N-CSR 1 f11205d1.htm COLUMBIA ACORN TRUST Columbia Acorn Trust

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
 

FORM N-CSR 

CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT COMPANIES 

Investment Company Act file number811-01829 

Columbia Acorn Trust
(Exact name of registrant as specified in charter)
 

71 S Wacker Dr. 

Suite 2500 

Chicago, IL 60606, USA

(Address of principal executive offices) (Zip code)
 

  

Ryan C. Larrenaga 

c/o Columbia Management
Investment Advisers, LLC 

290 Congress Street 

Boston, Massachusetts 02210 

  

Daniel J. Beckman 

c/o Columbia Management Investment Advisers, LLC 

290 Congress Street 

Boston, Massachusetts 02210 

  

Mary C. Moynihan 

Perkins Coie LLP 

700 13th Street, NW 

Suite 800 

Washington, DC 20005 


(Name and address of agent for service) 

Registrant's telephone number, including area code:   (312) 634-9200 

Date of fiscal year end: December 31 

Date of reporting period: December 31, 2021 

Form N-CSR is to be used by management investment companies to file reports with the Commission not later than 10 days after the transmission to stockholders of any report that is required to be transmitted to stockholders under Rule 30e-1 under the Investment Company Act of 1940 (17 CFR 270.30e-1). The Commission may use the information provided on Form N-CSR in its regulatory, disclosure review, inspection, and policymaking roles. 

A registrant is required to disclose the information specified by Form N-CSR, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-CSR unless the Form displays a currently valid Office of Management and Budget ("OMB") control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to Secretary, Securities and Exchange Commission, 100 F Street, NE, Washington, DC 20549. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507. 

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

  

Item 1. Reports to Stockholders. 


Annual Report
December 31, 2021
Columbia
Acorn® Fund
Columbia
Acorn International®
Columbia
Acorn USA®
Columbia
Acorn International SelectSM
Columbia
Thermostat FundSM
Columbia
Acorn European FundSM
 
Not Federally Insured • No Financial Institution Guarantee • May Lose Value

Table of Contents

3

5

7

9

11

13

15

17

19

21

23

25

27

30

53

57

59

66

90

112

113

114

117

122
Columbia Acorn Family of Funds   |  Annual Report 2021

Fund at a glance
Columbia Acorn® Fund
Investment objective
Columbia Acorn® Fund (the Fund) seeks long-term capital appreciation.
Portfolio management
Daniel Cole, CFA
Co-Portfolio Manager since April 2021
Service with Fund since 2021
Erika K. Maschmeyer, CFA
Co-Portfolio Manager since 2019
Service with Fund since 2016
John L. Emerson, CFA
Co-Portfolio Manager since April 2021
Service with Fund since 2003
Morningstar style boxTM
The Morningstar Style Box is based on a fund’s portfolio holdings. For equity funds, the vertical axis shows the market capitalization of the stocks owned, and the horizontal axis shows investment style (value, blend, or growth). Information shown is based on the most recent data provided by Morningstar.
© 2022 Morningstar, Inc. All rights reserved. The Morningstar information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information.
Average annual total returns (%) (for the period ended December 31, 2021)
    Inception 1 Year 5 Years 10 Years Life of Fund
Class A Excluding sales charges 10/16/00 8.79 16.00 13.35 13.97
  Including sales charges   2.57 14.64 12.68 13.84
Advisor Class 11/08/12 9.03 16.27 13.61 14.32
Class C Excluding sales charges 10/16/00 7.95 15.11 12.51 13.11
  Including sales charges   7.10 15.11 12.51 13.11
Institutional Class 06/10/70 8.99 16.26 13.64 14.33
Institutional 2 Class 11/08/12 9.09 16.30 13.67 14.34
Institutional 3 Class 11/08/12 9.16 16.37 13.73 14.35
Russell 2500 Growth Index   5.04 17.65 15.75 -
Performance numbers reflect all Fund expenses. Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class C shares are shown with and without the maximum contingent deferred sales charge of 1.00% for the first year after purchase. The Fund’s other share classes are not subject to sales charges, but may be subject to other fees and expenses, and have limited eligibility. Please see the Fund’s prospectus for details. Performance for different share classes will vary based on differences in sales charges and certain fees and expenses associated with each share class.
As stated in the May 1, 2021 prospectus, as supplemented, the Fund’s annual operating expense ratio is 0.86% for Institutional Class shares and 1.11% for Class A shares.
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 reflect the effect of fee waivers or reimbursements of Fund expenses by the investment manager and/or its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower.
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 columbiathreadneedleus.com/investor/ or calling 800.922.6769.
The returns shown for periods prior to the share class inception date (including returns for the Life of the Fund, if shown, which are since Fund inception) include the returns of 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/investor/investment-products/mutual-funds/appended-performance for more information.
The Russell 2500 Growth Index measures the performance of those Russell 2500 companies with higher price-to-book ratios and higher forecasted growth values.
Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.
The COVID-19 pandemic has adversely impacted economies and capital markets around the world in ways that will likely continue and may change in unforeseen ways for an indeterminate period. The COVID-19 pandemic may exacerbate pre-existing political, social and economic risks in certain countries and globally. Fund performance may be significantly negatively impacted by the economic impact of the COVID-19 pandemic.
Columbia Acorn Family of Funds  | Annual Report 2021
3

