		2,982,000
HEICO		3,626,750		3,514,750
Insperity		715,000		0
KAR Auction Services		1,316,000		0
Kennametal		2,674,000		2,592,000
Lindsay		93,147		0
Lumber Liquidators		500,000		0
Middleby		1,050,200		968,200
Mobile Mini		900,000		0
Moog		2,456,000		2,027,000
MRC Global		1,545,000		0
Neopost (France)		664,400		0
Nordson		3,130,000		3,034,000
Novozymes (Denmark)		907,458		0
Pall		1,100,000		846,000
PGT		3,592,200		2,865,200
Rexnord		705,000		0
WABCO Holdings		1,176,000		946,000
Wabtec		1,053,000		1,021,000
Waste Connections		1,100,000		0
Finance
Alliance Data Systems		360,000		0
Allied World Assurance Company Holdings		2,275,000		2,000,000
CAI International		1,500,000		839,000
Cascade Bancorp		2,004,600		0
City National		940,000		0
CNO Financial Group		7,600,000		7,300,000
Coronation Fund Managers (South Africa)		1,356,758		0
Enstar Group		185,000		0
Hancock Holding		1,900,000		1,730,000
HCC Insurance Holdings		1,100,000		910,000
Liberty Tax		472,000		0
Marlin Business Services		902,210		0
MB Financial		2,580,000		2,420,000
McGrath Rentcorp		1,580,000		1,345,000
Rand Merchant Insurance		8,658,000		0
Selective Insurance Group		714,574		0
Valley National Bancorp		1,573,000		0
Wisdom Tree		500,000		0
World Acceptance		808,343		787,422
Heath Care
Abaxis		752,000		595,000
Akorn		4,845,000		3,048,000
Alnylam Pharmaceuticals		362,300		302,300
BioMarin Pharmaceutical		320,200		0

COLUMBIA ACORN® FUND

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED), CONTINUED

	Number of Shares
	12/31/14		3/31/15
Sales (continued)
Heath Care—continued
Castlight Health		863,500		487,818
Celldex Therapeutics		2,401,400		2,140,400
Cepheid		5,350,800		4,909,800
HealthSouth		1,666,323		1,647,700
Intercept Pharmaceuticals		319,200		269,200
NPS Pharmaceuticals		934,400		0
Seattle Genetics		3,398,400		2,548,000
Synageva BioPharma		2,419,209		1,950,318
Consumer Goods & Services
Avis Budget Group		3,700,000		2,450,000
B&G Foods		591,000		0
Boulder Brands		3,484,000		0
Buffalo Wild Wings		157,000		0
Caesarstone (Israel)		630,000		540,000
Casey's General Stores		1,027,709		791,839
Choice Hotels		754,483		729,483
DeVry		800,000		0
Distribuidora Internacional de Alimentación (Spain)		837,052		0
Domino's Pizza		489,000		403,000
Fiesta Restaurant Group		878,000		858,000
Fox Factory Holding		537,804		0
Freshpet		243,000		0
GNC Holdings		478,000		0
Groupon		2,010,000		0
Hertz		3,300,000		2,531,000
Interface		2,758,000		0
Kate Spade & Company		1,796,000		0
Knoll		3,366,000		2,836,000
La-Z-Boy		700,000		0
Michaels Stores		1,162,000		642,492
Performance Sports Group		641,000		0
Pool		1,565,000		1,444,000
Prestige Brands Holdings		611,000		0
Shutterfly		970,000		771,056
ULTA		613,000		0
United Natural Foods		1,303,000		1,286,000
Vail Resorts		1,268,600		895,600
Wayfair		433,000		0
Williams-Sonoma		874,200		595,200
Zulily		1,350,000		425,245
Other Industries
DCT Industrial Trust		1,293,750		0
Deltic Timber		39,381		0
Extra Space Storage		2,000,000		1,467,000
Federal Realty		750,000		717,000
JB Hunt Transport Services		940,000		669,000
Kirby		730,000		720,000
St. Joe		872,926		0

	Number of Shares
	12/31/14		3/31/15
Energy & Minerals
Alexco Resource		2,800,000		0
Allied Nevada Gold		7,103,513		0
Black Diamond Group		214,100		0
Bonanza Creek Energy		203,000		0
Chart Industries		964,000		0
Core Labs (Netherlands)		505,000		423,000
DeeThree Exploration (Canada)		1,400,000		0
FMC Technologies		370,000		0
Horizon North Logistics (Canada)		2,601,900		0
Hornbeck Offshore		1,613,000		1,470,000
Pacific Rubiales Energy (Colombia)		1,800,000		0
Petroamerica Oil (Colombia)		42,000,000		0
Range Resources		632,000		0
RGS Energy		5,000,000		0
Rosetta Resources		1,849,600		1,550,000
Rowan		289,000		0
US Silica		599,000		0
WPX Energy		1,210,000		0

COLUMBIA ACORN® FUND

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 97.0%
Information 28.9%
		> Business Software 6.4%
	1,806,000	Ansys (a)	$	159,271,140
		Simulation Software for Engineers & Designers
	554,000	Ultimate Software (a)		94,155,070
		Human Capital Management Systems
	2,080,000	Informatica (a)		91,218,400
		Enterprise Data Integration Software
	1,668,000	Solera Holdings		86,168,880
		Software for Automotive Insurance Claims Processing
	1,306,000	Verint Systems (a)		80,880,580
		Contact Center & Security Software
	4,155,000	Cadence Design Systems (a)		76,618,200
		Electronic Design Automation Software
	1,076,000	SPS Commerce (a)(b)		72,199,600
		Supply Chain Management Software Delivered via the Web
	570,149	NetSuite (a)		52,887,021
		End-to-end IT Systems Solution Delivered via the Web
	3,741,000	inContact (a)(b)		40,776,900
		Call Center Systems Delivered via the Web & Telco Services
	610,000	Envestnet (a)		34,208,800
		Technology Platform for Investment Advisors
	561,300	DemandWare (a)		34,183,170
		E-Commerce Website Platform for Retailers & Apparel Manufacturers
	699,000	Fleetmatics (a)		31,350,150
		Fleet Management Software
	1,134,283	Textura (a)		30,829,812
		Construction Vendor Management Software
	220,000	Tyler Technologies (a)		26,516,600
		Financial, Tax, Court & Document Management Systems for Local Governments
				911,264,323
		> Instrumentation 4.1%
	911,000	Mettler-Toledo International (a)		299,400,150
		Laboratory Equipment
	1,399,000	IPG Photonics (a)		129,687,300
		Fiber Lasers
	3,458,000	Trimble Navigation (a)		87,141,600
		GPS-based Instruments
	1,895,000	FLIR Systems		59,275,600
		Infrared Cameras
				575,504,650
		> Computer Hardware & Related Equipment 3.1%
	4,010,000	Amphenol		236,309,300
		Electronic Connectors
	539,000	Rogers (a)		44,311,190
		Printed Circuit Materials & High Performance Foams

Number of Shares			Value
	1,250,000	VeriFone Holdings (a)	$	43,612,500
		Point of Sale Systems
	474,000	Zebra Technologies (a)		42,998,910
		Bar Code Printers
	450,000	Belden		42,102,000
		Specialty Cable
	504,000	Stratasys (a)(c)		26,601,120
		Rapid Prototyping & Direct Digital Manufacturing Systems
				435,935,020
		> Mobile Communications 3.1%
	1,300,000	SBA Communications (a)		152,230,000
		Communications Towers
	34,500,000	Globalstar (a)		114,885,000
		Satellite Mobile Voice & Data Carrier
	800,000	Crown Castle International		66,032,000
		Communications Towers
	3,458,800	Gogo (a)(c)		65,924,728
		Provider of Wi-Fi on Airplanes
	2,001,000	Global Eagle Entertainment (a)(c)		26,633,310
		Provider of Entertainment & Wi-Fi on Airplanes
	1,644,000	Audience (a)(b)(c)		7,463,760
		Improving Voice Quality for Mobile Devices
				433,168,798
		> Computer Services 2.7%
	3,650,000	IGATE (a)		155,709,000
		IT & Business Process Outsourcing Services
	1,570,000	Virtusa (a)(b)		64,966,600
		Offshore IT Outsourcing
	1,333,000	ExlService Holdings (a)		49,587,600
		Business Process Outsourcing
	2,025,000	WNS - ADR (a)		49,248,000
		Offshore Business Process Outsourcing Services
	1,531,000	Genpact (a)		35,595,750
		Business Process Outsourcing
	2,700,000	Hackett Group (b)		24,138,000
		IT Integration & Best Practice Research
				379,244,950
		> Business Information & Marketing Services 1.8%
	1,429,000	Verisk Analytics (a)		102,030,600
		Risk & Decision Analytics
	7,250,000	Bankrate (a)(b)		82,215,000
		Internet Advertising for the Insurance, Credit Card & Banking Markets
	3,100,000	Navigant Consulting (a)(b)		40,176,000
		Financial Consulting Firm
	2,570,000	RPX (a)		36,982,300
		Patent Aggregation & Defensive Patent Consulting
				261,403,900

COLUMBIA ACORN® FUND

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Internet Related 1.3%
	1,210,000	Verisign (a)	$	81,033,700
		Internet Domain Registry for .com/.net (Approximately 50% of World Domains)
	14,500,000	Vonage (a)(b)		71,195,000
		Business & Consumer Internet Telephony
	1,830,000	RetailMeNot (a)(c)		32,958,300
		Digital Coupon Marketplace
				185,187,000
		> Telephone & Data Services 1.2%
	1,572,000	Cogent Communications		55,538,760
		Internet Data Pipelines
	2,601,000	GTT Communications (a)(b)		49,106,880
		Provider of High Capacity Data Transit
	1,150,000	Zayo Group Holdings (a)(c)		32,154,000
		Fiber Optic Data Communications
	2,900,000	Boingo Wireless (a)(b)		21,866,000
		Wi-Fi & Cellular Communications Networks
	4,000,000	Towerstream (a)(b)(c)		8,640,000
		High Speed Wireless, Rooftop Antenna Space & Wi-Fi Offload
				167,305,640
		> Telecommunications Equipment 1.1%
	629,000	F5 Networks (a)		72,297,260
		Internet Traffic Management Equipment
	2,568,000	Infinera (a)		50,512,560
		Optical Networking Equipment
	1,619,000	CalAmp (a)		26,211,610
		Machine-to-machine Communications
				149,021,430
		> Financial Processors 0.9%
	1,261,000	Global Payments		115,608,480
		Credit Card Processor
	1,600,000	Liquidity Services (a)(b)		15,808,000
		E-Auctions for Surplus & Salvage Goods
				131,416,480
		> Semiconductors & Related Equipment 0.7%
	4,467,000	Atmel		36,763,410
		Microcontrollers, Radio Frequency & Memory Semiconductors
	367,000	Littelfuse		36,476,130
		Little Fuses
	427,000	Monolithic Power Systems		22,481,550
		High Performance Analog & Mixed Signal Integrated Circuits
	2,500,000	Rubicon Technology (a)(b)(c)		9,850,000
		Producer of Sapphire for the Lighting, Electronics & Automotive Industries
				105,571,090
		> Cable TV 0.7%
	800,000	Liberty Global Series A (a)		41,176,000

Number of Shares			Value
	366,000	Liberty Global Series C (a)	$	18,230,460
		Cable TV Franchises Outside of the United States
	1,154,000	Discovery Communications Series C (a)		34,014,150
		Cable TV Programming
				93,420,610
		> Contract Manufacturing 0.5%
	3,100,000	Sanmina (a)		74,989,000
		Electronic Manufacturing Services
		> Entertainment Programming 0.5%
	1,250,000	IMAX (Canada) (a)		42,137,500
		IMAX Movies, Theater Equipment & Theater Joint Ventures
	5,500,000	Zee Entertainment Enterprises (India)		30,033,135
		Indian Programmer of Pay Television Content
				72,170,635
		> Electronics Distribution 0.5%
	1,621,000	Avnet		72,134,500
		Electronic Components Distribution
		> Advertising 0.3%
	725,000	Lamar Advertising		42,970,750
		Outdoor Advertising
Information: Total				4,090,708,776
Industrial Goods & Services 23.4%
		> Machinery 15.3%
	6,910,000	Ametek		363,051,400
		Aerospace/Industrial Instruments
	7,952,000	Donaldson (b)		299,869,920
		Industrial Air Filtration
	3,034,000	Nordson		237,683,560
		Dispensing Systems for Adhesives & Coatings
	3,514,750	HEICO (b)		174,120,715
		FAA-approved Aircraft Replacement Parts
	2,027,000	Moog (a)(b)		152,126,350
		Motion Control Products for Aerospace, Defense & Industrial Markets
	2,982,000	Generac (a)		145,193,580
		Standby Power Generators
	946,000	WABCO Holdings (a)		116,244,480
		Truck & Bus Component Supplier
	1,486,000	Toro		104,198,320
		Turf Maintenance Equipment
	2,100,000	Oshkosh Corporation		102,459,000
		Specialty Truck Manufacturer
	968,200	Middleby (a)		99,385,730
		Manufacturer of Cooking Equipment
	1,021,000	Wabtec		97,005,210
		Freight & Transit Component Supplier
	2,592,000	Kennametal		87,324,480
		Consumable Cutting Tools

Number of Shares			Value
		> Machinery—continued
	846,000	Pall	$	84,929,940
		Life Science, Water & Industrial Filtration
	1,489,000	ESCO Technologies (b)		58,041,220
		Industrial Filtration & Advanced Measurement Equipment
	957,721	Dorman Products (a)(c)		47,646,620
		Aftermarket Auto Parts Distributor
				2,169,280,525
		> Other Industrial Services 2.5%
	7,481,000	LKQ (a)		191,214,360
		Alternative Auto Parts Distribution
	1,800,000	Expeditors International of Washington		86,724,000
		International Freight Forwarder
	1,500,000	Forward Air		81,450,000
		Freight Transportation Between Airports
				359,388,360
		> Construction 1.6%
	96,000	NVR (a)		127,551,360
		Homebuilder
	626,000	Allegion		38,292,420
		Mechanical & Electronic Security Systems
	2,865,200	PGT (a)(b)		32,018,610
		Wind Resistant Windows & Doors
	660,000	Fortune Brands Home & Security		31,336,800
		Home Building Supplies & Small Locks
				229,199,190
		> Industrial Distribution 1.4%
	1,553,000	WESCO International (a)		108,539,170
		Industrial Distributor
	853,000	Airgas		90,511,830
		Industrial Gas Distributor
				199,051,000
		> Electrical Components 1.2%
	726,000	Acuity Brands		122,084,160
		Commercial Lighting Fixtures
	1,983,829	Thermon (a)(b)		47,750,764
		Global Engineered Thermal Solutions
				169,834,924
		> Industrial Materials & Specialty Chemicals 0.7%
	1,610,000	Drew Industries (b)		99,079,400
		RV & Manufactured Home Components
		> Outsourcing Services 0.7%
	3,400,000	Quanta Services (a)		97,002,000
		Electrical Transmission & Pipeline Contracting Services
Industrial Goods & Services: Total				3,322,835,399

Number of Shares			Value
Finance 12.1%
		> Banks 4.3%
	9,414,000	Associated Banc-Corp (b)	$	175,100,400
		Midwest Bank
	2,027,000	BOK Financial (c)		124,092,940
		Tulsa-based Southwest Bank
	840,000	SVB Financial Group (a)		106,713,600
		Bank to Venture Capitalists
	2,420,000	MB Financial		75,770,200
		Chicago Bank
	1,730,000	Hancock Holding		51,657,800
		Gulf Coast Bank
	1,163,480	Sandy Spring Bancorp		30,518,081
		Baltimore & Washington, D.C. Bank
	4,296,286	First Busey		28,742,153
		Illinois Bank
	3,136,500	TrustCo Bank		21,579,120
		New York State Bank
				614,174,294
		> Brokerage & Money Management 3.5%
	7,368,774	SEI Investments		324,889,246
		Mutual Fund Administration & Investment Management
	3,463,508	Eaton Vance		144,220,473
		Specialty Mutual Funds
	11,000,000	Sprott (Canada) (c)		23,449,528
		Asset Manager Focused on Resources, Particularly Gold & Silver
				492,559,247
		> Insurance 2.1%
	7,300,000	CNO Financial Group		125,706,000
		Life, Long-term Care & Medical Supplement Insurance
	2,000,000	Allied World Assurance Company Holdings		80,800,000
		Commercial Lines Insurance/Reinsurance
	910,000	HCC Insurance Holdings		51,569,700
		Specialty Insurance
	800,000	RLI		41,928,000
		Specialty Insurance
				300,003,700
		> Finance Companies 0.9%
	787,422	World Acceptance (a)(b)(c)		57,418,812
		Personal Loans
	1,345,000	McGrath Rentcorp (b)		44,263,950
		Mini-rental Conglomerate
	839,000	CAI International (a)		20,614,230
		International Container Leasing
				122,296,992
		> Credit Cards 0.6%
	863,000	WEX (a)		92,651,680
		Card Processor
		> Diversified Financial Companies 0.6%
	3,875,000	Leucadia National		86,373,750
		Holding Company

COLUMBIA ACORN® FUND

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Specialized Finance 0.1%
	195,201	MSCI	$	11,967,773
		Investment Decision Support Tools
Finance: Total				1,720,027,436
Health Care 11.4%
		> Biotechnology & Drug Delivery 4.3%
	1,950,318	Synageva BioPharma (a)(b)(c)		190,214,515
		Biotech Focused on Orphan Diseases
	1,704,000	Ultragenyx Pharmaceutical (a)		105,801,360
		Biotech Focused on "Ultra-Orphan" Drugs
	2,548,000	Seattle Genetics (a)		90,071,800
		Antibody-based Therapies for Cancer
	269,200	Intercept Pharmaceuticals (a)(c)		75,919,784
		Biotech Developing Drugs for Several Diseases
	2,140,400	Celldex Therapeutics (a)(c)		59,652,948
		Biotech Developing Drugs for Cancer
	2,523,900	Sarepta Therapeutics (a)(b)(c)		33,517,392
		Biotech Focused on Rare Diseases
	302,300	Alnylam Pharmaceuticals (a)		31,566,166
		Biotech Developing Drugs Primarily for Rare Diseases
	275,000	Agios Pharmaceuticals (a)(c)		25,932,500
		Biotech Focused on Cancer & Orphan Diseases
	359,944	MicroDose Therapeutx Contingent Value Rights (a)(d)(e)		395,938
		Drug Inhaler Development
				613,072,403
		> Medical Supplies 3.3%
	4,909,800	Cepheid (a)(b)		279,367,620
		Molecular Diagnostics
	1,169,200	Bio-Techne		117,259,068
		Maker of Consumables & Systems for the Life Science Market
	291,100	Henry Schein (a)		40,643,382
		Distributor of Dental, Vet & Medical Products
	1,375,400	VWR (a)		35,746,646
		Distributor of Lab Supplies
				473,016,716
		> Health Care Services 1.7%
	1,549,500	Medidata Solutions (a)		75,987,480
		Cloud-based Software for Drug Studies
	1,647,700	HealthSouth		73,091,972
		Inpatient Rehabilitation Facilities & Home Health Care
	1,239,000	Envision Healthcare Holdings (a)		47,515,650
		Provider of Health Care Outsourcing Services
	2,746,200	Allscripts Healthcare Solutions (a)		32,844,552
		Health Care IT
	487,818	Castlight Health (a)		3,785,467
		Provider of Cloud-based Software for Managing Health Care Costs
				233,225,121

Number of Shares			Value
		> Medical Equipment & Devices 1.1%
	1,729,500	Wright Medical Group (a)	$	44,621,100
		Foot & Ankle Replacement
	460,900	Sirona Dental Systems (a)		41,476,391
		Manufacturer of Dental Equipment
	595,000	Abaxis		38,145,450
		Instruments & Tests for Vet & Medical Markets
	513,000	Align Technology (a)		27,591,705
		Invisalign System to Correct Malocclusion (Crooked Teeth)
				151,834,646
		> Pharmaceuticals 1.0%
	3,048,000	Akorn (a)		144,810,480
		Developer, Manufacturer & Distributor of Specialty Generic Drugs
Health Care: Total				1,615,959,366
Consumer Goods & Services 11.1%
		> Retail 2.9%
	880,145	Fossil (a)		72,567,955
		Watch Designer & Retailer
	791,839	Casey's General Stores		71,344,694
		Owner/Operator of Convenience Stores
	1,492,000	The Fresh Market (a)		60,634,880
		Specialty Food Retailer
	595,200	Williams-Sonoma		47,443,392
		Home Goods & Furnishing Retailer
	786,900	Burlington Stores (a)		46,757,598
		Off-price Apparel Retailer
	771,056	Shutterfly (a)		34,882,573
		Internet Photo-centric Retailer
	508,000	Urban Outfitters (a)		23,190,200
		Multi-channel Apparel & Accessory Retailer
	533,500	DSW		19,675,480
		Branded Footwear Retailer
	642,492	Michaels Stores (a)		17,385,834
		Craft & Hobby Specialty Retailer
	2,100,000	Gaiam (a)(b)		15,309,000
		Promoter of Healthy Living through Catalogs, E-Commerce & Gaiam TV
	425,245	Zulily (a)(c)		5,523,933
		E-Commerce Retailer Offering Flash Sale Events
				414,715,539
		> Travel 2.8%
	2,450,000	Avis Budget Group (a)		144,586,750
		Car Rental Company
	895,600	Vail Resorts		92,622,952
		Ski Resort Operator & Developer
	2,142,000	HomeAway (a)		64,624,140
		Vacation Rental Online Marketplace
	2,531,000	Hertz (a)		54,872,080
		U.S. Rental Car Operator
	729,483	Choice Hotels		46,737,976
		Franchisor of Budget Hotel Brands
				403,443,898