Fund at a glance  (continued)
Columbia Acorn® Fund
The Growth of a $10,000 Investment in Columbia Acorn® Fund Institutional Class Shares
December 31, 2011 through December 31, 2021
This chart shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period. Although the index is provided for use in assessing the Fund’s performance, the Fund’s holdings may differ significantly from those in an index. Performance numbers reflect all Fund expenses.
Portfolio breakdown (%) (at December 31, 2021)
Common Stocks 97.4
Money Market Funds 1.8
Securities Lending Collateral 0.8
Total 100.0
Percentages indicated are based upon total investments excluding investments in derivatives, if any. The Fund’s portfolio composition is subject to change.
Equity sector breakdown (%) (at December 31, 2021)
Communication Services 3.5
Consumer Discretionary 19.0
Consumer Staples 2.3
Energy 1.5
Financials 4.4
Health Care 22.1
Industrials 14.6
Information Technology 28.3
Materials 2.6
Real Estate 1.7
Total 100.0
Percentages indicated are based upon total equity investments. The Fund’s portfolio composition is subject to change.
 
4 Columbia Acorn Family of Funds  | Annual Report 2021

Manager Discussion of Fund Performance
Columbia Acorn® Fund
Columbia Acorn® Fund Institutional Class shares returned 8.99% for the 12-month period ended December 31, 2021, outperforming the 5.04% return of the Fund’s primary benchmark, the Russell 2500 Growth Index.
Market overview
U.S. equities performed very well in 2021, with most aspects of the macroeconomic environment providing a tailwind for risk assets. Although COVID-19 remained persistent due to the emergence of new variants throughout the year, the rollout of multiple vaccines enabled a gradual return toward pre-pandemic business conditions. Economic growth surged as a result, leading to favorable comparisons versus the depressed levels of 2020. Corporate earnings rose in kind, with results tracking ahead of expectations in each of the year’s four quarters. Monetary and fiscal policy was also highly supportive, fueling a steady appetite for risk among investors.
Despite these positive developments, small- and mid-cap growth stocks trailed most other segments of the U.S. equity market in 2021. After performing reasonably well through mid-November, the asset class experienced considerable underperformance in the final six weeks of the year. The U.S. Federal Reserve’s indication of its intent to begin raising short-term interest rates in 2022 factored into the downturn late in the year. The prospect of higher interest rates is typically a headwind for small- to mid-sized growth stocks since it reduces the value of their expected future earnings when measured in current dollars.
The resulting sell-off represented one of the largest pullbacks in secular growth company investments that we have witnessed in many years. Believing this created some very attractive long-term opportunities, we remained on a sharp lookout for stocks that we believe have been unjustifiably beaten down by larger trends. As always, we stayed focused on seeking to invest in growing companies with outstanding business models and competitive advantages that we believe should strengthen over time.
The Fund’s broader investment strategy was an important reason for its outperformance in 2021. Lower quality companies, particularly those without current profits, lagged considerably during the downturn late in the year. On the other hand, the types of higher quality, profitable growers we seek held up much better than the overall small- and mid-cap category. We believe this helps illustrate the merits of emphasizing bottom-up company research rather than trying to predict macroeconomic developments such as inflation or the direction of Fed policy.
This steady approach helped the Fund meet or exceed the returns of the corresponding benchmark components in seven of the ten sectors in which it held a position.
The Fund’s notable contributors during the period
Our process generated the best relative performance in the Fund’s information technology sector holdings.
Endava PLC, an IT consultant focused on helping its customers with digital transformations, was a top contributor in the sector. The company has effectively capitalized on the strong growth of its end markets, fueling an acceleration in revenues and bottom-line earnings. 
Sprout Social, Inc., a provider of social media marketing management software, benefited from the rapid shift in corporate marketing budgets toward social media.
Bill.com Holdings, Inc. offers cloud-based software that helps small and mid-size businesses automate their back office financial operations. The shares rose due to an acquisition that is expected to help the company expand its customer base.
Our investments in financials also outpaced their sector peers by a wide margin. Upstart Holdings, Inc., which operates an artificial intelligence (AI)-based lending platform primarily serving the personal and auto loan market, was the leading contributor. The shares jumped as the company grew more quickly than expected since its December 2020 initial public offering. We sold the stock on the basis of valuation prior to its downturn late in the year.
Industrials was also an area of relative strength in 2021.
Columbia Acorn Family of Funds  | Annual Report 2021
5

Manager Discussion of Fund Performance  (continued)
Columbia Acorn® Fund
Atkor, Inc., a specialized producer of electrical products used in commercial and industrial end markets, is one of only a handful of vendors that supply a very fragmented customer base. This affords Atkor with what we call “niche dominance,” one of the key features we look for in our portfolio holdings. Broader trends were also at the company’s back in 2021, highlighted by rising prices for PVC pipe and steel.
Generac Holdings, Inc., a manufacturer of power-generation equipment, was another top performer in industrials. Generac’s offerings saw rapid adoption in recent years as the strained and aging U.S. power grid reinforced the value proposition of its products.
Sector allocations, while a residual effect of our bottom-up stock selection process, nonetheless contributed to performance in the annual period. Overweight positions in the strong-performing information technology and consumer discretionary sectors were the primary source of the positive results.
The Fund’s notable detractors during the period
Consumer discretionary was one of only three sectors in which our stock picks underperformed.
Chegg, Inc., a provider of online education-related content and support, was the largest detractor in both the sector and the Fund as a whole. Its growth rate moderated more than we expected following its pandemic-assisted gains in 2020, weighing on its shares. Still, we believe the company continues to offer the world’s leading online learning platform.
Vroom, Inc., an e-commerce platform for buying and selling new and used cars, also hurt relative performance in consumer discretionary. Vroom has a leading market position in this small but fast-growing area, but its stock lagged due in part to its announcement that it was increasing its investment in infrastructure. While investors focused on the effect this move would have on near-term profits, we believe it can help the company build its brand and achieve longer term scale benefits.
Our investments in health care trailed their sector peers as well. Amedisys, Inc., a home healthcare and hospice service provider, declined as the firm saw incrementally lower average length of patient stays. The downturn occurred despite positive trends in Amedisys’ core business segments and the broader backdrop of the aging U.S. population.
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. See the Fund’s prospectus for more information on these and other risks.
The views expressed in this report reflect the current views of the respective parties. 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 parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific securities should not be construed as a recommendation or investment advice.
6 Columbia Acorn Family of Funds  | Annual Report 2021