Number of Shares			Value
		> Consumer Goods Distribution 1.6%
	1,444,000	Pool	$	100,733,440
		Swimming Pool Supplies & Equipment Distributor
	1,286,000	United Natural Foods (a)		99,073,440
		Distributor of Natural/Organic Foods to Grocery Stores
	863,000	The Chefs' Warehouse (a)		19,357,090
		Distributor of Specialty Foods to Fine Dining Restaurants
				219,163,970
		> Restaurants 1.3%
	950,000	Papa John's International		58,719,500
		Franchisor of Pizza Restaurants
	858,000	Fiesta Restaurant Group (a)		52,338,000
		Owner/Operator of Two Restaurant Chains: Pollo Tropical & Taco Cabana
	403,000	Domino's Pizza		40,521,650
		Franchisor of Pizza Restaurants
	650,000	Popeyes Louisiana Kitchen (a)		38,883,000
		Popeyes Restaurants
				190,462,150
		> Other Durable Goods 1.2%
	2,224,284	Select Comfort (a)		76,671,069
		Specialty Mattresses
	2,732,952	Gentex		50,013,022
		Manufacturer of Auto Parts
	500,000	Cavco Industries (a)(b)		37,530,000
		Manufactured Homes
				164,214,091
		> Furniture & Textiles 0.7%
	2,836,000	Knoll (b)		66,447,480
		Office Furniture
	540,000	Caesarstone (Israel)		32,783,400
		Quartz Countertops
				99,230,880
		> Apparel 0.3%
	456,000	PVH		48,591,360
		Apparel Wholesaler & Retailer
		> Other Consumer Services 0.3%
	994,000	Blackhawk Network (a)		35,336,700
		Third-party Distributor of Prepaid Content, Mostly Gift Cards
		> Food & Beverage —%
	1,493,770	GLG Life Tech (Canada) (a)		371,511
		Producer of an All-natural Sweetener Extracted from the Stevia Plant
Consumer Goods & Services: Total				1,575,530,099
Other Industries 6.5%
		> Real Estate 3.8%
	717,000	Federal Realty		105,549,570
		Shopping Centers & Mixed Use Projects
	1,467,000	Extra Space Storage		99,125,190
		Self Storage Facilities

Number of Shares			Value
	2,450,000	EdR (b)	$	86,681,000
		Student Housing
	1,320,000	Post Properties		75,147,600
		Multifamily Properties
	190,000	Amerco		62,776,000
		North American Moving & Storage King
	325,000	Jones Lang LaSalle		55,380,000
		Real Estate Services
	2,150,000	Terreno Realty (b)		49,020,000
		Industrial Properties
				533,679,360
		> Transportation 1.9%
	2,650,000	Rush Enterprises, Class A (a)(b)		72,504,000
	550,000	Rush Enterprises, Class B (a)(b)		13,596,000
		Truck Sales & Service
	669,000	JB Hunt Transport Services		57,129,255
		Truck & Intermodal Carrier
	720,000	Kirby (a)		54,036,000
		Operator of U.S. (Jones Act) Liquid Tank Barges
	1,800,000	Heartland Express		42,768,000
		Regional Trucker
	380,000	Genesee & Wyoming (a)		36,647,200
		Short-line Operator
				276,680,455
		> Regulated Utilities 0.8%
	1,600,000	Eversource Energy		80,832,000
		Regulated Electric Utility
	577,000	Wisconsin Energy		28,561,500
		Wisconsin Utility
				109,393,500
Other Industries: Total				919,753,315
Energy & Minerals 3.6%
		> Oil & Gas Producers 1.9%
	1,037,000	Carrizo Oil & Gas (a)		51,487,050
		Oil & Gas Producer
	420,000	Cimarex Energy		48,337,800
		Oil & Gas Producer in Texas, New Mexico & Oklahoma
	732,000	Energen Corporation		48,312,000
		Oil & Gas Producer with Natural Gas Utility
	778,000	SM Energy		40,207,040
		Oil & Gas Producer
	501,000	PDC Energy (a)		27,074,040
		Oil & Gas Producer in the United States
	1,550,000	Rosetta Resources (a)		26,381,000
		Oil & Gas Producer Exploring in Texas
	281,000	Clayton Williams (a)		14,227,030
		Oil & Gas Producer
	107,561,000	ShaMaran Petroleum (Iraq) (a)(b)		7,643,196
		Oil Exploration & Production in Kurdistan

COLUMBIA ACORN® FUND

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Oil & Gas Producers—continued
	67,500,000	Petromanas (Canada) (a)(b)(c)	$	2,664,719
		Exploring for Oil in Albania
	24,115,500	Canadian Overseas Petroleum (Canada) (a)(b)		1,570,825
	8,400,000	Canadian Overseas Petroleum (Canada) (a)(b)(d)		519,798
		Oil & Gas Exploration Offshore West Africa
	2,600,000	Petrodorado Energy (Colombia) (a)(b)		205,282
		Oil & Gas Exploration & Production in Colombia, Peru & Paraguay
				268,629,780
		> Oil Services 0.8%
	1,797,579	ShawCor (Canada)		49,958,376
		Oil & Gas Pipeline Products
	780,000	Gulfport Energy (a)		35,809,800
		Oil & Gas Producer Focused on Utica Shale in Ohio
	1,470,000	Hornbeck Offshore (a)		27,650,700
		Supply Vessel Operator in Gulf of Mexico
				113,418,876
		> Mining 0.8%
	423,000	Core Labs (Netherlands) (c)		44,199,270
		Oil & Gas Reservoir Consulting
	6,697,200	Kirkland Lake Gold (Canada) (a)(b)(c)		28,765,361
		Gold Mining
	3,500,000	Alamos Gold (Canada)		20,504,520
		Gold Mining
	9,014,700	Argonaut Gold (Canada) (a)(b)		12,526,842
		Gold & Silver Mining
	3,412,300	Silvercrest Mines (a)		3,744,895
		Gold & Silver Mining
	3,000,000	Kaminak Gold (a)(c)		2,131,776
		Exploration Stage Canadian Gold Miner
				111,872,664

Number of Shares			Value
		> Agricultural Commodities 0.1%
	1,306,818	Union Agriculture Group (Uruguay) (a)(d)(e)	$	14,231,248
		Farmland Operator in Uruguay
Energy & Minerals: Total				508,152,568
Total Equities: 97.0% (Cost: $7,228,403,959)				13,752,966,959	(f)
Short-Term Investments 3.2%
	280,000,000	JPMorgan U.S. Government Money Market Fund, IM Shares (7 day yield of 0.01%)		280,000,000
	177,215,101	JPMorgan U.S. Government Money Market Fund, Agency Shares (7 day yield of 0.01%)		177,215,101
Total Short-Term Investments: 3.2% (Cost: $457,215,101)				457,215,101
Securities Lending Collateral 1.7%
	236,439,798	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (g)		236,439,798
Total Securities Lending Collateral: 1.7% (Cost: $236,439,798)				236,439,798
Total Investments: 101.9% (Cost: $7,922,058,858)(h)				14,446,621,858	(i)
Obligation to Return Collateral for Securities Loaned: (1.7)%				(236,439,798	)
Cash and Other Assets Less Liabilities: (0.2)%				(27,973,810	)
Net Assets: 100.0%			$	14,182,208,250

ADR - American Depositary Receipts

> Notes to Statement of Investments

(a) Non-income producing security.

(b) An affiliated person of the Fund, as defined in the Investment Company Act of 1940, may include any company in which the Fund owns five percent or more of its outstanding voting shares. Holdings and transactions in these affiliated companies during the period ended March 31, 2015, are as follows:

Security	Balance of Shares Held 12/31/14		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 3/31/15		Value		Dividend
Donaldson		7,952,000		-		-		7,952,000	$	299,869,920	$	1,312,080
Cepheid		5,350,800		-		441,000		4,909,800		279,367,620		-
Nordson (1)		3,130,000		-		96,000		3,034,000		237,683,560		667,480
Synageva BioPharma		2,419,209		-		468,891		1,950,318		190,214,515		-
Associated Banc-Corp		9,000,000		414,000		-		9,414,000		175,100,400		941,400
HEICO		3,626,750		-		112,000		3,514,750		174,120,715		-
Moog		2,456,000		-		429,000		2,027,000		152,126,350		-

> Notes to Statement of Investments

Security	Balance of Shares Held 12/31/14		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 3/31/15		Value		Dividend
Generac (1)		3,632,000		-		650,000		2,982,000	$	145,193,580	$	-
Drew Industries		1,610,000		-		-		1,610,000		99,079,400		3,220,000
EdR		2,450,000		-		-		2,450,000		86,681,000		882,000
Rush Enterprises		3,200,000		-		-		3,200,000		86,100,000		-
Bankrate		6,300,300		949,700		-		7,250,000		82,215,000		-
SPS Commerce		1,330,000		-		254,000		1,076,000		72,199,600		-
Vonage		14,044,775		455,225		-		14,500,000		71,195,000		-
Knoll		3,366,000		-		530,000		2,836,000		66,447,480		361,264
Virtusa		1,658,000		-		88,000		1,570,000		64,966,600		-
ESCO Technologies		1,948,000		-		459,000		1,489,000		58,041,220		119,120
World Acceptance		808,343		-		20,921		787,422		57,418,812		-
GTT Communications		1,950,000		651,000		-		2,601,000		49,106,880		-
Terreno Realty		2,150,000		-		-		2,150,000		49,020,000		-
Thermon		1,940,094		43,735		-		1,983,829		47,750,764		-
McGrath Rentcorp		1,580,000		-		235,000		1,345,000		44,263,950		387,100
inContact		3,741,000		-		-		3,741,000		40,776,900		-
Navigant Consulting		4,128,523		-		1,028,523		3,100,000		40,176,000		-
Cavco Industries		500,000		-		-		500,000		37,530,000		-
Sarepta Therapeutics		2,523,900		-		-		2,523,900		33,517,392		-
PGT		3,592,200		-		727,000		2,865,200		32,018,610		-
Kirkland Lake Gold		6,347,100		350,100		-		6,697,200		28,765,361		-
Hackett Group		2,903,719		-		203,719		2,700,000		24,138,000		-
Boingo Wireless		2,800,000		100,000		-		2,900,000		21,866,000		-
CAI International (1)		1,500,000		-		661,000		839,000		20,614,230		-
Liquidity Services		1,600,000		-		-		1,600,000		15,808,000		-
Gaiam		2,100,000		-		-		2,100,000		15,309,000		-
Argonaut Gold		9,014,700		-		-		9,014,700		12,526,842		-
Rubicon Technology		2,500,000		-		-		2,500,000		9,850,000		-
Towerstream		4,000,000		-		-		4,000,000		8,640,000		-
ShaMaran Petroleum		28,962,000		78,599,000				107,561,000		7,643,196		-
Audience		2,150,000		-		506,000		1,644,000		7,463,760		-
Petromanas		67,500,000		-		-		67,500,000		2,664,719		-
Canadian Overseas Petroleum		32,515,500		-		-		32,515,500		2,090,623		-
Petrodorado Energy		2,600,000		-		-		2,600,000		205,282		-
Allied Nevada Gold (1)		7,103,513		-		7,103,513		-		-		-
Amber Road (1)		2,000,000		-		2,000,000		-		-		-
Boulder Brands (1)		3,484,000		-		3,484,000		-		-		-
E2Open (1)		2,575,000		-		2,575,000		-		-		-
Marlin Business Services (1)		902,210		-		902,210		-		-		-
RGS Energy (1)		5,000,000		-		5,000,000		-		-		-
Total of Affiliated Transactions		283,945,636		81,562,760		27,974,777		337,533,619	$	2,949,766,281	$	7,890,444

(1) At March 31, 2015, the Fund owned less than five percent of the company's outstanding voting shares.

The aggregate cost and value of these companies at March 31, 2015, was $1,518,703,816 and $2,546,274,911, respectively. Investments in affiliated companies represented 17.95% of the Fund's total net assets at March 31, 2015.

(c) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $226,593,324.

(d) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at fair value determined in good faith under consistently applied procedures established by the Fund's Board of Trustees. At March 31, 2015, the market value of these securities amounted to $15,146,984, which represented 0.11% of total net assets. Additional information on these securities is as follows:

Security	Acquisition Dates	Shares/Units		Cost		Value
Union Agriculture Group	12/8/10-6/27/12		1,306,818	$	15,000,000	$	14,231,248
Canadian Overseas Petroleum	11/24/10		8,400,000		3,591,152		519,798
MicroDose Therapeutx Contingent Value Rights	8/14/13		359,944		-		395,938
				$	18,591,152	$	15,146,984

(e) Illiquid security.

COLUMBIA ACORN® FUND

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

(f) On March 31, 2015, the market value of foreign securities represented 2.20% of total net assets. The Fund's foreign portfolio was diversified as follows:

Country	Value		Percentage of Net Assets
Canada	$	182,468,980		1.30
Netherlands		44,199,270		0.31
Israel		32,783,400		0.23
India		30,033,135		0.21
Uruguay		14,231,248		0.10
Iraq		7,643,196		0.05
Colombia		205,282		0.00	*
Total Foreign Portfolio	$	311,564,511		2.20

* Rounds to zero.

(g) Investment made with cash collateral received from securities lending activity.

(h) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $7,922,058,858 and net unrealized appreciation was $6,524,563,000 consisting of gross unrealized appreciation of $6,888,584,428 and gross unrealized depreciation of $364,021,428.

(i) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

Fair Value Measurements

Various inputs are used in determining the value of the Fund's investments, following the input prioritization hierarchy established by accounting principles generally accepted in the United States of America (GAAP). These inputs are summarized in the three broad levels listed below:

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

• Level 3 – prices determined using significant unobservable inputs where quoted prices or observable inputs are unavailable or less reliable (including management's own assumptions about the factors market participants would use in pricing an investment)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Examples of the types of securities in which the Fund would typically invest and how they are classified within this hierarchy are as follows. Typical Level 1 securities include exchange traded domestic equities, mutual funds whose NAVs are published each day and exchange traded foreign equities that are not statistically fair valued. Typical Level 2 securities include exchange traded foreign equities that are statistically fair valued, forward foreign currency exchange contracts and short-term investments valued at amortized cost. Additionally, securities fair valued by the Valuation Committee (the Committee) of the Fund's Board of Trustees (the Board) that rely on significant observable inputs are also included in Level 2. Typical Level 3 securities include any security fair valued by the Committee that relies on significant unobservable inputs.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

The Committee meets as necessary, and no less frequently than quarterly, to determine fair values for securities for which market quotations are not readily available or for which the investment manager believes that available market quotations are unreliable, to review the appropriateness of the Trust's Portfolio Pricing Policy and the pricing procedures of the investment manager (the Policies), and to review the continuing appropriateness of the current value of any security subject to the Policies. The Policies address, among other things: circumstances under which market quotations will be deemed readily available; selection of third party pricing vendors; appropriate pricing methodologies; events that require fair valuation and fair value techniques; circumstances under which securities will be deemed to pose a potential for stale pricing, including when securities are illiquid, restricted, or in default; and certain delegations of authority to determine fair values to the Fund's investment manager. The Committee may also meet to discuss additional valuation matters, which may include review of back-testing results, review of time-sensitive information or approval of other valuation related actions, and to review the appropriateness of the Policies.

For investments categorized as Level 3, the significant unobservable inputs used in the fair value measurement of the Funds' securities may include: (i) data specific to the issuer or comparable issuers, (ii) general market or specific sector news and (iii) quoted prices and specific or similar security transactions. The Committee considers this data and any changes from prior periods in order to assess the reasonableness of observable and unobservable inputs, any assumptions or internal models used to value those securities and changes in fair value. Significant changes in any of these factors could result in lower or higher fair value measurements. Various factors impact the frequency of monitoring (which may occur as often as daily), however the Committee may determine that changes to inputs, assumptions and models are not required with the same frequency.

> Notes to Statement of Investments

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Information	$	4,060,675,641	$	30,033,135	$	—	$	4,090,708,776
Industrial Goods & Services		3,322,835,399		—		—		3,322,835,399
Finance		1,720,027,436		—		—		1,720,027,436
Health Care		1,615,563,428		—		395,938		1,615,959,366
Consumer Goods & Services		1,575,530,099		—		—		1,575,530,099
Other Industries		919,753,315		—		—		919,753,315
Energy & Minerals		493,401,522		519,798		14,231,248		508,152,568
Total Equities		13,707,786,840		30,552,933		14,627,186		13,752,966,959
Total Short-Term Investments		457,215,101		—		—		457,215,101
Total Securities Lending Collateral		236,439,798		—		—		236,439,798
Total Investments	$	14,401,441,739	$	30,552,933	$	14,627,186	$	14,446,621,858

The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sale price on the foreign exchange or market on which they trade. The Fund may use a statistical fair valuation model, in accordance with the policy adopted by the Board, provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Securities acquired via private placement that have a holding period or an extended settlement period are valued at a discount to the same shares that are trading freely on the market. These discounts are determined by the investment manager's experience with similar securities or situations. Factors may include, but are not limited to, trade volume, shares outstanding and stock price.

There were no transfers of financial assets between levels during the period.

The Fund does not hold any significant investments (greater than one percent of net assets) categorized as Level 3.

Certain securities classified as Level 3 are valued at fair value, using a market approach, as determined in good faith under consistently applied procedures established by and under the general supervision of the Board. To determine fair value for these securities, for which no market exists, the Committee utilizes the valuation technique it deems most appropriate in the circumstances, using some unobservable inputs, which may include, but are not limited to estimated earnings of the company and the position of the security within the company's capital structure. The Committee also may use some observable inputs, which may include, but are not limited to, trades of similar securities and market multiples derived from a set of comparable companies. Significant increases or decreases to any of these inputs could result in a significantly lower or higher fair value measurement.

COLUMBIA ACORN INTERNATIONAL®

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Asia
> Japan
Aeon Financial Service		1,205,000		1,600,000
Aeon Mall		2,004,900		2,710,000
Glory		1,430,000		1,798,600
Hikari Tsushin		255,800		313,200
IHI		0		4,235,000
Kaken Pharmaceutical		0		686,800
Milbon		571,080		698,480
NGK Insulators		1,600,000		2,700,000
NGK Spark Plug		1,170,000		1,440,000
Nippon Shokubai		0		2,066,000
NOF		4,872,000		5,311,000
OBIC		688,000		772,000
Omron		462,000		512,000
Otsuka		419,300		629,900
Recruit Holdings		0		1,225,000
> Taiwan
Chroma Ate		6,427,000		7,611,000
Far EasTone Telecom		12,570,000		14,140,000
Hermes Microvision		174,750		211,750
Lite-On Technology		5,594,881		10,016,881
President Chain Store		7,306,000		9,100,000
Voltronic Power		0		1,000,000
> India
Bharti Infratel		0		6,229,667
Container Corporation of India		0		1,204,602
> Singapore
Mapletree Commercial Trust		53,724,268		55,000,000
Singapore Exchange		6,596,000		11,000,000
> Korea
CJ Hellovision		0		578,438
KT&G		349,317		536,317
LF Corp		758,028		1,119,428
Nongshim		94,000		145,900
> China
AMVIG Holdings		35,119,000		47,500,000
China Everbright International		0		28,645,000
Sihuan Pharmaceuticals		83,100,000		90,360,000
Sino Biopharmaceutical		0		23,671,000
> Hong Kong
Vitasoy International		5,818,000		9,347,000
> Indonesia
Link Net		37,000,000		43,000,000
Mayora Indah		5,600,000		6,000,000

	Number of Shares
	12/31/14		3/31/15
> Philippines
Melco Crown (Philippines) Resorts		78,170,000		90,000,000
Universal Robina		2,114,550		3,106,980
Europe
> United Kingdom
Abcam		4,550,000		4,800,000
Aggreko		1,300,000		1,980,000
Cable and Wireless		35,245,747		45,000,000
Halfords		3,277,885		4,372,390
Polypipe		6,534,800		7,430,000
> Sweden
Modern Times Group		0		1,137,000
Recipharm		0		979,403
> Germany
MTU Aero Engines		465,000		608,000
> Spain
Distribuidora Internacional de Alimentación		7,828,000		10,110,000
> France
Eutelsat		798,001		1,110,000
> Netherlands
Brunel		1,140,000		1,201,000
Gemalto		237,700		324,700
Vopak		404,124		718,124
> Italy
Industria Macchine Automatiche		0		385,950
Other Countries
> Canada
Baytex		1,108,857		1,358,857
DeeThree Exploration		3,298,377		4,490,105
Keyera		0		363,000
Prairie Sky Royalty		0		1,010,000
Vermilion Energy		0		898,000
> Australia
Spotless		42,700,000		46,578,144
> United States
Cimarex Energy		0		350,000
> Egypt
Commercial International Bank of Egypt		0		3,119,000
Latin America
> Brazil
Linx		1,184,000		1,400,000
Localiza Rent A Car		2,802,000		3,500,000