Fund at a glance
Columbia Acorn International®
Investment objective
Columbia Acorn International® (the Fund) seeks long-term capital appreciation.
Portfolio management
Tae Han (Simon) Kim, CFA
Co-Portfolio Manager since 2017
Service with Fund since 2011
Hans F. Stege
Co-Portfolio Manager since 2020
Service with Fund since 2017
Morningstar style boxTM
The Morningstar Style Box is based on a fund’s portfolio holdings. For equity funds, the vertical axis shows the market capitalization of the stocks owned, and the horizontal axis shows investment style (value, blend, or growth). Information shown is based on the most recent data provided by Morningstar.
© 2022 Morningstar, Inc. All rights reserved. The Morningstar information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information.
Average annual total returns (%) (for the period ended December 31, 2021)
    Inception 1 Year 5 Years 10 Years Life of Fund
Class A Excluding sales charges 10/16/00 12.63 13.11 9.62 10.00
  Including sales charges   6.17 11.78 8.98 9.78
Advisor Class 11/08/12 12.88 13.39 9.88 10.37
Class C Excluding sales charges 10/16/00 11.76 12.26 8.80 9.18
  Including sales charges   10.81 12.26 8.80 9.18
Institutional Class 09/23/92 12.89 13.39 9.91 10.38
Institutional 2 Class 08/02/11 12.97 13.46 9.97 10.39
Institutional 3 Class 11/08/12 13.00 13.51 10.01 10.42
Class R 08/02/11 12.34 12.83 9.29 9.71
MSCI ACWI ex USA SMID Cap Growth Index (Net)   8.51 12.25 9.34 -
MSCI ACWI ex USA SMID Cap Index (Net)   10.16 10.30 8.63 -
Performance numbers reflect all Fund expenses. Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class C shares are shown with and without the maximum contingent deferred sales charge of 1.00% for the first year after purchase. The Fund’s other share classes are not subject to sales charges, but may be subject to other fees and expenses, and have limited eligibility. Please see the Fund’s prospectus for details. Performance for different share classes will vary based on differences in sales charges and certain fees and expenses associated with each share class.
As stated in the May 1, 2021 prospectus, as supplemented, the Fund’s annual operating expense ratio is 0.99% for Institutional Class shares and 1.24% for Class A shares.
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 reflect the effect of fee waivers or reimbursements of Fund expenses by the investment manager and/or its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower.
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 columbiathreadneedleus.com/investor/ or calling 800.922.6769.
The returns shown for periods prior to the share class inception date (including returns for the Life of the Fund, if shown, which are since Fund inception) include the returns of 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/investor/investment-products/mutual-funds/appended-performance for more information.
The MSCI ACWI ex USA SMID Cap Growth Index (Net) captures a mid- and small-cap representation across 22 developed market countries and 25 emerging market countries.
The MSCI ACWI ex USA SMID Cap Index (Net) captures a mid- and small-cap representation across 22 of 23 developed market countries (excluding the United States) and 25 emerging market countries. The index covers approximately 28% of the free float-adjusted market capitalization in each country.
Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.
The COVID-19 pandemic has adversely impacted economies and capital markets around the world in ways that will likely continue and may change in unforeseen ways for an indeterminate period. The COVID-19 pandemic may exacerbate pre-existing political, social and economic risks in certain countries and globally.  Fund performance may be significantly negatively impacted by the economic impact of the COVID-19 pandemic.
Columbia Acorn Family of Funds  | Annual Report 2021
7

Fund at a glance  (continued)
Columbia Acorn International®
The Growth of a $10,000 Investment in Columbia Acorn International® Institutional Class Shares
December 31, 2011 through December 31, 2021
This chart shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period. Although the indexes are provided for use in assessing the Fund’s performance, the Fund’s holdings may differ significantly from those in an index. Performance numbers reflect all Fund expenses.
Equity sector breakdown (%) (at December 31, 2021)
Communication Services 4.4
Consumer Discretionary 12.6
Consumer Staples 2.7
Financials 8.6
Health Care 17.2
Industrials 21.2
Information Technology 25.1
Materials 4.4
Real Estate 3.8
Total 100.0
Percentages indicated are based upon total equity investments. The Fund’s portfolio composition is subject to change.
Country breakdown (%) (at December 31, 2021)
Australia 5.3
Austria 0.6
Brazil 1.8
Canada 2.6
China 2.4
Denmark 3.6
Finland 0.8
France 0.6
Germany 7.5
Country breakdown (%) (at December 31, 2021)
Greece 0.5
Italy 4.6
Japan 16.5
Malta 0.5
Mexico 1.1
Netherlands 4.3
New Zealand 1.9
Russian Federation 1.6
Singapore 1.1
South Korea 2.4
Spain 1.9
Sweden 9.8
Switzerland 3.6
Taiwan 5.4
United Kingdom 15.2
United States(a) 4.0
Vietnam 0.4
Total 100.0
    
(a) Includes investments in Money Market Funds.
Country breakdown is based primarily on issuer’s place of organization/incorporation. Percentages indicated are based upon total investments excluding investments in derivatives, if any. The Fund’s portfolio composition is subject to change.
 
8 Columbia Acorn Family of Funds  | Annual Report 2021

Manager Discussion of Fund Performance
Columbia Acorn International®
Columbia Acorn International® Institutional Class shares returned 12.89% for the 12-month period ended December 31, 2021, outperforming the 8.51% return of the Fund’s primary benchmark, the MSCI ACWI ex USA SMID Cap Growth Index (Net). The Fund’s secondary benchmark, the MSCI ACWI ex USA SMID Cap Index (Net), ended the 12-month period with a return of 10.16%.
Market overview
International equities delivered robust total returns in 2021, as the gradual lifting of COVID-19-related restrictions led to a surge in economic growth and corporate earnings. Monetary policy was also supportive throughout the majority of the year, with central banks holding interest rates near zero and maintaining stimulative quantitative easing programs. Although concerns about new variants of the coronavirus, higher inflation, and the possibility of rising rates in 2022 weighed on sentiment at various points, most major world indexes closed the year at or near their all-time highs.
International small-cap growth stocks trailed the broader global markets in 2021. This reflected the underperformance of the foreign markets relative to the United States and the growth style compared to value. Still, the asset class continued to offer an abundance of opportunities for us to use our bottom-up approach to unearth higher quality, growing companies with pricing power, strong market positions, and capable management teams.
Since our emphasis is on individual stock selection, we don’t attempt to make macroeconomic forecasts. We believe we can add more value as managers by doing bottom-up research to identify compelling company-level ideas than we would by trying to anticipate the next market-moving headline. Moreover, we think the best way to navigate shifting market conditions is to maintain a steady focus on good companies that are executing well. The recent surge in inflation offers a prime example. We can’t predict which way inflation is going to trend in the year ahead, but we think our emphasis on companies with leading market positions and pricing power should hold the Fund in good stead across the full range of possible outcomes. Our belief that good companies can manage through any environment has been the foundation of our strategy over time. This steady approach worked well in 2021, as several of our longer term holdings delivered healthy returns on the strength of company-specific developments.
The Fund’s notable contributors during the period
Our process generated strong relative performance in Fund holdings in the consumer staples sector. The luxury consumer products company Inter Parfums, Inc. accounted for nearly all of the contribution. While the company is based in France, the stock is listed in the United States. The valuation between the U.S. and French listings narrowed, benefiting the Fund. The market also recognized the potential for significant value creation from the company’s addition of two new luxury perfume brands.
The industrials sector was another area of strength for the Fund in the annual period.
IMCD NV, a Netherlands-based distributor of specialty chemicals, gained ground on the strength of better-than-expected results, rising market share, and improved pricing power.
AddTech AB, a Swedish provider of automation and manufacturing equipment, also made a sizable contribution to the Fund’s results. A larger, similar company went public late in the year, prompting investors to assign a higher valuation to AddTech.
Our stock picks also performed very well in the health care and communication services sectors.
Eckert & Ziegler Strahlen- und Medizintechnik AG, a German producer of radioactive isotopes and associated technology for use in medical, scientific and industrial end markets, was a top performer in health care. The company’s rapidly growing radiopharma segment benefited from the rise of precision oncology radiology treatments and associated advancements in PET/CT scan imaging systems. In addition, positive news flow around the use of these targeted therapies for prostate cancer raised expectations that the company could benefit from a large increase its addressable market.
Rightmove PLC, which operates the United Kingdom’s largest online real estate portal and property website, was the leading contributor in communication services. The stock rallied on the strength of the company’s sustained pricing power, rising revenue per user, and the general upswing in the nation’s property market.
Columbia Acorn Family of Funds  | Annual Report 2021
9