	Number of Shares
	12/31/14		3/31/15
Sales
Asia
> Japan
Aica Kogyo		1,246,000		1,012,000
Ariake Japan		1,129,000		876,300
Disco		434,400		292,400
Hoshizaki Electric		420,000		390,000
Japan Airport Terminal		960,000		600,000
Lifenet Insurance		488,700		0
Makita		600,000		258,000
Misumi Group		960,000		650,000
MonotaRO		575,600		352,600
Nabtesco		1,110,000		886,900
Nippon Kayaku		3,260,000		3,143,000
Nippon Paint Holdings		970,000		624,000
Park24		2,150,000		1,960,000
Shimano		208,000		0
Toyo Suisan Kaisha		792,900		370,900
> Taiwan
Largan Precision		364,000		293,000
> India
United Breweries		2,085,000		1,850,000
> Korea
Cheil Industries		122,726		0
Coway		295,580		0
Grand Korea Leisure		591,876		475,576
Paradise		974,261		0
Soulbrain		86,274		0
> China
CIMC Enric		17,890,000		0
WuXi PharmaTech - ADR		2,500,000		850,000
> Hong Kong
MGM China Holdings		7,247,000		0
Sa Sa International		33,757,000		25,223,000
> Indonesia
Surya Citra Media		54,535,800		11,854,300
> Philippines
Puregold Price Club		35,000,000		31,000,000
Robinsons Retail Holdings		17,000,000		16,000,000
Security Bank		5,000,000		0
> Malaysia
7-Eleven Malaysia Holdings		46,980,000		43,839,000
Aeon		22,609,800		17,441,500
Europe
> United Kingdom
Babcock International		4,000,000		3,300,000
Jardine Lloyd Thompson Group		3,950,000		2,630,000

	Number of Shares
	12/31/14		3/31/15
Rightmove		1,338,000		872,000
Smith & Nephew		1,510,000		1,280,000
> Sweden
Hexagon		2,168,522		1,723,394
Swedish Match		1,580,000		856,000
> Germany
Rational		130,000		117,000
Wirecard		1,663,000		1,350,000
> Spain
Viscofan		794,000		671,000
> France
Eurofins Scientific		146,000		90,000
> Netherlands
Aalberts Industries		2,491,770		2,103,770
> Switzerland
Partners Group		263,500		213,500
> Denmark
Jyske Bank		709,000		0
> Norway
Subsea 7		1,321,000		0
> Italy
Pirelli		2,787,000		1,909,000
Other Countries
> Canada
Black Diamond Group		551,976		0
Canadian Energy Services & Technology		3,622,000		0
CCL Industries		862,772		800,772
Horizon North Logistics		1,901,514		0
Trilogy Energy		766,000		0
> South Africa
Coronation Fund Managers		13,858,792		13,683,594
Naspers		777,188		493,188
Rand Merchant Insurance		20,179,300		19,045,300
> Australia
Amcor		6,725,000		4,270,000
Austbrokers		2,196,850		1,217,356
Domino's Pizza Enterprises		2,978,993		2,428,257
IAG		10,600,000		5,260,000
MMA Offshore		10,912,000		0
> United States
Chart Industries		225,000		0
FMC Technologies		168,213		0
Rowan		685,900		0
Textainer Group Holdings		1,272,297		933,297

COLUMBIA ACORN INTERNATIONAL®

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED), CONTINUED

	Number of Shares
	12/31/14		3/31/15
Sales (continued)
Latin America
> Brazil
Beadell Resources		37,336,982		3,421,215
> Mexico
Genomma Lab International		10,184,000		0
Gruma		2,200,000		0

COLUMBIA ACORN INTERNATIONAL®

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 96.0%
Asia 46.2%
		> Japan 22.1%
	2,700,000	NGK Insulators	$	57,527,649
		Ceramic Products for Auto, Power & Electronics
	2,978,600	Kansai Paint		54,209,818
		Paint Producer in Japan, India, China & Southeast Asia
	2,710,000	Aeon Mall		53,666,439
		Suburban Shopping Mall Developer, Owner & Operator
	1,798,600	Glory		50,087,269
		Currency Handling Systems & Related Equipment
	3,850,800	Ushio		47,732,799
		Industrial Light Sources
	1,050,000	FamilyMart		43,993,378
		Convenience Store Operator
	1,301,200	Benesse		40,933,231
		Education Service Provider
	1,600,000	Aeon Financial Service		40,361,893
		Diversified Consumer-related Finance Company in Japan
	28,000	Orix JREIT		40,103,071
		Diversified REIT
	1,960,000	Park24		40,101,097
		Parking Lot Operator
	2,728,000	Santen Pharmaceutical		39,790,123
		Specialty Pharma (Ophthalmic Medicine)
	5,311,000	NOF		39,397,331
		Specialty Chemicals, Life Science & Rocket Fuels
	3,143,000	Nippon Kayaku		39,352,399
		Functional Chemicals, Pharmaceuticals & Auto Safety Systems
	1,440,000	NGK Spark Plug		38,655,375
		Automobile Parts
	1,225,000	Recruit Holdings		38,221,789
		Recruitment & Media Services
	600,000	Japan Airport Terminal		36,285,663
		Airport Terminal Operator at Haneda
	277,620	Hirose Electric		35,743,745
		Electrical Connectors
	752,800	Kintetsu World Express		33,836,654
		Airfreight Logistics
	6,149	Kenedix Office Investment		33,739,618
		Tokyo Mid-size Office REIT
	772,000	OBIC		32,736,918
		Computer Software
	930,000	JIN (a)		32,205,104
		Eyeglasses Retailer
	1,600,000	OSG		31,115,701
		Consumable Cutting Tools
	1,470,000	Suruga Bank		30,527,007
		Regional Bank

Number of Shares			Value
	2,066,000	Nippon Shokubai	$	30,240,518
		Producer of Acrylic Acid & Super Absorbent Polymers used in Disposable Diapers
	746,500	Ezaki Glico		30,178,682
		Confectionary, Ice Cream & Dairy Products
	1,402,000	Tamron (b)		30,165,507
		Camera Lenses
	876,300	Ariake Japan		30,082,564
		Commercial Soup & Sauce Extracts
	2,736,000	Moshi Moshi Hotline		29,853,954
		Call Center Operator
	292,400	Disco		29,833,863
		Semiconductor Dicing & Grinding Equipment
	2,000,000	Toto		29,697,920
		Toilets & Bathroom Fittings
	8,340,000	Aozora Bank		29,561,634
		Commercial Bank
	1,580,000	Daiseki		28,490,844
		Waste Disposal & Recycling
	629,900	Otsuka		26,843,300
		One-stop IT Services & Office Supplies Provider
	650,000	Misumi Group		26,195,854
		Industrial Components Distributor
	886,900	Nabtesco		25,621,857
		Machinery Components
	390,000	Hoshizaki Electric		25,326,120
		Commercial Kitchen Equipment
	643,000	Nakanishi		25,092,395
		Dental Tools & Machinery
	1,107,000	Stanley Electric		24,987,566
		Automobile Lighting & LED Equipment
	1,600,000	Doshisha		24,833,045
		Consumer Goods Wholesaler
	12,050	Japan Retail Fund		23,944,337
		Largest Retail REIT in Japan
	1,676,000	Rohto Pharmaceutical		23,822,025
		Pharmaceutical, Health & Beauty Products
	5,092	Industrial & Infrastructure Fund		23,700,366
		Industrial REIT in Japan
	783,600	Hamamatsu Photonics		23,619,405
		Optical Sensors for Medical & Industrial Applications
	1,012,000	Aica Kogyo		23,564,882
		Laminated Sheets, Building Materials & Chemical Adhesives
	512,000	Omron		23,065,167
		Electric Components for Factory Automation
	309,000	Rinnai		22,900,276
		Gas Appliances for Home & Commercial Use
	624,000	Nippon Paint Holdings		22,811,414
		Paints for Automotive, Decorative & Industrial Usage
	698,480	Milbon		22,418,639
		Hair Products for Salons

COLUMBIA ACORN INTERNATIONAL®

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Japan—continued
	1,914,500	Asahi Diamond Industrial	$	21,850,149
		Consumable Diamond Tools
	1,753,060	Nihon Parkerizing		21,205,884
		Metal Surface Treatment Chemicals & Processing Service
	313,200	Hikari Tsushin		20,284,592
		Office IT/Mobiles/Insurance Distribution
	835,000	Icom (b)		20,067,394
		Two Way Radio Communication Equipment
	686,800	Kaken Pharmaceutical		19,855,165
		Pharmaceutical & Agrochemical Producer
	4,235,000	IHI		19,801,717
		Industrial Conglomerates
	258,000	Makita		13,369,642
		Power Tools
	370,900	Toyo Suisan Kaisha		13,049,133
		Instant Noodles & Processed Foods
	352,600	MonotaRO (a)		12,770,515
		Online Maintenance, Repair & Operations Goods Distributor in Japan
	1,496	Kenedix Retail REIT		3,471,354
		Retail REIT in Japan
				1,752,901,750
		> Taiwan 4.6%
	9,100,000	President Chain Store		68,396,889
		Convenience Chain Store Operator in Taiwan
	14,140,000	Far EasTone Telecom		34,111,990
		Mobile Operator in Taiwan
	2,081,000	St. Shine Optical		33,498,260
		Disposable Contact Lens Original Equipment Manufacturer
	5,871,000	Novatek Microelectronics		30,299,818
		Display Related Integrated Circuit Designer
	2,300,000	PChome Online		29,871,567
		Taiwanese Internet Retail Company
	293,000	Largan Precision		25,188,620
		Mobile Device Camera Lenses & Modules
	3,761,000	Delta Electronics		23,699,715
		Industrial Automation, Switching Power Supplies & Passive Components
	3,034,686	Advantech		23,075,971
		Industrial PC & Components
	13,516,000	Vanguard International Semiconductor		22,943,033
		Semiconductor Foundry
	1,925,000	Ginko International		22,115,216
		Contact Lens Maker in China
	7,611,000	Chroma Ate		18,886,325
		Automatic Test Systems, Testing & Measurement Instruments
	10,016,881	Lite-On Technology		12,957,953
		Mobile Device, LED & PC Server Component Supplier

Number of Shares			Value
	211,750	Hermes Microvision	$	12,182,406
		E-Beam Inspection Systems for Semiconductor Integrated Circuits
	1,000,000	Voltronic Power		9,900,562
		Uninterruptible Power Supply Products
				367,128,325
		> India 4.0%
	13,478,000	Zee Entertainment Enterprises		73,597,561
		Indian Programmer of Pay Television Content
	3,423,265	Asian Paints		44,411,409
		Indian Paint Company
	6,229,667	Bharti Infratel		38,324,926
		Communications Towers
	90,000	Bosch		36,559,217
		Automotive Parts
	1,204,602	Container Corporation of India		30,474,445
		Railway Cargo Services
	6,095,000	Adani Ports & Special Economic Zone		30,011,065
		Indian West Coast Shipping Port
	920,000	Colgate Palmolive India		29,600,896
		Consumer Products in Oral Care
	1,850,000	United Breweries		29,564,791
		Indian Brewer
				312,544,310
		> Singapore 3.0%
	11,000,000	Singapore Exchange		65,223,007
		Singapore Equity & Derivatives Market Operator
	55,000,000	Mapletree Commercial Trust		64,124,626
		Retail & Office Property Landlord
	13,500,000	Ascendas REIT		25,464,137
		Industrial Property Landlord
	8,500,000	Petra Foods		23,654,304
		Chocolate Manufacturer in Southeast Asia
	17,742,000	CDL Hospitality Trust		22,688,971
		Hotel Owner Operator
	20,865,750	Mapletree Logistics Trust		18,929,470
		Industrial Property Landlord
	15,000,000	Mapletree Industrial Trust		17,254,695
		Industrial Property Landlord
				237,339,210
		> Korea 2.9%
	536,317	KT&G		42,878,289
		Tobacco & Ginseng Products
	249,671	CJ Corp		39,562,070
		Holding Company of Korean Consumer Conglomerate
	631,865	LS Industrial Systems		36,302,491
		Electrical & Automation Equipment
	145,900	Nongshim		32,000,598
		Instant Noodles, Snacks & Bottled Water
	1,119,428	LF Corp		31,943,755
		Apparel Design & Retail
	1,187,900	Cheil Worldwide (c)		25,734,223
		Advertising
	475,576	Grand Korea Leisure (a)		16,189,361
		'Foreigner Only' Casino Group in Korea

Number of Shares			Value
		> Korea—continued
	578,438	CJ Hellovision	$	6,430,412
		Cable TV, Broadband & Mobile Virtual Network Operator
				231,041,199
		> China 2.8%
	28,645,000	China Everbright International		48,043,333
		Private Municipal Waste Operator
	90,360,000	Sihuan Pharmaceuticals (d)		47,915,014
		Chinese Generic Drug Manufacturer
	850,000	WuXi PharmaTech - ADR (c)		32,963,000
		Contract Research Organization in China
	560,250	BitAuto - ADR (a)(c)		28,505,520
		Automotive Information Website for Buyers & Dealers
	23,671,000	Sino Biopharmaceutical		23,947,553
		Pharmaceutical Developer
	47,500,000	AMVIG Holdings (b)		21,199,203
		Chinese Tobacco Packaging Material Supplier
	32,790,000	NewOcean Energy (a)		16,214,941
		Southern China Liquefied Petroleum Gas Distributor
				218,788,564
		> Hong Kong 2.0%
	52,849,000	Mapletree Greater China Commercial Trust		40,044,589
		Retail & Office Property Landlord
	1,800,000	Melco Crown Entertainment - ADR		38,628,000
		Macau Casino Operator
	15,000,000	Melco International		25,241,556
		Macau Casino Operator
	13,120,000	Lifestyle International		23,387,925
		Mid- to High-end Department Store Operator in Hong Kong & China
	9,347,000	Vitasoy International		14,612,505
		Hong Kong Soy Food Brand
	25,223,000	Sa Sa International (a)		12,331,562
		Cosmetics Retailer
	4,358,000	Kingboard Chemicals		6,896,783
		Paper & Glass Laminates, PCB, Specialty Chemicals & Properties
				161,142,920
		> Indonesia 1.6%
	19,000,000	Matahari Department Store		28,572,485
		Department Store Chain in Indonesia
	33,000,000	Tower Bersama Infrastructure		23,913,958
		Communications Towers
	43,000,000	Link Net (c)		19,650,096
		Fixed Broadband & CATV Service Provider
	324,290,000	Ace Indonesia		18,222,015
		Home Improvement Retailer
	220,150,800	Arwana Citramulia		13,638,405
		Ceramic Tiles for Home Decoration
	6,000,000	Mayora Indah		13,247,935
		Consumer Branded Food Manufacturer

Number of Shares			Value
	54,460,800	MNC Sky Vision	$	6,872,682
		Satellite Pay TV Operator in Indonesia
	11,854,300	Surya Citra Media		3,075,780
		Free to Air TV Station in Indonesia
				127,193,356
		> Philippines 1.2%
	16,000,000	Robinsons Retail Holdings		30,067,114
		Multi-format Retailer in the Philippines
	31,000,000	Puregold Price Club		28,802,453
		Supermarket Operator in the Philippines
	90,000,000	Melco Crown (Philippines) Resorts		18,437,287
		Integrated Resort Operator in Manila
	3,106,980	Universal Robina		15,694,116
		Branded Consumer Food Manufacturer in the Philippines
				93,000,970
		> Thailand 1.1%
	4,360,000	Airports of Thailand		37,468,787
		Airport Operator of Thailand
	107,731,500	Home Product Center		26,982,536
		Home Improvement Retailer
	14,485,000	Robinson Department Store		21,137,451
		Department Store Operator in Thailand
				85,588,774
		> Cambodia 0.5%
	60,000,000	Nagacorp		39,837,465
		Casino & Entertainment Complex in Cambodia
		> Malaysia 0.4%
	43,839,000	7-Eleven Malaysia Holdings		18,939,490
		Exclusive 7-Eleven Franchisor for Malaysia
	17,441,500	Aeon		13,924,175
		Shopping Center & Department Store Operator
	410,300	Astro Malaysia Holdings		353,945
		Largest Pay TV Operator in Malaysia
				33,217,610
Asia: Total				3,659,724,453
Europe 30.3%
		> United Kingdom 9.7%
	1,300,000	Spirax Sarco		65,733,891
		Steam Systems for Manufacturing & Process Industries
	3,300,000	Babcock International		48,139,956
		Public Sector Outsourcer
	2,430,000	WH Smith		46,690,913
		Newsprint, Books & General Stationery Retailer
	1,980,000	Aggreko		44,788,588
		Temporary Power & Temperature Control Services

COLUMBIA ACORN INTERNATIONAL®

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> United Kingdom—continued
	2,630,000	Jardine Lloyd Thompson Group	$	40,847,051
		International Business Insurance Broker
	45,000,000	Cable and Wireless		40,580,484
		Telecommunications Service Provider in the Caribbean
	872,000	Rightmove		38,685,198
		Internet Real Estate Listings
	473,398	Whitbread		36,759,324
		UK Hotelier & Coffee Shop
	39,805,000	Assura		36,756,594
		UK Primary Health Care Property Developer
	4,800,000	Abcam		34,478,114
		Online Sales of Antibodies
	14,379,428	Connect Group (b)		32,902,209
		Newspaper & Magazine Distributor
	958,646	Fidessa Group		31,370,544
		Software for Financial Trading Systems
	2,660,000	Domino's Pizza UK & Ireland		30,584,995
		Pizza Delivery in the UK, Ireland & Germany
	7,430,000	Polypipe		30,361,802
		Manufacturer of Plastic Piping & Fittings
	4,372,390	Halfords		29,768,064
		UK Retailer of Leisure Goods & Auto Parts
	2,725,000	Halma		28,155,791
		Health & Safety Sensor Technology
	4,712,000	Ocado (c)		24,555,590
		Online Grocery Retailer
	5,650,001	Elementis		24,268,770
		Specialty Chemicals
	3,075,000	PureCircle (c)		23,605,530
		Natural Sweeteners
	1,280,000	Smith & Nephew		21,826,005
		Medical Equipment & Supplies
	908,500	AVEVA		19,859,269
		Engineering Software
	5,800,000	RPS Group		19,384,181
		Consultant Specializing in Energy, Water, Urban Planning, Health & Safety
	1,480,000	Shaftesbury		18,204,048
		London Prime Retail REIT
				768,306,911
		> Sweden 3.3%
	1,723,394	Hexagon		61,189,258
		Design, Measurement & Visualization Software & Equipment
	948,422	Unibet		52,034,555
		European Online Gaming Operator
	3,255,024	Sweco		41,767,331
		Engineering Consultants
	1,137,000	Modern Times Group		34,819,232
		Leading Nordic TV Broadcaster

Number of Shares			Value
	1,044,000	Mekonomen	$	27,578,479
		Nordic Integrated Wholesaler/Retailer of Automotive Parts & Service
	856,000	Swedish Match		25,168,699
		Swedish Snus
	979,403	Recipharm		20,868,244
		Contract Development Manufacturing Organization
				263,425,798
		> Germany 3.2%
	608,000	MTU Aero Engines		59,565,285
		Airplane Engine Components & Services
	1,350,000	Wirecard		56,896,015
		Online Payment Processing & Risk Management
	795,000	NORMA Group		39,914,542
		Clamps for Automotive & Industrial Applications
	117,000	Rational		39,108,699
		Commercial Ovens
	795,000	Aurelius		33,200,743
		European Turnaround Investor
	745,000	Elringklinger		22,335,498
		Automobile Components
				251,020,782
		> Spain 2.5%
	10,110,000	Distribuidora Internacional de Alimentación		78,898,061
		Discount Retailer in Spain & Latin America
	671,000	Viscofan		40,997,093
		Sausage Casings Maker
	6,564,000	Prosegur		37,381,026
		Security Guards
	830,000	Bolsas y Mercados Españoles		36,962,561
		Spanish Stock Markets
				194,238,741
		> France 2.5%
	1,350,000	Neopost		74,248,723
		Postage Meter Machines
	1,110,000	Eutelsat		36,820,093
		Fixed Satellite Services
	163,400	Norbert Dentressangle		27,653,030
		European Logistics & Transport Group
	729,096	Saft		26,646,043
		Niche Battery Manufacturer
	90,000	Eurofins Scientific		24,223,322
		Food, Pharmaceuticals & Materials Screening & Testing
	1,831,204	Hi-Media (a)(c)		4,331,806
		Online Advertiser in Europe
				193,923,017
		> Netherlands 2.4%
	2,103,770	Aalberts Industries		66,210,805
		Flow Control & Heat Treatment
	718,124	Vopak		39,631,057
		Operator of Petroleum & Chemical Storage Terminals
	324,700	Gemalto		25,871,571
		Digital Security Solutions

Number of Shares			Value
		> Netherlands—continued
	790,670	Arcadis	$	25,392,286
		Engineering Consultants
	1,201,000	Brunel		22,973,243
		Temporary Specialist & Energy Staffing
	114,395	Core Labs (a)		11,953,133
		Oil & Gas Reservoir Consulting
				192,032,095
		> Switzerland 2.0%
	179,000	Geberit		66,984,611
		Plumbing Supplies
	213,500	Partners Group		63,650,182
		Private Markets Asset Management
	72,500	INFICON		25,906,179
		Gas Detection Instruments
				156,540,972
		> Denmark 1.6%
	1,932,063	SimCorp		63,395,100
		Software for Investment Managers
	1,315,800	Novozymes		60,064,949
		Industrial Enzymes
				123,460,049
		> Finland 1.1%
	7,766,000	Sponda		33,325,704
		Office, Retail & Logistics Properties
	1,669,000	Tikkurila		31,826,484
		Decorative & Industrial Paint in Scandinavia, Central & Eastern Europe
	711,000	Konecranes		22,404,346
		Manufacture & Service of Industrial Cranes & Port Handling Equipment
				87,556,534
		> Norway 0.7%
	2,613,864	Atea		29,446,002
		Nordic IT Hardware/Software Reseller & Integrator
	3,784,000	Orkla		28,559,071
		Food & Brands, Aluminum, Chemicals Conglomerate
				58,005,073
		> Italy 0.6%
	1,909,000	Pirelli		31,599,156
		Global Tire Supplier
	385,950	Industria Macchine Automatiche		18,158,768
		Food & Drugs Packaging & Machinery
				49,757,924
		> Kazakhstan 0.5%
	5,143,000	Halyk Savings Bank of Kazakhstan - GDR		38,006,770
		Retail Bank & Insurer in Kazakhstan
		> Belgium 0.2%
	516,965	EVS Broadcast Equipment		19,241,329
		Digital Live Mobile Production Software & Systems
Europe: Total				2,395,515,995