Manager Discussion of Fund Performance  (continued)
Columbia Acorn International®
Sector allocations, while a residual effect of our bottom-up stock selection process, nonetheless contributed to performance in the annual period. Overweight positions in information technology and financials aided results, as did an underweight in the defensive consumer staples sector and a lack of exposure to utilities stocks.
The Fund’s notable detractors during the period
The materials sector was one of only three sectors in which our stock picks underperformed. The shortfall was largely a result of weakness in the shares of the Swiss composite engineering company Gurit Holding AG.
The Fund also lost some ground in the consumer discretionary sector. Hikari Tsushin, Inc., a sales outsourcing company operating in Japan, was the largest detractor in the sector. The stock slid as volatility in its end markets caused investors to overlook the company’s ongoing shift to a recurring revenue model. 
While the Fund’s information technology holdings lagged only slightly behind those in the benchmark, certain stocks finished among our largest detractors in 2021.
TeamViewer AG, based in Germany, was the Fund’s leading individual detractor. The stock was hurt by a management shuffle and weaker-than-expected profit margins. We became less enthusiastic on the company’s growth prospects, prompting us to sell the position.
Elecom Co., Ltd. is a Japanese producer of personal computer peripherals with an asset-light, e-commerce-driven business model. Although the firm has demonstrated prowess in development and execution, its shares experienced short-term weakness after its results came in below expectations.
SimCorp AS, a provider of investment management software solutions and services, also detracted due to slower new client signings stemming from COVID-related uncertainty. 
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. 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. See the Fund’s prospectus for more information on these and other risks.
The views expressed in this report reflect the current views of the respective parties. 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 parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific securities should not be construed as a recommendation or investment advice.
10 Columbia Acorn Family of Funds  | Annual Report 2021

Fund at a glance
Columbia Acorn USA®
Investment objective
Columbia Acorn USA® (the Fund) seeks long-term capital appreciation.
Portfolio management
Erika K. Maschmeyer, CFA
Co-Portfolio Manager since April 2021
Service with Fund since 2016
John L. Emerson, CFA
Co-Portfolio Manager since April 2021
Service with Fund since 2003
Effective May 1, 2022, Daniel Cole will be added as a Co-Portfolio Manager to the Fund.
Morningstar style boxTM
The Morningstar Style Box is based on a fund’s portfolio holdings. For equity funds, the vertical axis shows the market capitalization of the stocks owned, and the horizontal axis shows investment style (value, blend, or growth). Information shown is based on the most recent data provided by Morningstar.
© 2022 Morningstar, Inc. All rights reserved. The Morningstar information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information.
Average annual total returns (%) (for the period ended December 31, 2021)
    Inception 1 Year 5 Years 10 Years Life of Fund
Class A Excluding sales charges 10/16/00 8.74 15.46 13.96 11.00
  Including sales charges   2.48 14.11 13.29 10.74
Advisor Class 11/08/12 8.92 15.75 14.25 11.34
Class C Excluding sales charges 10/16/00 7.85 14.59 13.14 10.18
  Including sales charges   7.02 14.59 13.14 10.18
Institutional Class 09/04/96 8.95 15.74 14.24 11.34
Institutional 2 Class 11/08/12 8.99 15.83 14.33 11.37
Institutional 3 Class 11/08/12 9.09 15.88 14.38 11.39
Russell 2000 Growth Index   2.83 14.53 14.14 -
Performance numbers reflect all Fund expenses. Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class C shares are shown with and without the maximum contingent deferred sales charge of 1.00% for the first year after purchase. The Fund’s other share classes are not subject to sales charges, but may be subject to other fees and expenses, and have limited eligibility. Please see the Fund’s prospectus for details. Performance for different share classes will vary based on differences in sales charges and certain fees and expenses associated with each share class.
As stated in the May 1, 2021 prospectus, as supplemented, the Fund’s annual operating expense ratio is 1.15% for Institutional Class shares and 1.40% for Class A shares.
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 reflect the effect of fee waivers or reimbursements of Fund expenses by the investment manager and/or its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower.
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 columbiathreadneedleus.com/investor/ or calling 800.922.6769.
The returns shown for periods prior to the share class inception date (including returns for the Life of the Fund, if shown, which are since Fund inception) include the returns of 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/investor/investment-products/mutual-funds/appended-performance for more information.
The Russell 2000 Growth Index, an unmanaged index, measures the performance of those Russell 2000 Index companies with higher price-to-book ratios and higher forecasted growth values.
Effective May 1, 2022, the Fund will compare its performance to that of the Russell 2500 Growth Index. The Fund’s investment manager believes that the new index provides a more appropriate comparison than the Russell 2000 Growth Index for investors measuring the Fund’s relative performance. The Russell 2500 Growth Index measures the performance of those Russell 2500 companies with higher price-to-book ratios and higher forecasted growth values. Information on both the Russell 2000 Growth Index and the Russell 2500 Growth Index will be shown for a one-year transition period.
Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.
The COVID-19 pandemic has adversely impacted economies and capital markets around the world in ways that will likely continue and may change in unforeseen ways for an indeterminate period. The COVID-19 pandemic may exacerbate pre-existing political, social and economic risks in certain countries and globally.  Fund performance may be significantly negatively impacted by the economic impact of the COVID-19 pandemic.
Columbia Acorn Family of Funds  | Annual Report 2021
11

Fund at a glance  (continued)
Columbia Acorn USA®
The Growth of a $10,000 Investment in Columbia Acorn USA® Institutional Class Shares
December 31, 2011 through December 31, 2021
This chart shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period. Although the index is provided for use in assessing the Fund’s performance, the Fund’s holdings may differ significantly from those in an index. Performance numbers reflect all Fund expenses.
Portfolio breakdown (%) (at December 31, 2021)
Common Stocks 93.9
Limited Partnerships 1.5
Money Market Funds 2.9
Securities Lending Collateral 1.6
Warrants 0.1
Total 100.0
Percentages indicated are based upon total investments excluding investments in derivatives, if any. The Fund’s portfolio composition is subject to change.
Equity sector breakdown (%) (at December 31, 2021)
Communication Services 1.5
Consumer Discretionary 22.3
Consumer Staples 3.3
Energy 1.1
Financials 6.4
Health Care 26.5
Industrials 16.5
Information Technology 18.2
Materials 1.6
Real Estate 2.6
Total 100.0
Percentages indicated are based upon total equity investments. The Fund’s portfolio composition is subject to change.
 
12 Columbia Acorn Family of Funds  | Annual Report 2021

Manager Discussion of Fund Performance
Columbia Acorn USA®
Columbia Acorn USA® Institutional Class shares returned 8.95% for the 12-month period ended December 31, 2021, outperforming the 2.83% return of the Fund’s primary benchmark, the Russell 2000 Growth Index.
Market overview
U.S. equities performed very well in 2021, with most aspects of the macroeconomic environment providing a tailwind for risk assets. Although COVID-19 remained persistent due to the emergence of new variants throughout the year, the rollout of multiple vaccines enabled a gradual return toward pre-pandemic business conditions. Economic growth surged as a result, leading to favorable comparisons versus the depressed levels of 2020. Corporate earnings rose in kind, with results tracking ahead of expectations in each of the year’s four quarters. Monetary and fiscal policy was also highly supportive, fueling a steady appetite for risk among investors.
Despite these positive developments, small-cap growth stocks trailed most other segments of the U.S. equity market in 2021. After performing reasonably well through mid-November, the asset class experienced considerable underperformance in the final six weeks of the year. The U.S. Federal Reserve’s indication of its intent to begin raising short-term interest rates in 2022 factored into the downturn late in the year. The prospect of higher rates is typically a headwind for smaller growth stocks since it reduces the value of their expected future earnings when measured in current dollars.
The resulting sell-off represented one of the largest pullbacks in secular growth company investments that we have witnessed in many years. Believing this created some very attractive long-term opportunities, we remained on a sharp lookout for stocks that we believe have been unjustifiably beaten down by larger trends. As always, we stayed focused on seeking to invest in growing companies with outstanding business models and competitive advantages that we believe will strengthen over time.
The Fund’s broader investment strategy was an important reason for its outperformance in 2021. Lower quality companies, particularly those without current profits, lagged considerably during the downturn late in the year. On the other hand, the types of higher quality, profitable growers we seek held up much better than the overall small- and mid-cap category. We believe this helps illustrate the merits of emphasizing bottom-up company research rather than trying to predict macroeconomic developments such as inflation or the direction of Fed policy.
This steady approach helped the Fund meet or exceed the returns of the corresponding benchmark components in seven of the nine sectors in which it held a position.
The Fund’s notable contributors during the period
Our process generated strong relative performance in Fund holdings in the industrials sector.
Atkor, Inc., a specialized producer of electrical products used in commercial and industrial end markets, is one of only a handful of vendors that supply a very fragmented customer base. This affords Atkor with what we call “niche dominance,” one of the key features we look for in our portfolio holdings. Broader trends were also at the company’s back in 2021, highlighted by rising prices for PVC pipe and steel.