Number of Shares			Value
Other Countries 16.8%
		> Canada 4.6%
	800,772	CCL Industries	$	90,095,148
		Global Label Converter
	898,000	Vermilion Energy (a)		37,754,925
		Canadian Exploration & Production Company
	3,188,000	CAE		37,202,353
		Flight Simulator Equipment & Training Centers
	1,067,730	ShawCor		29,674,388
		Oil & Gas Pipeline Products
	490,200	Onex Capital		28,466,472
		Private Equity
	2,115,898	Rona		27,063,714
		Canadian Home Improvement Retailer
	363,000	Keyera		24,146,500
		Integrated Supply of Hydrocarbon Processing, Transport & Storage
	1,010,000	Prairie Sky Royalty		23,827,563
		Canadian Owner of Oil & Gas Mineral Interests
	3,360,105	DeeThree Exploration (b)(c)		16,899,348
	1,130,000	DeeThree Exploration (b)(c)(e)		5,569,569
		Canadian Oil & Gas Producer
	531,286	Ag Growth		21,586,181
		Manufacturer of Augers & Grain Handling Equipment
	1,358,857	Baytex		21,489,800
		Oil & Gas Producer in Canada
				363,775,961
		> South Africa 4.4%
	13,683,594	Coronation Fund Managers		110,604,076
		South African Fund Manager
	493,188	Naspers		75,650,609
		Media in Africa, China, Russia & other Emerging Markets
	19,045,300	Rand Merchant Insurance		72,523,066
		Directly Sold Property & Casualty Insurance; Holdings in other Insurers
	2,644,083	Mr. Price		56,551,952
		South African Retailer of Apparel, Household & Sporting Goods
	8,679,940	Northam Platinum (c)		32,809,939
		Platinum Mining in South Africa
				348,139,642
		> Australia 4.0%
	46,578,144	Spotless		80,341,311
		Facility Management & Catering Company
	2,428,257	Domino's Pizza Enterprises		68,488,949
		Domino's Pizza Operator in Australia & New Zealand
	12,550,000	Challenger Financial		68,127,203
		Annuity Provider in Australia
	4,270,000	Amcor		45,496,668
		Global Leader in Flexible & Rigid Packaging
	5,260,000	IAG		24,348,489
		General Insurance Provider

COLUMBIA ACORN INTERNATIONAL®

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Australia—continued
	5,000,000	Estia Health (c)	$	23,344,573
		Residential Aged Care Operator
	1,217,356	Austbrokers		8,025,667
		Local Australian Small Business Insurance Broker
				318,172,860
		> United States 1.8%
	350,000	Cimarex Energy		40,281,500
		Oil & Gas Producer in Texas, New Mexico & Oklahoma
	350,000	Synageva BioPharma (a)(c)		34,135,500
		Biotech Focused on Orphan Diseases
	912,000	Bladex		29,904,480
		Latin American Trade Financing House
	933,297	Textainer Group Holdings		27,989,577
		Top International Container Leasor
	634,500	Hornbeck Offshore (c)		11,934,945
		Supply Vessel Operator in Gulf of Mexico
				144,246,002
		> New Zealand 1.1%
	10,800,000	Auckland International Airport		36,276,163
		Auckland Airport Operator
	8,000,000	Sky City Entertainment		24,485,318
		Casino & Entertainment Complex
	4,011,000	Ryman Healthcare		23,473,337
		Retirement Village Operator
				84,234,818
		> Israel 0.6%
	791,000	Caesarstone		48,021,610
		Quartz Countertops
		> Egypt 0.3%
	3,119,000	Commercial International Bank of Egypt		22,992,074
		Leading Private Universal Bank in Egypt
Other Countries: Total				1,329,582,967
Latin America 2.7%
		> Brazil 1.1%
	3,500,000	Localiza Rent A Car		40,115,305
		Car Rental
	6,487,000	Odontoprev		22,256,474
		Dental Insurance
	1,400,000	Linx		20,423,932
		Retail Management Software in Brazil
	3,421,215	Beadell Resources		668,635
		Gold Mining in Brazil
				83,464,346
		> Mexico 0.7%
	252,000	Grupo Aeroportuario del Sureste - ADR (c)		33,873,840
		Mexican Airport Operator
	12,339,000	Qualitas		22,326,443
		Auto Insurer in Mexico & Central America
				56,200,283

Number of Shares			Value
		> Colombia 0.3%
	23,377,000	Isagen	$	27,423,019
		Colombian Electricity Provider
		> Guatemala 0.2%
	1,626,600	Tahoe Resources		17,825,753
		Silver Project in Guatemala
		> Chile 0.2%
	921,000	Sociedad Quimica y Minera de Chile - ADR		16,808,250
		Producer of Specialty Fertilizers, Lithium & Iodine
		> Uruguay 0.2%
	1,306,818	Union Agriculture Group (c)(d)(e)		14,231,248
		Farmland Operator in Uruguay
Latin America: Total				215,952,899
Total Equities: 96.0% (Cost: $5,887,120,937)				7,600,776,314	(f)
Short-Term Investments 3.0%
	220,000,000	JPMorgan U.S. Government Money Market Fund, IM Shares (7 day yield of 0.01%)		220,000,000
	18,955,990	JPMorgan U.S. Government Money Market Fund, Agency Shares (7 day yield of 0.01%)		18,955,990
Total Short-Term Investments: 3.0% (Cost: $238,955,990)				238,955,990
Securities Lending Collateral 0.8%
	64,494,251	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (g)		64,494,251
Total Securities Lending Collateral: 0.8% (Cost: $64,494,251)				64,494,251
Total Investments: 99.8% (Cost: $6,190,571,178)(h)				7,904,226,555	(i)
Obligation to Return Collateral for Securities Loaned: (0.8)%				(64,494,251	)
Cash and Other Assets Less Liabilities: 1.0%				76,968,177
Net Assets: 100.0%			$	7,916,700,481

ADR - American Depositary Receipts

GDR - Global Depositary Receipts

REIT - Real Estate Investment Trust

> Notes to Statement of Investments

(a) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $61,874,636.

Security	Balance of Shares Held 12/31/14		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 3/31/15		Value		Dividend
Connect Group		14,379,428		—		—		14,379,428	$	32,902,209	$	1,445,996
Tamron		1,402,000		—		—		1,402,000		30,165,507		—
DeeThree Exploration		3,298,377		1,191,728		—		4,490,105		22,468,917		—
AMVIG Holdings		35,119,000		12,381,000		—		47,500,000		21,199,203		1,771,515
Icom		835,000		—		—		835,000		20,067,394		105,159
Total of Affiliated Transactions		55,033,805		13,572,728		—		68,606,533	$	126,803,230	$	3,322,670

The aggregate cost and value of these companies at March 31, 2015, was $135,989,948 and $126,803,230, respectively. Investments in affiliated companies represented 1.60% of the Fund's total net assets at March 31, 2015.

(d) Illiquid security.

(e) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at fair value determined in good faith under consistently applied procedures established by the Fund's Board of Trustees. At March 31, 2015, the market value of these securities amounted to $19,800,817, which represented 0.25% of total net assets. Additional information on these securities is as follows:

Security	Acquisition Dates	Shares/Units		Cost		Value
Union Agriculture Group	12/8/10-6/27/12		1,306,818	$	15,000,000	$	14,231,248
DeeThree Exploration	9/7/10		1,130,000		2,950,812		5,569,569
				$	17,950,812	$	19,800,817

(f) On March 31, 2015, the Fund's total equity investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Japanese Yen	$	1,752,901,750		22.1
Euro		975,817,289		12.3
British Pound		768,306,911		9.7
U.S. Dollar		407,237,374		5.2
Other currencies less than 5% of total net assets		3,696,512,990		46.7
Total Equities	$	7,600,776,314		96.0

(g) Investment made with cash collateral received from securities lending activity.

(h) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $6,190,571,178 and net unrealized appreciation was $1,713,655,377 consisting of gross unrealized appreciation of $2,053,936,632 and gross unrealized depreciation of $340,281,255.

(i) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

COLUMBIA ACORN INTERNATIONAL®

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

amortized cost. Additionally, securities fair valued by the Valuation Committee (the Committee) of the Fund's Board of Trustees (the Board) that rely on significant observable inputs are also included in Level 2. Typical Level 3 securities include any security fair valued by the Committee that relies on significant unobservable inputs.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Asia	$	100,096,520	$	3,511,712,919	$	47,915,014	$	3,659,724,453
Europe		11,953,133		2,383,562,862		-		2,395,515,995
Other Countries		550,474,004		779,108,963		-		1,329,582,967
Latin America		201,053,016		668,635		14,231,248		215,952,899
Total Equities		863,576,673		6,675,053,379		62,146,262		7,600,776,314
Total Short-Term Investments		238,955,990		-		-		238,955,990
Total Securities Lending Collateral		64,494,251		-		-		64,494,251
Total Investments	$	1,167,026,914	$	6,675,053,379	$	62,146,262	$	7,904,226,555

The following table shows transfers between Level 2 and Level 3 of the fair value hierarchy:

Transfers In				Transfers Out
Level 2		Level 3		Level 2		Level 3
$	-	$	55,274,689	$	55,274,689	$	-

There were no transfers of financial assets between levels 1 and 2 during the period. Transfers in and/or out of Level 3 are determined based on the fair value at the beginning of the period for security positions held throughout the period.

The Fund does not hold any significant investments (greater than one percent of net assets) categorized as Level 3.

COLUMBIA ACORN INTERNATIONAL®

PORTFOLIO DIVERSIFICATION (UNAUDITED)

At March 31, 2015, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value		Percentage of Net Assets
> Industrial Goods & Services
Machinery	$	530,793,001		6.7
Industrial Materials & Specialty Chemicals		517,728,665		6.5
Other Industrial Services		440,656,780		5.6
Electrical Components		227,017,895		2.9
Outsourcing Services		188,835,536		2.4
Conglomerates		167,532,689		2.1
Construction		97,346,414		1.2
Waste Management		48,043,333		0.6
Industrial Distribution		12,770,515		0.2
		2,230,724,828		28.2
> Consumer Goods & Services
Retail		664,552,991		8.4
Food & Beverage		291,855,950		3.7
Casinos & Gaming		214,853,543		2.7
Nondurables		179,214,101		2.3
Restaurants		135,833,268		1.7
Other Durable Goods		118,142,373		1.5
Consumer Goods Distribution		107,620,742		1.3
Furniture & Textiles		48,021,610		0.6
Educational Services		40,933,231		0.5
Travel		40,115,304		0.5
Apparel		31,943,755		0.4
Consumer Electronics		30,165,507		0.4
Other Consumer Services		23,387,925		0.3
		1,926,640,300		24.3
> Information
Business Software		228,975,021		2.9
Internet Related		142,841,327		1.8
Financial Processors		122,119,022		1.5
Mobile Communications		116,418,269		1.5
Computer Hardware & Related Equipment		114,747,101		1.4
Semiconductors & Related Equipment		95,259,120		1.2
Entertainment Programming		73,597,561		0.9
Instrumentation		70,661,521		0.9
Advertising		68,287,818		0.9
Computer Services		56,289,302		0.7
Satellite Broadcasting & Services		44,046,720		0.6
Telephone & Data Services		40,580,484		0.5
TV Broadcasting		37,895,011		0.5
Business Information & Marketing Services		29,853,954		0.4
Cable TV		26,080,507		0.3
Telecommunications Equipment		25,188,620		0.3
		1,292,841,358		16.3

	Value			Percentage of Net Assets
> Finance
Insurance	$	258,454,394			3.3
Banks		191,353,858			2.4
Brokerage & Money Management		174,254,258			2.2
Finance Companies		56,456,049			0.7
Financial Processors		36,962,561			0.5
		717,481,120			9.1
> Other Industries
Real Estate		455,418,019			5.8
Transportation		202,031,927			2.6
Regulated Utilities		27,423,019			0.3
		684,872,965			8.7
> Health Care
Pharmaceuticals		185,339,101			2.4
Medical Supplies		90,091,589			1.1
Medical Equipment & Devices		46,918,399			0.6
Health Care Services		46,817,909			0.5
Biotechnology & Drug Delivery		34,135,501			0.5
		403,302,499			5.1
> Energy & Minerals
Oil & Gas Producers		145,822,704			1.9
Mining		63,257,461			0.8
Oil Refining, Marketing & Distribution		79,992,498			1.0
Oil Services		41,609,333			0.5
Agricultural Commodities		14,231,248			0.1
		344,913,244			4.3
Total Equities:		7,600,776,314			96.0
Short-Term Investments:		238,955,990			3.0
Securities Lending Collateral:		64,494,251			0.8
Total Investments:		7,904,226,555			99.8
Obligation to Return Collateral for Securities Loaned:		(64,494,251	)		(0.8	)
Cash and Other Assets Less Liabilities:		76,968,177			1.0
Net Assets:	$	7,916,700,481			100.0

COLUMBIA ACORN USA®

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Information
Amber Road		0		816,768
DemandWare		119,000		145,000
Gogo		0		422,081
Rubicon Technology		50,657		600,000
Solera Holdings		0		196,000
Textura		128,934		373,934
Consumer Goods & Services
Performance Sports Group		0		359,668
The Fresh Market		184,000		234,000
Finance
Marlin Business Services		91,000		418,543
Patriot National		0		515,590
Health Care
Agios Pharmaceuticals		0		26,000
HealthSouth		124,200		154,200
Ultragenyx Pharmaceutical		60,385		154,000
Other Industries
Heartland Express		0		414,000
Energy & Minerals
Carrizo Oil & Gas		120,000		148,000

	Number of Shares
	12/31/14		3/31/15
Sales
Information
Ansys		330,000		230,000
CalAmp		281,000		0
E2Open		196,000		0
Exa		171,861		0
Five9		315,000		0
Informatica		633,000		214,000
IPG Photonics		427,000		383,000
Ixia		369,000		0
Mettler-Toledo International		157,000		141,000
NetSuite		134,000		116,929
Industrial Goods & Services
Acuity Brands		106,000		64,000
ESCO Technologies		320,000		247,000
Generac		317,000		276,000
KAR Auction Services		151,000		0
Middleby		129,000		91,000
Moog		312,000		238,000
Thermon		312,013		260,598
Consumer Goods & Services
Avis Budget Group		791,950		425,950
B&G Foods		65,000		0
Boulder Brands		612,705		0
Buffalo Wild Wings		18,500		0
Caesarstone (Israel)		225,187		189,814
Casey's General Stores		130,279		73,931
Fox Factory Holding		102,184		0
Hertz		469,000		345,000
Interface		502,000		0
Kate Spade & Company		135,000		0
Michaels Stores		368,564		203,784
Shutterfly		185,991		147,845
Finance
Associated Banc-Corp		993,000		930,000
CAI International		673,208		495,208
City National		130,000		0
Enstar Group		33,728		0
McGrath Rentcorp		315,000		227,000
Textainer Group Holdings		83,000		0
Valley National Bancorp		546,750		0
World Acceptance		180,689		135,125

	Number of Shares
	12/31/14		3/31/15
Sales (continued)
Heath Care
Akorn		657,117		442,117
Allscripts Healthcare Solutions		581,600		343,600
BioMarin Pharmaceutical		33,600		0
Celldex Therapeutics		349,300		280,300
Cepheid		558,500		494,500
NPS Pharmaceuticals		177,200		0
Seattle Genetics		380,800		286,800
Synageva BioPharma		317,200		271,469
Other Industries
DCT Industrial Trust		217,750		0
Extra Space Storage		832,000		611,000
St. Joe		153,098		0
Energy & Minerals
Bonanza Creek Energy		47,000		0
Chart Industries		84,000		0
Core Labs (Netherlands)		55,000		39,000
Hornbeck Offshore		198,000		137,000
US Silica		49,000		0
WPX Energy		129,000		0

COLUMBIA ACORN USA®

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 94.3%
Information 23.8%
		> Business Software 8.0%
	230,000	Ansys (a)	$	20,283,700
		Simulation Software for Engineers & Designers
	249,424	SPS Commerce (a)		16,736,351
		Supply Chain Management Software Delivered via the Web
	116,929	NetSuite (a)		10,846,334
		End-to-end IT Systems Solution Delivered via the Web
	373,934	Textura (a)		10,163,526
		Construction Vendor Management Software
	196,000	Solera Holdings		10,125,360
		Software for Automotive Insurance Claims Processing
	214,000	Informatica (a)		9,384,970
		Enterprise Data Integration Software
	145,000	DemandWare (a)		8,830,500
		E-Commerce Website Platform for Retailers & Apparel Manufacturers
	816,768	Amber Road (a)		7,555,104
		Global Trade Management Software Delivered via the Web
	82,000	Envestnet (a)		4,598,560
		Technology Platform for Investment Advisors
	97,000	Fleetmatics (a)		4,350,450
		Fleet Management Software
	394,187	inContact (a)		4,296,638
		Call Center Systems Delivered via the Web & Telco Services
				107,171,493
		> Instrumentation 6.6%
	141,000	Mettler-Toledo International (a)		46,339,650
		Laboratory Equipment
	383,000	IPG Photonics (a)		35,504,100
		Fiber Lasers
	274,000	Trimble Navigation (a)		6,904,800
		GPS-based Instruments
				88,748,550
		> Computer Services 3.1%
	506,000	ExlService Holdings (a)		18,823,200
		Business Process Outsourcing
	227,000	Virtusa (a)		9,393,260
		Offshore IT Outsourcing
	327,000	WNS - ADR (a)		7,952,640
		Offshore Business Process Outsourcing Services
	432,000	Hackett Group		3,862,080
		IT Integration & Best Practice Research
	302,000	RCM Technologies		2,023,400
		Technology & Engineering Services
				42,054,580

Number of Shares			Value
		> Semiconductors & Related Equipment 1.4%
	152,000	Monolithic Power Systems	$	8,002,800
		High Performance Analog & Mixed Signal Integrated Circuits
	970,000	Atmel		7,983,100
		Microcontrollers, Radio Frequency & Memory Semiconductors
	600,000	Rubicon Technology (a)(b)		2,364,000
		Producer of Sapphire for the Lighting, Electronics & Automotive Industries
				18,349,900
		> Computer Hardware & Related Equipment 1.2%
	101,000	Rogers (a)		8,303,210
		Printed Circuit Materials & High Performance Foams
	78,000	Belden		7,297,680
		Specialty Cable
				15,600,890
		> Mobile Communications 0.8%
	422,081	Gogo (a)(b)		8,044,864
		Provider of Wi-Fi on Airplanes
	23,000	SBA Communications (a)		2,693,300
		Communications Towers
				10,738,164
		> Internet Related 0.7%
	280,831	RetailMeNot (a)(b)		5,057,766
		Digital Coupon Marketplace
	951,000	Vonage (a)		4,669,410
		Business & Consumer Internet Telephony
				9,727,176
		> Telecommunications Equipment 0.7%
	484,278	Infinera (a)		9,525,748
		Optical Networking Equipment
		> Financial Processors 0.6%
	77,000	Global Payments		7,059,360
		Credit Card Processor
	153,000	Liquidity Services (a)		1,511,640
		E-Auctions for Surplus & Salvage Goods
				8,571,000
		> Business Information & Marketing Services 0.4%
	211,000	RPX (a)		3,036,290
		Patent Aggregation & Defensive Patent Consulting
	218,000	Bankrate (a)		2,472,120
		Internet Advertising for the Insurance, Credit Card & Banking Markets
				5,508,410
		> Telephone & Data Services 0.3%
	621,000	Boingo Wireless (a)		4,682,340
		Wi-Fi & Cellular Communications Networks
Information: Total				320,678,251

Number of Shares			Value
Industrial Goods & Services 21.9%
		> Machinery 17.3%
	793,000	Ametek	$	41,664,220
		Aerospace/Industrial Instruments
	515,000	Nordson		40,345,100
		Dispensing Systems for Adhesives & Coatings
	725,500	HEICO		35,941,270
		FAA-approved Aircraft Replacement Parts
	855,000	Donaldson		32,242,050
		Industrial Air Filtration
	238,000	Moog (a)		17,861,900
		Motion Control Products for Aerospace, Defense & Industrial Markets
	222,000	Toro		15,566,640
		Turf Maintenance Equipment
	276,000	Generac (a)		13,438,440
		Standby Power Generators
	247,000	ESCO Technologies		9,628,060
		Industrial Filtration & Advanced Measurement Equipment
	91,000	Middleby (a)		9,341,150
		Manufacturer of Cooking Equipment
	239,000	Kennametal		8,051,910
		Consumable Cutting Tools
	149,293	Dorman Products (a)(b)		7,427,327
		Aftermarket Auto Parts Distributor
	64,000	Graham		1,534,080
		Designer & Builder of Vacuum & Heat Transfer Equipment for Process Industries
				233,042,147
		> Industrial Materials & Specialty Chemicals 2.4%
	539,000	Drew Industries		33,170,060
		RV & Manufactured Home Components
		> Electrical Components 1.3%
	64,000	Acuity Brands		10,762,240
		Commercial Lighting Fixtures
	260,598	Thermon (a)		6,272,594
		Global Engineered Thermal Solutions
				17,034,834
		> Industrial Distribution 0.5%
	90,000	WESCO International (a)		6,290,100
		Industrial Distributor
		> Construction 0.4%
	449,000	PGT (a)		5,017,575
		Wind Resistant Windows & Doors
Industrial Goods & Services: Total				294,554,716
Consumer Goods & Services 14.8%
		> Travel 3.7%
	425,950	Avis Budget Group (a)		25,137,439
		Car Rental Company
	281,000	HomeAway (a)		8,477,770
		Vacation Rental Online Marketplace

Number of Shares			Value
	345,000	Hertz (a)	$	7,479,600
		U.S. Rental Car Operator
	89,666	Choice Hotels		5,744,901
		Franchisor of Budget Hotel Brands
	29,000	Vail Resorts		2,999,180
		Ski Resort Operator & Developer
				49,838,890
		> Retail 3.0%
	207,500	Burlington Stores (a)		12,329,650
		Off-price Apparel Retailer
	234,000	The Fresh Market (a)		9,509,760
		Specialty Food Retailer
	147,845	Shutterfly (a)		6,688,508
		Internet Photo-centric Retailer
	73,931	Casey's General Stores		6,661,183
		Owner/Operator of Convenience Stores
	203,784	Michaels Stores (a)		5,514,395
		Craft & Hobby Specialty Retailer
				40,703,496
		> Consumer Goods Distribution 2.5%
	260,000	Pool		18,137,600
		Swimming Pool Supplies & Equipment Distributor
	134,000	United Natural Foods (a)		10,323,360
		Distributor of Natural/Organic Foods to Grocery Stores
	268,276	The Chefs' Warehouse (a)		6,017,431
		Distributor of Specialty Foods to Fine Dining Restaurants
				34,478,391
		> Other Durable Goods 2.2%
	187,000	Cavco Industries (a)		14,036,220
		Manufactured Homes
	297,000	Select Comfort (a)		10,237,590
		Specialty Mattresses
	296,000	Gentex		5,416,800
		Manufacturer of Auto Parts
				29,690,610
		> Furniture & Textiles 1.5%
	189,814	Caesarstone (Israel)		11,523,608
		Quartz Countertops
	357,000	Knoll		8,364,510
		Office Furniture
				19,888,118
		> Restaurants 0.7%
	79,000	Papa John's International		4,882,990
		Franchisor of Pizza Restaurants
	68,000	Fiesta Restaurant Group (a)		4,148,000
		Owner/Operator of Two Restaurant Chains: Pollo Tropical & Taco Cabana
				9,030,990
		> Other Consumer Services 0.7%
	252,000	Blackhawk Network (a)		8,958,600
		Third-party Distributor of Prepaid Content, Mostly Gift Cards

COLUMBIA ACORN USA®

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Leisure Products 0.5%
	359,668	Performance Sports Group (a)	$	7,013,526
		Sporting Goods Manufacturer
Consumer Goods & Services: Total				199,602,621
Finance 12.7%
		> Banks 7.9%
	733,000	MB Financial		22,950,230
		Chicago Bank
	140,000	SVB Financial Group (a)		17,785,600
		Bank to Venture Capitalists
	930,000	Associated Banc-Corp		17,298,000
		Midwest Bank
	392,597	Lakeland Financial		15,931,586
		Indiana Bank
	1,484,641	First Busey		9,932,249
		Illinois Bank
	228,000	Hancock Holding		6,808,080
		Gulf Coast Bank
	695,000	TrustCo Bank		4,781,600
		New York State Bank
	172,101	Sandy Spring Bancorp		4,514,209
		Baltimore & Washington, D.C. Bank
	379,000	First Commonwealth		3,411,000
		Western Pennsylvania Bank
	154,849	Guaranty Bancorp		2,626,239
		Colorado Bank
				106,038,793
		> Finance Companies 2.8%
	495,208	CAI International (a)		12,167,261
		International Container Leasing
	135,125	World Acceptance (a)(b)		9,853,315
		Personal Loans
	418,543	Marlin Business Services		8,383,416
		Small Equipment Leasing
	227,000	McGrath Rentcorp		7,470,570
		Mini-rental Conglomerate
				37,874,562
		> Insurance 0.9%
	515,590	Patriot National (a)		6,547,993
		Underwriting, Claims Administration & Case Management Outsourcing for Workers Comp Insurers
	135,000	Allied World Assurance Company Holdings		5,454,000
		Commercial Lines Insurance/Reinsurance
				12,001,993
		> Savings & Loans 0.6%
	373,487	LegacyTexas		8,489,359
		Texas Thrift
		> Brokerage & Money Management 0.5%
	139,000	SEI Investments		6,128,510
		Mutual Fund Administration & Investment Management
Finance: Total				170,533,217

Number of Shares			Value
Health Care 12.5%
		> Biotechnology & Drug Delivery 5.2%
	271,469	Synageva BioPharma (a)(b)	$	26,476,371
		Biotech Focused on Orphan Diseases
	286,800	Seattle Genetics (a)		10,138,380
		Antibody-based Therapies for Cancer
	154,000	Ultragenyx Pharmaceutical (a)		9,561,860
		Biotech Focused on "Ultra-Orphan" Drugs
	280,300	Celldex Therapeutics (a)		7,811,961
		Biotech Developing Drugs for Cancer
	17,800	Intercept Pharmaceuticals (a)(b)		5,019,956
		Biotech Developing Drugs for Several Diseases
	338,500	Sarepta Therapeutics (a)(b)		4,495,280
		Biotech Focused on Rare Diseases
	40,100	Alnylam Pharmaceuticals (a)		4,187,242
		Biotech Developing Drugs Primarily for Rare Diseases
	26,000	Agios Pharmaceuticals (a)(b)		2,451,800
		Biotech Focused on Cancer & Orphan Diseases
				70,142,850
		> Medical Supplies 3.3%
	494,500	Cepheid (a)		28,137,050
		Molecular Diagnostics
	135,200	Bio-Techne		13,559,208
		Maker of Consumables & Systems for the Life Science Market
	86,300	VWR (a)		2,242,937
		Distributor of Lab Supplies
				43,939,195
		> Health Care Services 1.8%
	184,500	Medidata Solutions (a)		9,047,880
		Cloud-based Software for Drug Studies
	154,200	HealthSouth		6,840,312
		Inpatient Rehabilitation Facilities & Home Health Care
	110,500	Envision Healthcare Holdings (a)		4,237,675
		Provider of Health Care Outsourcing Services
	343,600	Allscripts Healthcare Solutions (a)		4,109,456
		Health Care IT
	46,268	Castlight Health (a)		359,040
		Provider of Cloud-based Software for Managing Health Care Costs
				24,594,363
		> Pharmaceuticals 1.5%
	442,117	Akorn (a)		21,004,979
		Developer, Manufacturer & Distributor of Specialty Generic Drugs
		> Medical Equipment & Devices 0.7%
	200,300	Wright Medical Group (a)		5,167,740
		Foot & Ankle Replacement

Number of Shares			Value
		> Medical Equipment & Devices—continued
	61,200	Abaxis	$	3,923,532
		Instruments & Tests for Vet & Medical Markets
				9,091,272
Health Care: Total				168,772,659
Other Industries 6.2%
		> Real Estate 4.3%
	611,000	Extra Space Storage		41,285,270
		Self Storage Facilities
	328,933	EdR		11,637,649
		Student Housing
	91,000	Post Properties		5,180,630
		Multifamily Properties
				58,103,549
		> Transportation 1.9%
	468,091	Rush Enterprises, Class A (a)		12,806,970
	105,000	Rush Enterprises, Class B (a)		2,595,600
		Truck Sales & Service
	414,000	Heartland Express		9,836,640
		Regional Trucker
				25,239,210
Other Industries: Total				83,342,759
Energy & Minerals 2.4%
		> Oil & Gas Producers 1.7%
	148,000	Carrizo Oil & Gas (a)		7,348,200
		Oil & Gas Producer
	89,000	SM Energy		4,599,520
		Oil & Gas Producer
	83,000	PDC Energy (a)		4,485,320
		Oil & Gas Producer in the United States
	77,000	Clayton Williams (a)		3,898,510
		Oil & Gas Producer
	159,000	Rosetta Resources (a)		2,706,180
		Oil & Gas Producer Exploring in Texas
				23,037,730
		> Oil Services 0.4%
	137,000	Hornbeck Offshore (a)		2,576,970
		Supply Vessel Operator in Gulf of Mexico

Number of Shares			Value
	51,000	Gulfport Energy (a)	$	2,341,410
		Oil & Gas Producer Focused on Utica Shale in Ohio
				4,918,380
		> Mining 0.3%
	39,000	Core Labs (Netherlands) (b)		4,075,110
		Oil & Gas Reservoir Consulting
Energy & Minerals: Total				32,031,220
Total Equities: 94.3% (Cost: $655,552,202)				1,269,515,443	(c)
Short-Term Investments 4.7%
	64,164,090	JPMorgan U.S. Government Money Market Fund, Agency Shares (7 day yield of 0.01%)		64,164,090
Total Short-Term Investments: 4.7% (Cost: $64,164,090)				64,164,090
Securities Lending Collateral 2.6%
	34,441,850	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (d)		34,441,850
Total Securities Lending Collateral: 2.6% (Cost: $34,441,850)				34,441,850
Total Investments: 101.6% (Cost: $754,158,142)(e)				1,368,121,383	(f)
Obligation to Return Collateral for Securities Loaned: (2.6)%				(34,441,850	)
Cash and Other Assets Less Liabilities: 1.0%				12,248,583
Net Assets: 100.0%			$	1,345,928,116

ADR - American Depositary Receipts

> Notes to Statement of Investments

(a) Non-income producing security.

(b) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $33,038,748.

(c) On March 31, 2015, the market value of foreign securities represented 1.16% of total net assets. The Fund's foreign portfolio was diversified as follows:

Country	Value		Percentage of Net Assets
Israel	$	11,523,608		0.86
Netherlands		4,075,110		0.30
Total Foreign Portfolio	$	15,598,718		1.16

(d) Investment made with cash collateral received from securities lending activity.

COLUMBIA ACORN USA®

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

(e) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $754,158,142 and net unrealized appreciation was $613,963,241 consisting of gross unrealized appreciation of $641,020,566 and gross unrealized depreciation of $27,057,325.

(f) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Information	$	320,678,251	$	-	$	-	$	320,678,251
Industrial Goods & Services		294,554,716		-		-		294,554,716
Consumer Goods & Services		199,602,621		-		-		199,602,621
Finance		170,533,217		-		-		170,533,217
Health Care		168,772,659		-		-		168,772,659
Other Industries		83,342,759		-		-		83,342,759
Energy & Minerals		32,031,220		-		-		32,031,220
Total Equities		1,269,515,443		-		-		1,269,515,443
Total Short-Term Investments		64,164,090		-		-		64,164,090
Total Securities Lending Collateral		34,441,850		-		-		34,441,850
Total Investments	$	1,368,121,383	$	-	$	-	$	1,368,121,383

There were no transfers of financial assets between levels during the period.

COLUMBIA ACORN INTERNATIONAL SELECT^SM

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Asia
> Japan
Aeon Mall		0		133,000
KDDI		360,000		399,000
Recruit Holdings		222,500		297,400
Secom		108,000		132,000
> Singapore
CapitaMall Trust		0		6,491,000
> Korea
KT&G		34,400		68,400
Europe
> United Kingdom
Aggreko		0		97,000
WH Smith		0		126,000
> Germany
MTU Aero Engines		0		56,000
> Switzerland
Geberit		0		7,300
> Spain
Distribuidora Internacional de Alimentación		0		655,000
> France
Eutelsat		105,081		145,081
> Netherlands
Vopak		0		44,000
Other Countries
> Canada
Vermilion Energy		0		56,000
> South Africa
Coronation Fund Managers		390,000		569,000

	Number of Shares
	12/31/14		3/31/15
Sales
Asia
> Japan
NGK Spark Plug		264,000		206,300
Park24		212,000		181,000
> Singapore
Ascendas REIT		7,916,000		2,650,000
Europe
> United Kingdom
Babcock International		556,000		330,000
Jardine Lloyd Thompson Group		290,000		155,000
Smith & Nephew		151,000		140,000
> Switzerland
Partners Group		26,680		21,040
> Spain
Viscofan		66,000		44,000
> Sweden
Hexagon		97,000		62,900
Swedish Match		248,000		120,000
> Denmark
Jyske Bank		67,300		0
Other Countries
> Australia
Amcor		470,000		350,000
IAG		1,300,000		514,000
> Canada
Baytex		370,000		0
CCL Industries		78,000		67,000
Goldcorp		295,000		258,000
> South Africa
Naspers		42,000		33,000

COLUMBIA ACORN INTERNATIONAL SELECT^SM

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 95.0%
Asia 43.5%
		> Japan 25.2%
	297,400	Recruit Holdings	$	9,279,314
		Recruitment & Media Services
	399,000	KDDI		9,014,420
		Mobile & Fixed Line Communication Service Provider in Japan
	132,000	Secom		8,804,444
		Security Services
	190,000	Japan Tobacco		6,006,824
		Cigarettes
	206,300	NGK Spark Plug		5,537,919
		Automobile Parts
	777,000	Seven Bank		3,831,182
		ATM Processing Services
	181,000	Park24		3,703,214
		Parking Lot Operator
	2,560	Orix JREIT		3,666,566
		Diversified REIT
	1,600	Nippon Prologis REIT		3,522,192
		Logistics REIT in Japan
	133,000	Aeon Mall		2,633,814
		Suburban Shopping Mall Developer, Owner & Operator
	1,300	Japan Retail Fund		2,583,207
		Largest Retail REIT in Japan
	32,200	Rinnai		2,386,372
		Gas Appliances for Home & Commercial Use
				60,969,468
		> Singapore 11.3%
	2,036,000	Singapore Exchange		12,072,185
		Singapore Equity & Derivatives Market Operator
	6,491,000	CapitaMall Trust		10,391,560
		Singapore Commercial Property Real Estate Investment Trust
	2,650,000	Ascendas REIT		4,998,516
		Industrial Property Landlord
				27,462,261
		> Korea 7.0%
	37,194	CJ Corp		5,893,642
		Holding Company of Korean Consumer Conglomerate
	23,200	Samsung Fire and Marine		5,593,763
		Non-life Insurance
	68,400	KT&G		5,468,547
		Tobacco & Ginseng Products
				16,955,952
Asia: Total				105,387,681

Number of Shares			Value
Europe 29.8%
		> United Kingdom 7.4%
	330,000	Babcock International	$	4,813,996
		Public Sector Outsourcer
	47,689	Whitbread		3,703,048
		UK Hotelier & Coffee Shop
	126,000	WH Smith		2,421,010
		Newsprint, Books & General Stationery Retailer
	155,000	Jardine Lloyd Thompson Group		2,407,336
		International Business Insurance Broker
	140,000	Smith & Nephew		2,387,219
		Medical Equipment & Supplies
	97,000	Aggreko		2,194,188
		Temporary Power & Temperature Control Services
				17,926,797
		> Germany 7.3%
	1,305,500	Telefonica Deutschland		7,507,185
		Mobile & Fixed-line Communications in Germany
	56,000	MTU Aero Engines		5,486,277
		Airplane Engine Components & Services
	107,400	Wirecard		4,526,394
		Online Payment Processing & Risk Management
				17,519,856
		> Switzerland 3.7%
	21,040	Partners Group		6,272,599
		Private Markets Asset Management
	7,300	Geberit		2,731,774
		Plumbing Supplies
				9,004,373
		> Spain 3.2%
	655,000	Distribuidora Internacional de Alimentación		5,111,596
		Discount Retailer in Spain & Latin America
	44,000	Viscofan		2,688,334
		Sausage Casings Maker
				7,799,930
		> Sweden 2.4%
	120,000	Swedish Match		3,528,322
		Swedish Snus
	62,900	Hexagon		2,233,270
		Design, Measurement & Visualization Software & Equipment
				5,761,592
		> France 2.0%
	145,081	Eutelsat		4,812,519
		Fixed Satellite Services
		> Norway 1.6%
	511,000	Orkla		3,856,682
		Food & Brands, Aluminum, Chemicals Conglomerate

Number of Shares			Value
		> Denmark 1.2%
	65,500	Novozymes	$	2,990,009
		Industrial Enzymes
		> Netherlands 1.0%
	44,000	Vopak		2,428,225
		Operator of Petroleum & Chemical Storage Terminals
Europe: Total				72,099,983
Other Countries 17.2%
		> Australia 7.2%
	2,062,000	Challenger Financial		11,193,490
		Annuity Provider in Australia
	350,000	Amcor		3,729,235
		Global Leader in Flexible & Rigid Packaging
	514,000	IAG		2,379,301
		General Insurance Provider
				17,302,026
		> Canada 6.0%
	67,000	CCL Industries		7,538,194
		Global Label Converter
	258,000	Goldcorp		4,674,960
		Gold Mining
	56,000	Vermilion Energy (a)		2,354,428
		Canadian Exploration & Production Company
				14,567,582
		> South Africa 4.0%
	33,000	Naspers		5,061,903
		Media in Africa, China, Russia & other Emerging Markets
	569,000	Coronation Fund Managers		4,599,210
		South African Fund Manager
				9,661,113
Other Countries: Total				41,530,721

Number of Shares			Value
Latin America 4.5%
		> Guatemala 2.7%
	588,000	Tahoe Resources	$	6,443,835
		Silver Project in Guatemala
		> Brazil 1.0%
	12,057,582	Beadell Resources		2,356,508
		Gold Mining in Brazil
		> Uruguay 0.8%
	191,666	Union Agriculture Group (b)(c)(d)		2,087,243
		Farmland Operator in Uruguay
Latin America: Total				10,887,586
Total Equities: 95.0% (Cost: $202,446,123)				229,905,971	(e)
Securities Lending Collateral 0.5%
	1,257,745	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (f)		1,257,745
Total Securities Lending Collateral: 0.5% (Cost: $1,257,745)				1,257,745
Total Investments: 95.5% (Cost: $203,703,868)(g)				231,163,716	(h)
Obligation to Return Collateral for Securities Loaned: (0.5)%				(1,257,745	)
Cash and Other Assets Less Liabilities: 5.0%				12,053,755
Net Assets: 100.0%			$	241,959,726

REIT - Real Estate Investment Trust

> Notes to Statement of Investments

(a) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $1,197,778.

(b) Non-income producing security.

(d) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. This security is valued at fair value determined in good faith under consistently applied procedures established by the Fund's Board of Trustees. At March 31, 2015, the market value of this security amounted to $2,087,243, which represented 0.86% of total net assets. Additional information on this security is as follows:

Security				Acquisition Dates				Shares/Units				Cost				Value
Union Agriculture Group				12/8/10-6/27/12					191,666			$	2,200,000			$	2,087,243

COLUMBIA ACORN INTERNATIONAL SELECT^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

(e) On March 31, 2015, the Fund's total equity investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Japanese Yen	$	60,969,468		25.2
Euro		32,560,529		13.5
Singapore Dollar		27,462,261		11.3
Australian Dollar		19,658,534		8.1
British Pound		17,926,797		7.4
South Korean Won		16,955,952		7.0
Canadian Dollar		16,336,457		6.8
Other currencies less than 5% of total net assets		38,035,973		15.7
Total Equities	$	229,905,971		95.0

(f) Investment made with cash collateral received from securities lending activity.

(g) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $203,703,868 and net unrealized appreciation was $27,459,848 consisting of gross unrealized appreciation of $43,885,109 and gross unrealized depreciation of $16,425,261.

(h) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

At March 31, 2015, the Fund had entered into the following forward foreign currency exchange contract:

Forward Foreign Currency Exchange Contracts to Buy				Forward Foreign Currency Exchange Contracts to Sell				Principal Amount in Foreign Currency				Principal Amount in U.S. Dollar				Settlement Date				Unrealized Appreciation (Depreciation)
USD				ZAR					110,534,400			$	9,000,000			4/15/15				$	(92,633	)

The counterparty for all forward foreign currency exchange contracts is Morgan Stanley.

USD - U.S. Dollar

ZAR - South African Rand

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

For investments and derivatives categorized as Level 3, the significant unobservable inputs used in the fair value measurement of the Funds' securities may include: (i) data specific to the issuer or comparable issuers, (ii) general market or specific sector news and (iii) quoted prices and specific or similar security transactions. The Committee considers this data and any changes from prior periods in order to assess the reasonableness of observable and unobservable inputs, any assumptions or internal models

> Notes to Statement of Investments

used to value those securities and changes in fair value. Significant changes in any of these factors could result in lower or higher fair value measurements. Various factors impact the frequency of monitoring (which may occur as often as daily), however the Committee may determine that changes to inputs, assumptions and models are not required with the same frequency.

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)			Significant Unobservable Inputs (Level 3)		Total
Equities
Asia	$	-	$	105,387,681		$	-	$	105,387,681
Europe		-		72,099,983			-		72,099,983
Other Countries		14,567,582		26,963,139			-		41,530,721
Latin America		6,443,835		2,356,508			2,087,243		10,887,586
Total Equities		21,011,417		206,807,311			2,087,243		229,905,971
Total Securities Lending Collateral		1,257,745		-			-		1,257,745
Total Investments	$	22,269,162	$	206,807,311		$	2,087,243	$	231,163,716
Unrealized Depreciation on:
Forward Foreign Currency Exchange Contracts		-		(92,633	)		-		(92,633	)
Total	$	22,269,162	$	206,714,678		$	2,087,243	$	231,071,083

The Fund's assets assigned to the Level 2 input category are generally valued using a market approach, in which a security's value is determined through its correlation to prices and information from observable market transactions for similar or identical assets. Foreign equities are generally valued at the last sale price on the foreign exchange or market on which they trade. The Fund may use a statistical fair valuation model, in accordance with the policy adopted by the Board, provided by an independent third party to value securities principally traded in foreign markets in order to adjust for possible stale pricing that may occur between the close of the foreign exchanges and the time for valuation. These models take into account available market data including intraday index, ADR, and ETF movements. Forward foreign currency exchange contracts are valued at the prevailing forward exchange rate of the underlying currencies.

There were no transfers of financial assets between levels during the period.

The Fund does not hold any significant investments (greater than one percent of net assets) categorized as Level 3.

COLUMBIA ACORN INTERNATIONAL SELECT^SM

PORTFOLIO DIVERSIFICATION (UNAUDITED)

At March 31, 2015, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value		Percentage of Net Assets
> Information
Financial Processors	$	16,598,580		6.9
Advertising		9,279,314		3.8
Mobile Communications		9,014,420		3.7
Telephone & Data Services		7,507,185		3.1
Internet Related		5,061,903		2.1
Satellite Broadcasting & Services		4,812,519		2.0
Business Software		2,233,270		0.9
		54,507,191		22.5
> Consumer Goods & Services
Nondurables		19,013,566		7.8
Other Durable Goods		7,924,291		3.3
Retail		7,532,606		3.1
Food & Beverage		6,216,656		2.6
Restaurants		3,703,048		1.5
		44,390,167		18.3
> Industrial Goods & Services
Other Industrial Services		20,188,122		8.4
Conglomerates		9,750,325		4.0
Industrial Materials & Specialty Chemicals		6,719,244		2.8
Outsourcing Services		4,813,996		2.0
Construction		2,731,775		1.1
		44,203,462		18.3
> Finance
Insurance		21,573,889		8.9
Brokerage & Money Management		10,871,808		4.5
Banks		3,831,182		1.6
		36,276,879		15.0
> Other Industries
Real Estate		27,795,854		11.5
		27,795,854		11.5
> Energy & Minerals
Mining		13,475,304		5.6
Oil Refining, Marketing & Distribution		2,428,225		1.0
Oil & Gas Producers		2,354,427		1.0
Agricultural Commodities		2,087,243		0.8
		20,345,199		8.4

	Value			Percentage of Net Assets
> Health Care
Medical Equipment & Devices	$	2,387,219			1.0
		2,387,219			1.0
Total Equities:		229,905,971			95.0
Securities Lending Collateral:		1,257,745			0.5
Total Investments:		231,163,716			95.5
Obligation to Return Collateral for Securities Loaned:		(1,257,745	)		(0.5	)
Cash and Other Assets Less Liabilities:		12,053,755			5.0
Net Assets:	$	241,959,726			100.0

COLUMBIA ACORN SELECT^SM

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Industrial Goods & Services
LKQ		780,000		1,050,000
Information
Bankrate		0		595,000
Solera Holdings		0		390,000
Finance
Associated Banc-Corp		635,000		915,000
Eaton Vance		0		348,000
Consumer Goods & Services
Fossil		0		120,000
Health Care
Ultragenyx Pharmaceutical		0		91,000
Energy & Minerals
Carrizo Oil & Gas		0		106,000
Cimarex Energy		0		45,000
Core Labs (Netherlands)		27,000		47,000
Gulfport Energy		0		109,000

	Number of Shares
	12/31/14		3/31/15
Sales
Industrial Goods & Services
Ametek		779,000		754,000
Kennametal		280,000		260,000
Pall		177,000		163,000
Information
Ansys		190,000		163,000
Informatica		241,000		147,000
Mettler-Toledo International		84,500		59,500
SBA Communications		83,000		60,000
WNS—ADR		1,245,493		875,000
Finance
City National		200,000		0
CNO Financial Group		1,270,000		960,000
Discover Financial Services		319,000		0
Consumer Goods & Services
Casey's General Stores		86,875		0
Hertz		138,000		0
PVH		83,000		0
ULTA		109,000		0
Vail Resorts		210,000		157,080
Heath Care
Cepheid		322,500		243,000
Intercept Pharmaceuticals		18,000		0
Energy & Minerals
Canacol (Colombia)		1,654,000		0
Rowan		173,000		0
ShaMaran Petroleum (Iraq)		20,290,500		0
Other Industries
EdR		341,666		275,000
Extra Space Storage		230,000		166,000
Post Properties		355,000		197,000

COLUMBIA ACORN SELECT^SM

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 97.7%
Industrial Goods & Services 27.7%
		> Machinery 18.3%
	754,000	Ametek	$	39,615,160
		Aerospace/Industrial Instruments
	764,000	Donaldson		28,810,440
		Industrial Air Filtration
	264,000	Nordson		20,681,760
		Dispensing Systems for Adhesives & Coatings
	163,000	Pall		16,363,570
		Life Science, Water & Industrial Filtration
	260,000	Kennametal		8,759,400
		Consumable Cutting Tools
				114,230,330
		> Other Industrial Services 4.3%
	1,050,000	LKQ (a)		26,838,000
		Alternative Auto Parts Distribution
		> Industrial Distribution 2.8%
	167,000	Airgas		17,720,370
		Industrial Gas Distributor
		> Outsourcing Services 2.3%
	500,000	Quanta Services (a)		14,265,000
		Electrical Transmission & Pipeline Contracting Services
Industrial Goods & Services: Total				173,053,700
Information 27.5%
		> Business Software 6.6%
	390,000	Solera Holdings		20,147,400
		Software for Automotive Insurance Claims Processing
	163,000	Ansys (a)		14,374,970
		Simulation Software for Engineers & Designers
	147,000	Informatica (a)		6,446,685
		Enterprise Data Integration Software
				40,969,055
		> Instrumentation 5.3%
	59,500	Mettler-Toledo International (a)		19,554,675
		Laboratory Equipment
	525,000	Trimble Navigation (a)		13,230,000
		GPS-based Instruments
				32,784,675
		> Computer Hardware & Related Equipment 4.7%
	495,000	Amphenol		29,170,350
		Electronic Connectors
		> Computer Services 3.4%
	875,000	WNS - ADR (a)		21,280,000
		Offshore Business Process Outsourcing Services
		> Telecommunications Equipment 3.3%
	181,000	F5 Networks (a)		20,804,140
		Internet Traffic Management Equipment

Number of Shares			Value
		> Internet Related 1.3%
	1,635,000	Vonage (a)	$	8,027,850
		Business & Consumer Internet Telephony
		> Mobile Communications 1.1%
	60,000	SBA Communications (a)		7,026,000
		Communications Towers
		> Business Information & Marketing Services 1.1%
	595,000	Bankrate (a)		6,747,300
		Internet Advertising for the Insurance, Credit Card & Banking Markets
		> Semiconductors & Related Equipment 0.7%
	535,000	Atmel		4,403,050
		Microcontrollers, Radio Frequency & Memory Semiconductors
Information: Total				171,212,420
Finance 12.0%
		> Brokerage & Money Management 6.6%
	610,000	SEI Investments		26,894,900
		Mutual Fund Administration & Investment Management
	348,000	Eaton Vance		14,490,720
		Specialty Mutual Funds
				41,385,620
		> Banks 2.7%
	915,000	Associated Banc-Corp		17,019,000
		Midwest Bank
		> Insurance 2.7%
	960,000	CNO Financial Group		16,531,200
		Life, Long-term Care & Medical Supplement Insurance
Finance: Total				74,935,820
Consumer Goods & Services 10.5%
		> Retail 4.5%
	444,578	The Fresh Market (a)		18,067,650
		Specialty Food Retailer
	120,000	Fossil (a)		9,894,000
		Watch Designer & Retailer
				27,961,650
		> Travel 2.6%
	157,080	Vail Resorts		16,245,213
		Ski Resort Operator & Developer
		> Other Consumer Services 1.7%
	294,000	Blackhawk Network (a)		10,451,700
		Third-party Distributor of Prepaid Content, Mostly Gift Cards
		> Consumer Goods Distribution 1.6%
	134,000	United Natural Foods (a)		10,323,360
		Distributor of Natural/Organic Foods to Grocery Stores

Number of Shares			Value
		> Food & Beverage 0.1%
	1,315,000	GLG Life Tech (Canada) (a)	$	327,050
		Producer of an All-natural Sweetener Extracted from the Stevia Plant
Consumer Goods & Services: Total				65,308,973
Health Care 8.1%
		> Medical Supplies 4.5%
	243,000	Cepheid (a)		13,826,700
		Molecular Diagnostics
	325,000	VWR (a)		8,446,750
		Distributor of Lab Supplies
	41,000	Henry Schein (a)		5,724,420
		Distributor of Dental, Vet & Medical Products
				27,997,870
		> Biotechnology & Drug Delivery 3.6%
	121,769	Synageva BioPharma (a)(b)		11,876,131
		Biotech Focused on Orphan Diseases
	91,000	Ultragenyx Pharmaceutical (a)		5,650,190
		Biotech Focused on "Ultra-Orphan" Drugs
	148,000	Seattle Genetics (a)		5,231,800
		Antibody-based Therapies for Cancer
				22,758,121
Health Care: Total				50,755,991
Energy & Minerals 6.7%
		> Agricultural Commodities 3.1%
	1,742,424	Union Agriculture Group (Uruguay) (a)(c)(d)		18,974,997
		Farmland Operator in Uruguay
		> Oil & Gas Producers 2.0%
	106,000	Carrizo Oil & Gas (a)		5,262,900
		Oil & Gas Producer
	45,000	Cimarex Energy		5,179,050
		Oil & Gas Producer in Texas, New Mexico & Oklahoma
	22,500,000	Canadian Overseas Petroleum (Canada) (a)(d)(e)		1,392,316
		Oil & Gas Exploration Offshore West Africa
	16,000,000	Petromanas (Canada) (a)(b)		631,637
		Exploring for Oil in Albania
	3,036,000	Petrodorado Energy (Colombia) (a)(e)		239,706
		Oil & Gas Exploration & Production in Colombia, Peru & Paraguay
				12,705,609
		> Oil Services 0.8%
	109,000	Gulfport Energy (a)		5,004,190
		Oil & Gas Producer Focused on Utica Shale in Ohio
		> Mining 0.8%
	47,000	Core Labs (Netherlands) (b)		4,911,030
		Oil & Gas Reservoir Consulting
Energy & Minerals: Total				41,595,826

Number of Shares			Value
Other Industries 5.2%
		> Real Estate 5.2%
	166,000	Extra Space Storage	$	11,216,620
		Self Storage Facilities
	197,000	Post Properties		11,215,210
		Multifamily Properties
	275,000	EdR		9,729,500
		Student Housing
				32,161,330
Other Industries: Total				32,161,330
Total Equities: 97.7% (Cost: $435,570,795)				609,024,060	(f)
Short-Term Investments 2.6%
	16,316,617	JPMorgan U.S. Government Money Market Fund, Agency Shares (7 day yield of 0.01%)		16,316,617
Total Short-Term Investments: 2.6% (Cost: $16,316,617)				16,316,617
Securities Lending Collateral 1.0%
	6,411,300	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (g)		6,411,300
Total Securities Lending Collateral: 1.0% (Cost: $6,411,300)				6,411,300
Total Investments: 101.3% (Cost: $458,298,712)(h)				631,751,977	(i)
Obligation to Return Collateral for Securities Loaned: (1.0)%				(6,411,300	)
Cash and Other Assets Less Liabilities: (0.3)%				(1,843,478	)
Net Assets: 100.0%			$	623,497,199

ADR - American Depositary Receipts

COLUMBIA ACORN SELECT^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

(a) Non-income producing security.

(b) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $6,198,822.

(d) Denotes a restricted security, which is subject to restrictions on resale under federal securities laws. These securities are valued at fair value determined in good faith under consistently applied procedures established by the Fund's Board of Trustees. At March 31, 2015, the market value of these securities amounted to $20,367,313, which represented 3.27% of total net assets. Additional information on these securities is as follows:

Security	Acquisition Dates	Shares/Units		Cost		Value
Union Agriculture Group	12/8/10-6/27/12		1,742,424	$	20,000,000	$	18,974,997
Canadian Overseas Petroleum	11/24/10		22,500,000		9,596,330		1,392,316
				$	29,596,330	$	20,367,313

(e) An affiliated person of the Fund, as defined in the Investment Company Act of 1940, may include any company in which the Fund owns five percent or more of its outstanding voting shares. Holdings and transactions in these affiliated companies during the period ended March 31, 2015, are as follows:

Security	Balance of Shares Held 12/31/14		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 3/31/15		Value		Dividend
Canadian Overseas Petroleum		22,500,000		-		-		22,500,000	$	1,392,316	$	-
Petrodorado Energy		3,370,000		-		334,000		3,036,000		239,706		-
Total of Affiliated Transactions		25,870,000		-		334,000		25,536,000	$	1,632,022	$	-

The aggregate cost and value of these companies at March 31, 2015, was $20,784,680 and $1,632,022, respectively. Investments in affiliated companies represented 0.26% of the Fund's total net assets at March 31, 2015.

(f) On March 31, 2015, the market value of foreign securities represented 4.25% of total net assets. The Fund's foreign portfolio was diversified as follows:

Country	Value		Percentage of Net Assets
Uruguay	$	18,974,997		3.04
Netherlands		4,911,030		0.79
Canada		2,351,003		0.38
Colombia		239,706		0.04
Total Foreign Portfolio	$	26,476,736		4.25

(g) Investment made with cash collateral received from securities lending activity.

(h) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $458,298,712 and net unrealized appreciation was $173,453,265 consisting of gross unrealized appreciation of $208,526,283 and gross unrealized depreciation of $35,073,018.

(i) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

> Notes to Statement of Investments

procedures of the investment manager (the Policies), and to review the continuing appropriateness of the current value of any security subject to the Policies. The Policies address, among other things: circumstances under which market quotations will be deemed readily available; selection of third party pricing vendors; appropriate pricing methodologies; events that require fair valuation and fair value techniques; circumstances under which securities will be deemed to pose a potential for stale pricing, including when securities are illiquid, restricted, or in default; and certain delegations of authority to determine fair values to the Fund's investment manager. The Committee may also meet to discuss additional valuation matters, which may include review of back-testing results, review of time-sensitive information or approval of other valuation related actions, and to review the appropriateness of the Policies.

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Industrial Goods & Services	$	173,053,700	$	-	$	-	$	173,053,700
Information		171,212,420		-		-		171,212,420
Finance		74,935,820		-		-		74,935,820
Consumer Goods & Services		65,308,973		-		-		65,308,973
Health Care		50,755,991		-		-		50,755,991
Energy & Minerals		21,228,513		1,392,316		18,974,997		41,595,826
Other Industries		32,161,330		-		-		32,161,330
Total Equities		588,656,747		1,392,316		18,974,997		609,024,060
Total Short-Term Investments		16,316,617		-		-		16,316,617
Total Securities Lending Collateral		6,411,300		-		-		6,411,300
Total Investments	$	611,384,664	$	1,392,316	$	18,974,997	$	631,751,977

There were no transfers of financial assets between levels during the period.

The following table reconciles asset balances for the period ending March 31, 2015, in which significant observable and/or unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2014		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)		Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of March 31, 2015
Equities
Energy & Minerals	$	15,908,331	$	-	$	3,066,666	$	-	$	-	$	-	$	-	$	18,974,997

The information in the above reconciliation table represents fiscal year to date activity for any securities identified as using Level 3 inputs at either the beginning or the end of the current fiscal period.

The change in unrealized appreciation attributed to securities owned at March 31, 2015, which were valued using significant unobservable inputs (Level 3), amounted to $3,066,666.

COLUMBIA ACORN SELECT^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

Quantitative information pertaining to Level 3 unobservable fair value measurements

Fair Value at
March 31, 2015

Valuation Technique(s)

Unobservable Input(s)

Range (Weighted
Average)

Equities

Energy & Minerals

18,974,997

Market comparable companies

Discount for lack of marketability

% to 23%

COLUMBIA THERMOSTAT FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
		> Affiliated Bond Funds 89.7%
	44,390,962	Columbia Short Term Bond Fund, Class I (a)	$	442,133,980
	29,765,306	Columbia Intermediate Bond Fund, Class I (a)		277,115,001
	21,998,052	Columbia Income Opportunities Fund, Class I (a)		221,740,366
	29,925,334	Columbia U.S. Government Mortgage Fund, Class I (a)		166,085,604
Total Affiliated Bond Funds: (Cost: $1,092,874,322)				1,107,074,951
		> Affiliated Stock Funds 9.9%
	562,762	Columbia Acorn International, Class I (a)		24,530,805
	1,296,966	Columbia Dividend Income Fund, Class I (a)		24,357,023
	551,616	Columbia Acorn Fund, Class I (a)(b)		18,374,326
	831,211	Columbia Contrarian Core Fund, Class I (a)		18,203,519
	533,606	Columbia Acorn Select, Class I (a)(b)		12,288,941
	564,010	Columbia Large Cap Enhanced Core Fund, Class I (a)		12,182,612
	634,659	Columbia Select Large Cap Growth Fund, Class I (a)(b)		12,064,869
Total Affiliated Stock Funds: (Cost: $88,174,334)				122,002,095

Number of Shares			Value
		> Short-Term Investments 0.3%
	4,155,573	JPMorgan U.S. Government Money Market Fund, Agency Shares (7 day yield of 0.01%)	$	4,155,573
Total Short-Term Investments: (Cost: $4,155,573)				4,155,573
Total Investments: 99.9% (Cost: $1,185,204,229)(c)				1,233,232,619	(d)
Cash and Other Assets Less Liabilities: 0.1%				1,228,809
Net Assets: 100.0%			$	1,234,461,428

> Notes to Statement of Investments

(a) An affiliated person of the Fund, as defined in the Investment Company Act of 1940, may include any company in which the Fund owns five percent or more of its outstanding voting shares. Holdings and transactions in these affiliated companies during the period ended March 31, 2015, are as follows:

Security	Balance of Shares Held 12/31/14		Purchases/ Additions		Sales/ Reductions		Balance of Shares Held 3/31/15		Value		Dividend
Columbia Short Term Bond Fund, Class I		42,849,246		2,448,736		907,020		44,390,962	$	442,133,980	$	1,205,740
Columbia Intermediate Bond Fund, Class I		28,994,280		1,711,274		940,248		29,765,306		277,115,001		2,018,327
Columbia Income Opportunities Fund, Class I		21,780,174		1,364,586		1,146,708		21,998,052		221,740,366		2,647,214
Columbia U.S. Government Mortgage Fund, Class I		28,883,507		1,814,285		772,458		29,925,334		166,085,604		1,207,571
Columbia Acorn International, Class I		898,450		-		335,688		562,762		24,530,805		-
Columbia Dividend Income Fund, Class I		1,962,468		8,696		674,198		1,296,966		24,357,023		166,261
Columbia Acorn Fund, Class I		879,308		-		327,692		551,616		18,374,326		-
Columbia Contrarian Core Fund, Class I		1,291,662		-		460,451		831,211		18,203,519		-
Columbia Acorn Select, Class I		836,113		-		302,507		533,606		12,288,941		-
Columbia Large Cap Enhanced Core Fund, Class I		870,296		-		306,286		564,010		12,182,612		-
Columbia Select Large Cap Growth Fund, Class I		1,023,561		-		388,902		634,659		12,064,869		-
Total of Affiliated Transactions		130,269,065		7,347,577		6,562,158		131,054,484	$	1,229,077,046	$	7,245,113

The aggregate cost and value of these companies at March 31, 2015, was $1,181,048,656 and $1,229,077,046 respectively. Investments in affiliated companies represented 99.56% of the Fund's total net assets at March 31, 2015.

(b) Non-income producing security.

(c) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $1,185,204,229 and net unrealized appreciation was $48,028,390 consisting of gross unrealized appreciation of $48,654,804 and gross unrealized depreciation of $626,414.

(d) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

COLUMBIA THERMOSTAT FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Examples of the types of securities in which the Fund would typically invest and how they are classified within this hierarchy are as follows. Typical Level 1 securities include mutual funds whose NAVs are published each day.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Total Affiliated Bond Funds	$	1,107,074,951	$	-	$	-	$	1,107,074,951
Total Affiliated Stock Funds		122,002,095		-		-		122,002,095
Total Short-Term Investments		4,155,573		-		-		4,155,573
Total Investments	$	1,233,232,619	$	-	$	-	$	1,233,232,619

There were no transfers of financial assets between levels during the period.

COLUMBIA ACORN EMERGING MARKETS FUND^SM

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Asia
> Taiwan
President Chain Store		1,058,000		1,240,000
Voltronic Power		0		404,000
> China
AMVIG Holdings		30,774,000		31,000,000
BitAuto - ADR		114,558		126,580
China Everbright International		0		3,128,000
Sino Biopharmaceutical		0		4,925,000
Xinhua Winshare Publishing		0		2,146,000
> India
Bharti Infratel		0		730,342
Container Corporation of India		0		140,070
> Indonesia
Mayora Indah		2,183,600		2,300,000
> Philippines
Melco Crown (Philippines) Resorts		39,172,300		41,313,300
> Korea
The Basic House		358,365		421,000
> Hong Kong
Melco International		5,181,000		5,817,000
> Malaysia
7-Eleven Malaysia Holdings		10,810,900		12,777,900
Astro Malaysia Holdings		0		114,500
Europe
> United Kingdom
PureCircle		544,900		580,790
> France
Eutelsat		161,154		200,000
Latin America
> Brazil
Linx		255,000		280,000
Localiza Rent A Car		557,970		677,970
> Mexico
Qualitas		2,069,000		2,500,000
Other Countries
> Egypt
Commercial International Bank of Egypt		0		593,000

	Number of Shares
	12/31/14		3/31/15
Sales
Asia
> Taiwan
Advantech		720,988		598,988
Largan Precision		71,000		55,000
Vanguard International Semiconductor		3,461,000		2,814,000
> China
WuXi PharmaTech - ADR		307,909		121,000
> India
United Breweries		419,349		353,739
> Indonesia
Matahari Department Store		6,909,600		4,248,600
MNC Sky Vision		61,966,600		61,839,700
> Philippines
Puregold Price Club		8,198,200		5,613,200
Robinsons Retail Holdings		3,814,910		2,636,090
Security Bank		1,601,770		0
> Korea
Grand Korea Leisure		132,149		98,149
Koh Young Technology		295,533		256,088
Paradise		121,818		0
> Hong Kong
Sa Sa International		7,471,799		5,583,799
> Malaysia
Aeon		4,592,100		4,006,700
Europe
> Sweden
Hexagon		288,064		207,455
> Italy
Pirelli		393,882		270,882
> Turkey
Aviva		54,624		0
Latin America
> Brazil
Beadell Resources		3,663,018		335,646
> Mexico
Genomma Lab International		2,278,100		0
Other Countries
> South Africa
Coronation Fund Managers		2,003,746		1,955,513
Rand Merchant Insurance		2,851,148		2,599,148
> Morocco
Holcim Maroc		4,273		0

COLUMBIA ACORN EMERGING MARKETS FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 97.1%
Asia 65.6%
		> Taiwan 11.3%
	1,240,000	President Chain Store	$	9,320,016
		Convenience Chain Store Operator in Taiwan
	570,000	PChome Online		7,402,954
		Taiwanese Internet Retail Company
	420,000	St. Shine Optical		6,760,821
		Disposable Contact Lens Original Equipment Manufacturer
	2,050,990	Chroma Ate		5,089,432
		Automatic Test Systems, Testing & Measurement Instruments
	2,814,000	Vanguard International Semiconductor		4,776,686
		Semiconductor Foundry
	55,000	Largan Precision		4,728,239
		Mobile Device Camera Lenses & Modules
	598,988	Advantech		4,554,748
		Industrial PC & Components
	360,000	Ginko International		4,135,832
		Contact Lens Maker in China
	404,000	Voltronic Power		3,999,827
		Uninterruptible Power Supply Products
				50,768,555
		> China 11.3%
	31,000,000	AMVIG Holdings		13,835,269
		Chinese Tobacco Packaging Material Supplier
	126,580	BitAuto - ADR (a)		6,440,390
		Automotive Information Website for Buyers & Dealers
	11,951,000	Sihuan Pharmaceuticals (b)		6,337,233
		Chinese Generic Drug Manufacturer
	11,330,000	NewOcean Energy		5,602,784
		Southern China Liquefied Petroleum Gas Distributor
	3,128,000	China Everbright International		5,246,275
		Private Municipal Waste Operator
	4,925,000	Sino Biopharmaceutical		4,982,540
		Pharmaceutical Developer
	121,000	WuXi PharmaTech - ADR (a)		4,692,380
		Contract Research Organization in China
	2,146,000	Xinhua Winshare Publishing		2,091,010
		Sichuan Publisher, Distributor & Retailer
	257,000	Phoenix New Media - ADR (a)		1,457,190
		Internet Advertising
				50,685,071
		> India 10.8%
	2,422,982	Zee Entertainment Enterprises		13,230,862
		Indian Programmer of Pay Television Content
	1,737,269	Adani Ports & Special Economic Zone		8,554,109
		Indian West Coast Shipping Port

Number of Shares			Value
	17,632	Bosch	$	7,162,357
		Automotive Parts
	190,350	Colgate Palmolive India		6,124,490
		Consumer Products in Oral Care
	353,739	United Breweries		5,653,091
		Indian Brewer
	730,342	Bharti Infratel		4,493,066
		Communications Towers
	140,070	Container Corporation of India		3,543,540
		Railway Cargo Services
				48,761,515
		> Indonesia 8.5%
	61,839,700	MNC Sky Vision (a)		7,803,863
		Satellite Pay TV Operator in Indonesia
	4,248,600	Matahari Department Store		6,389,108
		Department Store Chain in Indonesia
	11,800,000	Link Net (a)		5,392,352
		Fixed Broadband & CATV Service Provider
	2,300,000	Mayora Indah		5,078,375
		Consumer Branded Food Manufacturer
	6,744,300	Tower Bersama Infrastructure		4,887,361
		Communications Towers
	82,889,190	Ace Indonesia		4,657,585
		Home Improvement Retailer
	66,827,700	Arwana Citramulia		4,139,995
		Ceramic Tiles for Home Decoration
				38,348,639
		> Philippines 5.6%
	41,313,300	Melco Crown (Philippines) Resorts (a)(c)		8,463,391
		Integrated Resort Operator in Manila
	56,400,000	RFM Corporation		6,677,236
		Flour, Bread, Pasta & Ice Cream Manufacturer/Distributor in the Philippines
	5,613,200	Puregold Price Club		5,215,288
		Supermarket Operator in the Philippines
	2,636,090	Robinsons Retail Holdings		4,953,726
		Multi-format Retailer in the Philippines
				25,309,641
		> Korea 4.3%
	256,088	Koh Young Technology		10,252,917
		Inspection Systems for Printed Circuit Boards
	421,000	The Basic House (a)		5,868,287
		Casual & Formal Apparel in China
	98,149	Grand Korea Leisure		3,341,148
		'Foreigner Only' Casino Group in Korea
				19,462,352
		> Hong Kong 4.1%
	5,817,000	Melco International		9,788,675
		Macau Casino Operator
	3,698,000	Vitasoy International		5,781,218
		Hong Kong Soy Food Brand

Number of Shares			Value
		> Hong Kong—continued
	5,583,799	Sa Sa International (c)	$	2,729,928
		Cosmetics Retailer
				18,299,821
		> Thailand 3.6%
	3,737,700	Robinson Department Store		5,454,294
		Department Store Operator in Thailand
	10,016,800	Samui Airport Property Fund		5,294,682
		Thai Airport Operator
	21,126,235	Home Product Center		5,291,298
		Home Improvement Retailer
				16,040,274
		> Malaysia 2.0%
	12,777,900	7-Eleven Malaysia Holdings		5,520,357
		Exclusive 7-Eleven Franchisor for Malaysia
	4,006,700	Aeon		3,198,692
		Shopping Center & Department Store Operator
	114,500	Astro Malaysia Holdings		98,773
		Largest Pay TV Operator in Malaysia
				8,817,822
		> Cambodia 1.7%
	11,570,000	Nagacorp		7,681,991
		Casino & Entertainment Complex in Cambodia
		> Japan 1.3%
	310,760	Kansai Paint		5,655,759
		Paint Producer in Japan, India, China & Southeast Asia
		> Singapore 1.1%
	1,829,000	Petra Foods		5,089,850
		Chocolate Manufacturer in Southeast Asia
Asia: Total				294,921,290
Europe 11.9%
		> United Kingdom 3.0%
	10,175,965	Cable and Wireless		9,176,568
		Telecommunications Service Provider in the Caribbean
	580,790	PureCircle (a)(c)		4,458,490
		Natural Sweeteners
				13,635,058
		> Kazakhstan 2.1%
	1,268,483	Halyk Savings Bank of Kazakhstan - GDR		9,374,090
		Retail Bank & Insurer in Kazakhstan
		> Sweden 1.6%
	207,455	Hexagon		7,365,708
		Design, Measurement & Visualization Software & Equipment
		> France 1.5%
	200,000	Eutelsat		6,634,251
		Fixed Satellite Services

Number of Shares			Value
		> Spain 1.5%
	1,148,390	Prosegur	$	6,539,914
		Security Guards
		> Finland 1.2%
	290,000	Tikkurila		5,530,066
		Decorative & Industrial Paint in Scandinavia, Central & Eastern Europe
		> Italy 1.0%
	270,882	Pirelli		4,483,836
		Global Tire Supplier
Europe: Total				53,562,923
Latin America 10.3%
		> Brazil 3.7%
	677,970	Localiza Rent A Car		7,770,564
		Car Rental
	1,430,100	Odontoprev		4,906,580
		Dental Insurance
	280,000	Linx		4,084,786
		Retail Management Software in Brazil
	335,646	Beadell Resources		65,598
		Gold Mining in Brazil
				16,827,528
		> Mexico 3.2%
	40,525	Grupo Aeroportuario del Sureste - ADR (a)		5,447,370
		Mexican Airport Operator
	2,500,000	Qualitas (a)		4,523,552
		Auto Insurer in Mexico & Central America
	2,747,000	Hoteles City Express (a)		4,178,084
		Leading Budget Hotel Operator in Mexico
				14,149,006
		> Chile 1.8%
	1,943,078	Forus		8,010,335
		Multi-brand Latin American Wholesaler & Retailer
		> Colombia 1.6%
	6,047,782	Isagen		7,094,514
		Colombian Electricity Provider
Latin America: Total				46,081,383
Other Countries 9.3%
		> South Africa 7.1%
	1,955,513	Coronation Fund Managers		15,806,352
		South African Fund Manager
	2,599,148	Rand Merchant Insurance		9,897,360
		Directly Sold Property & Casualty Insurance; Holdings in other Insurers
	288,041	Mr. Price		6,160,654
		South African Retailer of Apparel, Household & Sporting Goods
				31,864,366
		> United States 1.2%
	171,094	Bladex		5,610,172
		Latin American Trade Financing House

COLUMBIA ACORN EMERGING MARKETS FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

Number of Shares			Value
		> Egypt 1.0%
	593,000	Commercial International Bank of Egypt	$	4,371,369
		Leading Private Universal Bank in Egypt
Other Countries: Total				41,845,907
Total Equities: 97.1% (Cost: $423,179,204)				436,411,503	(d)
Short-Term Investments 2.3%
	10,363,888	JPMorgan U.S. Government Money Market Fund, IM Shares (7 day yield of 0.01%)		10,363,888
Total Short-Term Investments: 2.3% (Cost: $10,363,888)				10,363,888

Number of Shares			Value
Securities Lending Collateral 0.6%
	2,592,411	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (e)	$	2,592,411
Total Securities Lending Collateral: 0.6% (Cost: $2,592,411)				2,592,411
Total Investments: 100.0% (Cost: $436,135,503)(f)				449,367,802	(g)
Obligation to Return Collateral for Securities Loaned: (0.6)%				(2,592,411	)
Cash and Other Assets Less Liabilities: 0.6%				2,533,169
Net Assets: 100.0%			$	449,308,560

ADR - American Depositary Receipts

GDR - Global Depositary Receipts

> Notes to Statement of Investments

(a) Non-income producing security.

(b) Illiquid security.

(c) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $2,402,594.

(d) On March 31, 2015, the Fund's total equity investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Hong Kong Dollar	$	64,076,922		14.3
Taiwan Dollar		50,768,556		11.3
Indian Rupee		48,761,515		10.9
Indonesian Rupiah		38,348,639		8.5
U.S. Dollar		33,021,593		7.3
South African Rand		31,864,366		7.1
Philippines Peso		25,309,641		5.6
Euro		23,188,067		5.2
Other currencies less than 5% of total net assets		121,072,204		26.9
Total Equities	$	436,411,503		97.1

(e) Investment made with cash collateral received from securities lending activity.

(f) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $436,135,503 and net unrealized appreciation was $13,232,299 consisting of gross unrealized appreciation of $57,882,801 and gross unrealized depreciation of $44,650,502.

(g) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

> Notes to Statement of Investments

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Asia	$	12,589,960	$	275,994,097	$	6,337,233	$	294,921,290
Europe		-		53,562,923		-		53,562,923
Latin America		46,015,785		65,598		-		46,081,383
Other Countries		5,610,172		36,235,735		-		41,845,907
Total Equities		64,215,917		365,858,353		6,337,233		436,411,503
Total Short-Term Investments		10,363,888		-		-		10,363,888
Total Securities Lending Collateral		2,592,411		-		-		2,592,411
Total Investments	$	77,172,216	$	365,858,353	$	6,337,233	$	449,367,802

The following table shows transfers between Level 2 and Level 3 of the fair value hierarchy:

Transfers In				Transfers Out
Level 2		Level 3		Level 2		Level 3
$	-	$	7,949,312	$	7,949,312	$	-

COLUMBIA ACORN EMERGING MARKETS FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

The following table reconciles asset balances for the period ending March 31, 2015, in which significant observable and/or unobservable inputs (Level 3) were used in determining value:

Investments in Securities	Balance as of December 31, 2014		Realized Gain/(Loss)		Change in Unrealized Appreciation (Depreciation)			Purchases		Sales		Transfers into Level 3		Transfers out of Level 3		Balance as of March 31, 2015
Equities
Asia	$	-	$	-	$	(1,612,079	)	$	-	$	-	$	7,949,312	$	-	$	6,337,233

The change in unrealized depreciation attributed to securities owned at March 31, 2015, which were valued using significant unobservable inputs (Level 3), amounted to $1,612,079.

Quantitative information pertaining to Level 3 unobservable fair value measurements

Fair Value at
March 31, 2015

Valuation Technique(s)

Unobservable Input(s)

Range (Weighted
Average)

Equities

Asia

6,337,233

Market comparable companies

Discount for lack of marketability

Certain securities classified as Level 3 are valued at fair value, using a market approach, as determined in good faith under consistently applied procedures established by and under the general supervision of the Board. To determine fair value for these securities, for which no market exists, the Committee utilizes the valuation technique it deems most appropriate in the circumstances, using some unobservable inputs, which may include, but are not limited to estimated earnings of the company and the position of the security within the company's capital structure. The Committee also may use some observable inputs, which may include, but are not limited to, trades of similar securities or indicies. Significant increases or decreases to any of these inputs could result in a significantly lower or higher fair value measurement.

COLUMBIA ACORN EMERGING MARKETS FUND^SM

PORTFOLIO DIVERSIFICATION (UNAUDITED)

At March 31, 2015, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value		Percentage of Net Assets
> Consumer Goods & Services
Retail	$	76,395,243		17.0
Food & Beverage		32,738,260		7.3
Casinos & Gaming		29,275,205		6.5
Travel		11,948,647		2.6
Consumer Goods Distribution		6,124,490		1.4
Apparel		5,868,288		1.3
Other Durable Goods		4,483,836		1.0
		166,833,969		37.1
> Information
Instrumentation		15,342,349		3.4
Satellite Broadcasting & Services		14,536,887		3.2
Entertainment Programming		13,230,863		3.0
Business Software		11,450,495		2.5
Mobile Communications		9,380,427		2.1
Telephone & Data Services		9,176,568		2.0
Computer Hardware & Related Equipment		8,554,575		1.9
Internet Related		7,897,580		1.8
Cable TV		5,392,352		1.2
Semiconductors & Related Equipment		4,776,686		1.1
Telecommunications Equipment		4,728,239		1.1
		104,467,021		23.3
> Industrial Goods & Services
Industrial Materials & Specialty Chemicals		29,161,089		6.5
Other Industrial Services		8,554,109		1.9
Machinery		7,162,357		1.6
Outsourcing Services		6,539,914		1.4
Waste Management		5,246,275		1.2
		56,663,744		12.6
> Finance
Banks		19,355,631		4.3
Insurance		19,327,491		4.3
Brokerage & Money Management		15,806,352		3.5
		54,489,474		12.1
> Health Care
Pharmaceuticals		16,012,153		3.6
Medical Supplies		10,896,654		2.4
		26,908,807		6.0

	Value			Percentage of Net Assets
> Other Industries
Transportation	$	14,285,593			3.2
Regulated Utilities		7,094,513			1.6
		21,380,106			4.8
> Energy & Minerals
Oil Refining, Marketing & Distribution		5,602,784			1.2
Mining		65,598			0.0	*
		5,668,382			1.2
Total Equities:		436,411,503			97.1
Short-Term Investments:		10,363,888			2.3
Securities Lending Collateral:		2,592,411			0.6
Total Investments:		449,367,802			100.0
Obligation to Return Collateral for Securities Loaned:		(2,592,411	)		(0.6	)
Cash and Other Assets Less Liabilities:		2,533,169			0.6
Net Assets:	$	449,308,560			100.0

* Rounds to zero.

COLUMBIA ACORN EUROPEAN FUND^SM

MAJOR PORTFOLIO CHANGES IN THE FIRST QUARTER (UNAUDITED)

	Number of Shares
	12/31/14		3/31/15
Purchases
Europe
> United Kingdom
Abcam		61,730		63,970
Aggreko		16,633		26,960
AVEVA		16,930		18,550
Babcock International		45,240		56,990
Cable and Wireless		505,313		950,000
Cambian		145,820		199,280
Charles Taylor		188,030		241,240
Dialight		31,910		55,260
Elementis		89,680		95,860
Fidessa Group		10,300		18,470
Halfords		49,530		76,159
Polypipe		100,890		101,620
PureCircle		42,232		53,548
RPS Group		101,810		120,090
WH Smith		32,210		32,710
Whitbread		5,575		7,954
> France
Bonduelle		15,320		15,690
Eutelsat		12,505		18,960
Hi-Media		123,020		174,500
> Germany
Aurelius		22,450		23,640
Elringklinger		12,580		13,410
MTU Aero Engines		4,410		7,000
Wirecard		14,240		14,360
> Sweden
Hexagon		18,910		21,733
Mekonomen		16,400		18,960
Modern Times Group		0		16,160
Recipharm		28,950		29,580
Sweco		31,870		41,270
Unibet		7,351		11,851
> Spain
Distribuidora Internacional de Alimentación		123,060		169,200
Prosegur		100,660		109,950
Viscofan		10,000		10,430
> Netherlands
Arcadis		11,819		12,819
Brunel		16,071		27,271
Core Labs		1,960		3,920
Gemalto		4,760		5,490

	Number of Shares
	12/31/14		3/31/15
> Finland
Konecranes		12,580		15,240
Munksjo		63,850		68,380
Sponda		101,200		123,070
Tikkurila		25,341		28,801
> Switzerland
Geberit		2,290		2,740
> Norway
Atea		32,400		36,180
Orkla		58,530		70,370
> Belgium
EVS Broadcast Equipment		10,920		11,070

	Number of Shares
	12/31/14		3/31/15
Sales
Europe
> United Kingdom
Jardine Lloyd Thompson Group		40,000		38,560
Rightmove		11,210		9,670
Spirax Sarco		21,120		20,450
> France
Eurofins Scientific		2,390		1,540
> Germany
NORMA Group		16,790		16,360
Telefonica Deutschland		80,330		70,780
> Sweden
Swedish Match		19,320		17,970
> Netherlands
Aalberts Industries		26,960		26,330
> Switzerland
INFICON		1,250		1,150
Partners Group		3,570		3,250
> Norway
Subsea 7		33,440		0
> Italy
Pirelli		29,520		24,990
> Denmark
Jyske Bank		7,260		0

COLUMBIA ACORN EUROPEAN FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), MARCH 31, 2015

Number of Shares			Value
			Equities: 96.8%
Europe 96.8%
		> United Kingdom 34.9%
	1,667,855	Assura	$	1,540,125
		UK Primary Health Care Property Developer
	20,450	Spirax Sarco		1,034,045
		Steam Systems for Manufacturing & Process Industries
	241,240	Charles Taylor		797,123
	96,338	Charles Taylor - Rights		95,034
		Insurance Services
	950,000	Cable and Wireless		856,699
		Telecommunications Service Provider in the Caribbean
	56,990	Babcock International		831,362
		Public Sector Outsourcer
	199,280	Cambian (a)		688,776
		Mental Health Facilities & Programs
	32,710	WH Smith		628,502
		Newsprint, Books & General Stationery Retailer
	55,260	Dialight		622,288
		LED Products for Hazardous & Industrial Environments
	7,954	Whitbread		617,627
		UK Hotelier & Coffee Shop
	26,960	Aggreko		609,849
		Temporary Power & Temperature Control Services
	18,470	Fidessa Group		604,409
		Software for Financial Trading Systems
	38,560	Jardine Lloyd Thompson Group		598,883
		International Business Insurance Broker
	76,159	Halfords		518,505
		UK Retailer of Leisure Goods & Auto Parts
	225,231	Connect Group		515,361
		Newspaper & Magazine Distributor
	92,240	Ocado (a)		480,689
		Online Grocery Retailer
	63,970	Abcam		459,493
		Online Sales of Antibodies
	37,830	Domino's Pizza UK & Ireland		434,974
		Pizza Delivery in the UK, Ireland & Germany
	9,670	Rightmove		428,997
		Internet Real Estate Listings
	101,620	Polypipe		415,258
		Manufacturer of Plastic Piping & Fittings
	95,860	Elementis		411,753
		Specialty Chemicals
	53,548	PureCircle (a)(b)		411,066
		Natural Sweeteners
	39,570	Halma		408,853
		Health & Safety Sensor Technology
	18,550	AVEVA		405,492
		Engineering Software
	120,090	RPS Group		401,353
		Consultant Specializing in Energy, Water, Urban Planning, Health & Safety
				14,816,516

Number of Shares			Value
		> France 10.8%
	16,720	Neopost	$	919,584
		Postage Meter Machines
	18,960	Eutelsat		628,927
		Fixed Satellite Services
	14,480	Cegedim (a)		490,443
		Medical Market Research/IT Services
	12,681	Saft		463,448
		Niche Battery Manufacturer
	2,690	Norbert Dentressangle		455,243
		European Logistics & Transport Group
	1,540	Eurofins Scientific		414,488
		Food, Pharmaceuticals & Materials Screening & Testing
	174,500	Hi-Media (a)(b)		412,789
		Online Advertiser in Europe
	12,613	AKKA Technologies		407,000
		Engineering Consultancy
	15,690	Bonduelle		404,917
		Producer of Canned, Deep-frozen & Fresh Vegetables
				4,596,839
		> Germany 10.2%
	23,640	Aurelius		987,252
		European Turnaround Investor
	16,360	NORMA Group		821,386
		Clamps for Automotive & Industrial Applications
	7,000	MTU Aero Engines		685,785
		Airplane Engine Components & Services
	14,360	Wirecard		605,205
		Online Payment Processing & Risk Management
	70,780	Telefonica Deutschland		407,015
		Mobile & Fixed-line Communications in Germany
	13,410	Elringklinger		402,039
		Automobile Components
	1,200	Rational		401,115
		Commercial Ovens
				4,309,797
		> Sweden 9.7%
	21,733	Hexagon		771,632
		Design, Measurement & Visualization Software & Equipment
	11,851	Unibet		650,198
		European Online Gaming Operator
	29,580	Recipharm (a)		630,264
		Contract Development Manufacturing Organization
	41,270	Sweco		529,562
		Engineering Consultants
	17,970	Swedish Match		528,366
		Swedish Snus
	18,960	Mekonomen		500,851
		Nordic Integrated Wholesaler/Retailer of Automotive Parts & Service
	16,160	Modern Times Group		494,880
		Leading Nordic TV Broadcaster
	90	Trelleborg		1,780
		Manufacturer of Sealing, Dampening & Protective Solutions for Industry
				4,107,533

Number of Shares			Value
		> Spain 7.2%
	169,200	Distribuidora Internacional de Alimentación	$	1,320,431
		Discount Retailer in Spain & Latin America
	10,430	Viscofan		637,258
		Sausage Casings Maker
	109,950	Prosegur		626,149
		Security Guards
	10,370	Bolsas y Mercados Españoles		461,809
		Spanish Stock Markets
				3,045,647
		> Netherlands 6.1%
	26,330	Aalberts Industries		828,670
		Flow Control & Heat Treatment
	27,271	Brunel		521,651
		Temporary Specialist & Energy Staffing
	5,490	Gemalto		437,434
		Digital Security Solutions
	12,819	Arcadis		411,681
		Engineering Consultants
	3,920	Core Labs		409,601
		Oil & Gas Reservoir Consulting
				2,609,037
		> Finland 5.7%
	58,000	Munksjo (a)		738,396
	10,380	Munksjo (a)(c)		130,169
		Specialty Paper Maker
	28,801	Tikkurila		549,212
		Decorative & Industrial Paint in Scandinavia, Central & Eastern Europe
	123,070	Sponda		528,122
		Office, Retail & Logistics Properties
	15,240	Konecranes		480,228
		Manufacture & Service of Industrial Cranes & Port Handling Equipment
				2,426,127
		> Switzerland 5.7%
	2,740	Geberit		1,025,351
		Plumbing Supplies
	3,250	Partners Group		968,914
		Private Markets Asset Management
	1,150	INFICON		410,925
		Gas Detection Instruments
				2,405,190
		> Norway 2.2%
	70,370	Orkla		531,105
		Food & Brands, Aluminum, Chemicals Conglomerate
	36,180	Atea		407,579
		Nordic IT Hardware/Software Reseller & Integrator
				938,684

Number of Shares			Value
		> Italy 2.1%
	10,240	Industria Macchine Automatiche	$	481,787
		Food & Drugs Packaging & Machinery
	24,990	Pirelli		413,653
		Global Tire Supplier
				895,440
		> Denmark 1.2%
	15,490	SimCorp		508,260
		Software for Investment Managers
		> Belgium 1.0%
	11,070	EVS Broadcast Equipment		412,023
		Digital Live Mobile Production Software & Systems
Europe: Total				41,071,093
Total Equities: 96.8% (Cost: $38,774,821)				41,071,093	(d)
Short-Term Investments 6.9%
	2,906,561	JPMorgan U.S. Government Money Market Fund, IM Shares (7 day yield of 0.01%)		2,906,561
Total Short-Term Investments: 6.9% (Cost: $2,906,561)				2,906,561
Securities Lending Collateral 0.1%
	63,226	Dreyfus Government Cash Management Fund, Institutional Shares (7 day yield of 0.01%) (e)		63,226
Total Securities Lending Collateral: 0.1% (Cost: $63,226)				63,226
Total Investments: 103.8% (Cost: $41,744,608)(f)				44,040,880	(g)
Obligation to Return Collateral for Securities Loaned: (0.1)%				(63,226	)
Cash and Other Assets Less Liabilities: (3.7)%				(1,540,972	)
Net Assets: 100.0%			$	42,436,682

COLUMBIA ACORN EUROPEAN FUND^SM

STATEMENT OF INVESTMENTS (UNAUDITED), CONTINUED

> Notes to Statement of Investments

(a) Non-income producing security.

(b) All or a portion of this security was on loan at March 31, 2015. The total market value of securities on loan at March 31, 2015 was $59,874.

(d) On March 31, 2015, the Fund's total equity investments were denominated in currencies as follows:

Currency	Value		Percentage of Net Assets
Euro	$	17,755,139		41.8
British Pound		14,816,516		34.9
Swedish Krona		4,237,703		10.0
Swiss Franc		2,405,190		5.7
Other currencies less than 5% of total net assets		1,856,545		4.4
Total Equities	$	41,071,093		96.8

(e) Investment made with cash collateral received from securities lending activity.

(f) At March 31, 2015, for federal income tax purposes, the cost of investments was approximately $41,744,608 and net unrealized appreciation was $2,296,272 consisting of gross unrealized appreciation of $4,477,741 and gross unrealized depreciation of $2,181,469.

(g) Securities are valued using policies described in the Notes to Financial Statements in the shareholder report dated December 31, 2014.

Fair Value Measurements

• Level 1 – quoted prices in active markets for identical securities

• Level 2 – prices determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk and others)

The inputs or methodology used for valuing securities are not necessarily an indication of the risk associated with investing in those securities.

Under the direction of the Board, the Committee is responsible for overseeing the valuation procedures approved by the Board.

> Notes to Statement of Investments

The following table summarizes the inputs used, as of March 31, 2015, in valuing the Fund's assets:

Investment Type	Quoted Prices (Level 1)		Other Significant Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total
Equities
Europe	$	409,601	$	40,661,492	$	-	$	41,071,093
Total Equities		409,601		40,661,492		-		41,071,093
Total Short-Term Investments		2,906,561		-		-		2,906,561
Total Securities Lending Collateral		63,226		-		-		63,226
Total Investments	$	3,379,388	$	40,661,492	$	-	$	44,040,880

There were no transfers of financial assets between levels during the period.

COLUMBIA ACORN EUROPEAN FUND^SM

PORTFOLIO DIVERSIFICATION (UNAUDITED)

At March 31, 2015, the Fund's portfolio investments as a percentage of net assets were diversified as follows:

	Value		Percentage of Net Assets
> Industrial Goods & Services
Machinery	$	4,549,071		10.7
Other Industrial Services		3,052,717		7.2
Outsourcing Services		2,386,163		5.6
Conglomerates		2,347,027		5.5
Industrial Materials & Specialty Chemicals		2,233,349		5.3
Construction		1,440,609		3.4
Electrical Components		1,085,736		2.6
		17,094,672		40.3
> Information
Business Software		2,289,793		5.4
Telephone & Data Services		1,263,714		3.0
Computer Services		898,022		2.1
Computer Hardware & Related Equipment		849,457		2.0
Satellite Broadcasting & Services		628,927		1.5
Financial Processors		605,205		1.4
TV Broadcasting		494,880		1.2
Internet Related		428,998		1.0
Advertising		412,789		1.0
Instrumentation		408,853		0.9
		8,280,638		19.5
> Consumer Goods & Services
Retail		3,448,977		8.1
Food & Beverage		1,981,607		4.7
Restaurants		1,052,601		2.5
Casinos & Gaming		650,198		1.5
Consumer Goods Distribution		515,361		1.2
Other Durable Goods		413,653		1.0
		8,062,397		19.0
> Finance
Insurance		1,491,040		3.5
Brokerage & Money Management		968,914		2.3
Financial Processors		461,809		1.1
		2,921,763		6.9
> Other Industries
Real Estate		2,068,247		4.9
Transportation		455,242		1.0
		2,523,489		5.9
> Health Care
Health Care Services		688,776		1.6
Pharmaceuticals		630,264		1.5
Medical Supplies		459,493		1.1
		1,778,533		4.2

	Value			Percentage of Net Assets
> Energy & Minerals
Mining	$	409,601			1.0
		409,601			1.0
Total Equities:		41,071,093			96.8
Short-Term Investments:		2,906,561			6.9
Securities Lending Collateral:		63,226			0.1
Total Investments:		44,040,880			103.8
Obligation to Return Collateral for Securities Loaned:		(63,226	)		(0.1	)
Cash and Other Assets Less Liabilities:		(1,540,972	)		(3.7	)
Net Assets:	$	42,436,682			100.0

COLUMBIA ACORN FAMILY OF FUNDS EXPENSE INFORMATION

as of 3/31/15

Columbia Acorn® Fund	Class A			Class B^(a)			Class C			Class I			Class R			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 Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%					0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.19	%		0.47	%		0.15	%		0.07	%					0.18	%		0.12	%		0.07	%		0.16	%
Net Expense Ratio		1.08	%		1.86	%		1.79	%		0.71	%					0.82	%		0.76	%		0.71	%		0.80	%
Columbia Acorn International®
Management Fees		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%		0.76	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%		0.50	%		0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.22	%		0.55	%		0.21	%		0.09	%		0.35	%		0.29	%		0.14	%		0.09	%		0.18	%
Net Expense Ratio		1.23	%		2.06	%		1.97	%		0.85	%		1.61	%		1.05	%		0.90	%		0.85	%		0.94	%
Columbia Acorn USA®
Management Fees		0.87	%		0.87	%		0.87	%		0.87	%					0.87	%		0.87	%		0.87	%		0.87	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%					0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.22	%		0.85	%		0.14	%		0.05	%					0.22	%		0.13	%		0.08	%		0.21	%
Net Expense Ratio		1.34	%		2.47	%		2.01	%		0.92	%					1.09	%		1.00	%		0.95	%		1.08	%
Columbia Acorn International Select^SM
Management Fees		0.94	%		0.94	%		0.94	%		0.94	%					0.94	%		0.94	%		0.94	%		0.94	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%					0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.33	%		0.51	%		0.34	%		0.26	%					0.30	%		0.23	%		0.17	%		0.26	%
Net Expense Ratio		1.52	%		2.20	%		2.28	%		1.20	%					1.24	%		1.17	%		1.11	%		1.20	%
Columbia Acorn Select^SM
Management Fees		0.85	%		0.85	%		0.85	%		0.85	%					0.85	%		0.85	%		0.85	%		0.85	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%		0.00	%					0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.23	%		0.50	%		0.21	%		0.10	%					0.25	%		0.16	%		0.11	%		0.21	%
Net Expense Ratio		1.33	%		2.10	%		2.06	%		0.95	%					1.10	%		1.01	%		0.96	%		1.06	%
Columbia Thermostat Fund^SM
Management Fees		0.10	%		0.10	%		0.10	%								0.10	%		0.10	%		0.10	%		0.10	%
Distribution and Service (12b-1) Fees		0.25	%		0.75	%		1.00	%								0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.15	%		0.15	%		0.15	%								0.15	%		0.13	%		0.08	%		0.14	%
Net Expense Ratio^(b)		0.50	%		1.00	%		1.25	%								0.25	%		0.23	%		0.18	%		0.24	%
Columbia Acorn Emerging Markets Fund^SM(c)
Management Fees		1.05	%					1.05	%		1.05	%					1.05	%		1.05	%		1.05	%		1.05	%
Distribution and Service (12b-1) Fees		0.25	%					1.00	%		0.00	%					0.00	%		0.00	%		0.00	%		0.00	%
Other Expenses		0.30	%					0.31	%		0.22	%					0.26	%		0.23	%		0.16	%		0.30	%
Net Expense Ratio		1.60	%					2.36	%		1.27	%					1.31	%		1.28	%		1.21	%		1.35	%
Columbia Acorn European Fund^SM
Management Fees		1.19	%					1.19	%		1.19	%					1.19	%		1.19	%					1.19	%
Distribution and Service (12b-1) Fees		0.25	%					1.00	%		0.00	%					0.00	%		0.00	%					0.00	%
Other Expenses		0.31	%					0.31	%		0.28	%					0.31	%		0.33	%					0.31	%
Net Expense Ratio		1.75	%					2.50	%		1.47	%					1.50	%		1.52	%					1.50	%

See the Funds' prospectuses for information on minimum initial investment amounts and other details of buying, selling and exchanging shares of the Funds.

Fees and expenses are for the three months ended March 31, 2015. The fees and expenses of Columbia Acorn International Select and Columbia Acorn Select include the effect of the voluntary undertaking by Columbia Wanger Asset Management, LLC (CWAM) to reimburse each 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), after giving effect to any balance credits or overdraft charges from the Fund's custodian, do not exceed annually each class' average daily net assets as follows:

Fund	Class A			Class B			Class C			Class I			Class R4			Class R5			Class Y			Class Z
Columbia Acorn International Select		1.70	%		2.20	%		2.45	%		1.37	%		1.45	%		1.42	%		1.37	%		1.45	%
Columbia Acorn Select		1.60	%		2.10	%		2.35	%		1.22	%		1.35	%		1.27	%		1.22	%		1.35	%

These arrangements may be modified or terminated by either the Funds or CWAM on 30 days' notice.

The fees and expenses of Columbia Thermostat Fund include the effect of CWAM's contractual undertaking to waive fees and/or reimburse 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 underlying portfolio funds), do not exceed annually the rates of 0.50%, 1.00%, 1.25%, 0.25%, 0.23%, 0.18% and 0.25% of the Fund's average daily net assets attributable to Class A, Class B, Class C, Class R4, Class R5, Class Y and Class Z shares, respectively, through April 30, 2015. There is no guarantee that this agreement will continue thereafter.

The fees and expenses of Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund include the effect of CWAM's contractual undertaking to waive fees and/or reimburse expenses of each 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), of each Fund's Class A, Class C, Class I, Class R4, Class R5, Class Y (if offered) and Class Z shares through April 30, 2015, do not exceed annually each class' average daily net assets as follows:

Fund	Class A			Class C			Class I			Class R4			Class R5			Class Y			Class Z
Columbia Acorn Emerging Markets Fund		1.85	%		2.60	%		1.46	%		1.60	%		1.51	%		1.46	%		1.60	%
Columbia Acorn European Fund		1.75	%		2.50	%		1.47	%		1.50	%		1.52	%		—			1.50	%

There is no guarantee that these arrangements will continue thereafter.

The fees and expenses of Columbia Acorn International include the effect of the voluntary undertaking by CMIS to waive a portion of total annual Fund operating expenses attributable to transfer agency expenses incurred by Class A, Class B and Class C shares of Columbia Acorn International such that the Fund's 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 of the Fund, respectively.

^(a) The Funds generally no longer accept investments by new or existing investors in Class B shares, except in connection with the reinvestment of any dividend and/or capital gain distributions in Class B shares of the Funds and exchanges by existing Class B shareholders of certain other funds within the Columbia Acorn Family of Funds.

^(b) Does not include estimated fees and expenses of 0.51% incurred by the Fund from the underlying portfolio funds in which it invests.

^(c) Effective July 11, 2014, Columbia Acorn Emerging Markets Fund is closed to most new investors and new accounts, except as described in the Fund's prospectus, dated May 1, 2014, as supplemented June 12, 2014.

COLUMBIA ACORN FAMILY OF FUNDS

Trustees

Laura M. Born

Chair of the Board

Steven N. Kaplan

Vice Chair of the Board

Maureen M. Culhane

P. Zachary Egan

Margaret M. Eisen

Thomas M. Goldstein

John C. Heaton

Charles R. Phillips

David J. Rudis

Ralph Wanger (Trustee Emeritus)

Officers

P. Zachary Egan

President

Robert A. Chalupnik

Vice President

Michael G. Clarke

Assistant Treasurer

Joseph F. DiMaria

Assistant Treasurer

William J. Doyle

Vice President

David L. Frank

Vice President

Fritz Kaegi

Vice President

John M. Kunka

Treasurer and Principal Accounting and Financial Officer

Stephen Kusmierczak

Vice President

Joseph C. LaPalm

Vice President

Charles P. McQuaid

Vice President

Louis J. Mendes III

Vice President

Robert A. Mohn

Vice President

Christopher J. Olson

Vice President

Christopher O. Petersen

Assistant Secretary

Scott R. Plummer

Assistant Secretary

Robert P. Scales

Chief Compliance Officer, Chief Legal Officer,
Senior Vice President and General Counsel

Andreas Waldburg-Wolfegg

Vice President

Linda K. Roth-Wiszowaty

Secretary

Investment Manager

Columbia Wanger Asset Management, LLC
227 West Monroe Street, Suite 3000
Chicago, Illinois 60606

1-800-922-6769

Distributor

Columbia Management Investment Distributors, Inc.
225 Franklin Street
Boston, Massachusetts 02110

Transfer Agent, Dividend Disbursing Agent

Columbia Management Investment Services Corp.
P. O. Box 8081
Boston, Massachusetts 02266-8081

1-800-345-6611

Legal Counsel to the Funds

Perkins Coie LLP
Washington, DC

Legal Counsel to the Independent Trustees

Drinker Biddle & Reath LLP
Philadelphia, Pennsylvania

Independent Registered Public Accounting Firm

PricewaterhouseCoopers LLP
Chicago, Illinois

This report, including the schedules of investments, is submitted for the general information of the shareholders of Columbia Acorn Trust.

A description of the policies and procedures that the Funds use to determine how to vote proxies and a copy of the Funds' voting record are available (i) without charge, upon request, by calling 800-922-6769 and (ii) on the Securities and Exchange Commission's website at www.sec.gov. Information regarding how the Funds voted proxies relating to portfolio securities during the 12-month period ended June 30, is available from the SEC's website. Information regarding how the Funds voted proxies relating to portfolio securities is also available at columbiathreadneedle.com/us under "About Us." From there, click on "Disclosures."

The Funds file a complete schedule of portfolio holdings with the SEC for the first and third quarters of each fiscal year on Form N-Q. The Funds' Form N-Q is available on the SEC's website at www.sec.gov and may be reviewed and copied at the SEC's Public Reference Room in Washington, D.C. Information on the operation of the Public Reference Room may be obtained by calling 1-800-SEC-0330. The Funds' complete portfolio holdings are disclosed at columbiathreadneedle.com/us approximately 30 to 40 days after each month-end.

Investors should consider the investment objectives, risks, charges and expenses of a mutual fund carefully before investing. For a free prospectus and, if available, a summary prospectus, which contains this and other important information about the funds, visit columbiathreadneedle.com/us. Read the prospectus carefully before investing.

Columbia Acorn Family of Funds are distributed by Columbia Management Investment Distributors, Inc., member FINRA and managed by Columbia Wanger Asset Management, LLC.

Find out what's new – visit our website at:

columbiathreadneedle.com/us

Our e-mail address is:

serviceinquiries@columbiathreadneedle.com

Shareholders should not include personal information such as account numbers, Social Security numbers or taxpayer identification numbers in e-mail. We are unable to accept account transactions sent via e-mail.

This document contains Global Industry Classification Standard data. The Global Industry Classification Standard ("GICS") was developed by and is the exclusive property and a service mark of MSCI Inc. ("MSCI") and Standard & Poor's Financial Services LLC ("S&P") and is licensed for use by Columbia Wanger Asset Management, LLC. Neither MSCI, S&P, nor any other party involved in making or compiling the GICS or any GICS classifications makes any express or implied warranties or representations with respect to such standard or classification (or the results to be obtained by the use thereof), and all such parties hereby expressly disclaim all warranties of originality, accuracy, completeness, merchantability and fitness for a particular purpose with respect to any of such standard or classification. Without limiting any of the foregoing, in no event shall MSCI, S&P, any of their affiliates or any third party involved in making or compiling the GICS or any GICS classifications have any liability for any direct, indirect, special, punitive, consequential or any other damages (including lost profits) even if notified of the possibility of such damages.

Columbia Acorn Family of Funds
Class A, B, C, I, R, R4, R5, Y and Z Shares

First Quarter Report, March 31, 2015
225 Franklin Street, Boston, MA 02110

For More Information

You'll find more information about the Columbia Acorn Family of Funds in the documents described below. Contact Columbia Funds as follows to obtain these documents free of charge:

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 Funds' 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, Illinois 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.

Prospectuses and the Statement of Additional Information (SAI)

The prospectuses and the SAI provide more detailed information about the Funds and their policies. The SAI is legally part of each prospectus (it's incorporated by reference). A copy of each has been filed with the SEC.

Information Provided by the SEC

You can review and copy information about the Funds (including their prospectuses, the SAI and shareholder reports) at the SEC's Public Reference Room in Washington, DC. To find out more about the operation of the Public Reference Room, call the SEC at 202.551.8090. Reports and other information about the Fund are also available in the EDGAR Database on the SEC's website at http://www.sec.gov, or you can receive copies of this information, for a fee, by electronic request at the following e-mail address: publicinfo@sec.gov. You can also obtain copies of this information by writing the Public Reference Section, Securities and Exchange Commission, Washington, DC 20549-0102.

The investment company registration number of Columbia Acorn Trust, of which each of these Funds is a series, is 811-01829.

800.345.6611 columbiathreadneedle.com/us

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