SiteOne Landscape Supply, Inc. further contributed to results. The company benefited from its position as a distributor situated between a fragmented group of suppliers (equipment makers) and an equally fragmented customer base (landscapers). The company has both scale power and an excellent management team, and these traits fed through to performance.
The health care and consumer discretionary sectors were also areas in which our stock picks outperformed in 2021.
Upstart Holdings, Inc., a financial stock, was the leading individual contributor for the year. The company operates an artificial intelligence (AI)-based lending platform primarily serving the personal and auto loan market. The shares jumped as the company grew more quickly than expected since its December 2020 initial public offering. We sold the stock on the basis of valuation prior to its downturn late in the year.
Sprout Social, Inc., a provider of social media marketing management software that has benefited from the rapid shift in corporate marketing budgets toward to social media, was another top contributor in 2021.
Columbia Acorn Family of Funds  | Annual Report 2021
13

Manager Discussion of Fund Performance  (continued)
Columbia Acorn USA®
Sector allocations, while a residual effect of our bottom-up stock selection process, nonetheless contributed to performance. An overweight position in the industrials sector aided results, as did a zero weighting in the poor-performing communication services sector.
The Fund’s notable detractors during the period
Information technology, while home to a number of our top contributors, was a sector in which the Fund underperformed by a meaningful margin. Voyager Digital Ltd., an operator of a cryptocurrency trading app, and Olo, Inc., a software-as-a-service provider for restaurants, were two significant detractors.
Poshmark, Inc., an operator of an online marketplace for resellers of apparel and accessories, was the Fund’s largest individual detractor in 2021. The company’s initial results and conservative guidance weighed on the shares, as did the overall weakness in recent initial public offerings during the second half of the year. Nevertheless, we believe Poshmark possesses a compelling platform that effectively blends valuable aspects of social media with e-commerce to create a collaborative, highly engaged and growing network of buyers and sellers.
Vroom, Inc., an e-commerce platform for buying and selling new and used cars, was another notable detractor in consumer discretionary. Vroom has a leading market position in this small but fast-growing area, but its stock lagged due in part to its announcement that it was increasing its investment in infrastructure. While investors focused on the effect this move would have on near-term profits, we believe it can help the company build its brand and achieve longer term scale benefits.
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 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. See the Fund’s prospectus for more information on these and other risks.
The views expressed in this report reflect the current views of the respective parties. 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 parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific securities should not be construed as a recommendation or investment advice.
14 Columbia Acorn Family of Funds  | Annual Report 2021

Fund at a glance
Columbia Acorn International SelectSM
Investment objective
Columbia Acorn International SelectSM (the Fund) seeks long-term capital appreciation.
Portfolio management
Stephen Kusmierczak, CFA
Lead Portfolio Manager or Co-Portfolio Manager since 2016
Service with Fund since 2001
Hans F. Stege
Co-Portfolio Manager since 2019
Service with Fund since 2017
Morningstar style boxTM
The Morningstar Style Box is based on a fund’s portfolio holdings. For equity funds, the vertical axis shows the market capitalization of the stocks owned, and the horizontal axis shows investment style (value, blend, or growth). Information shown is based on the most recent data provided by Morningstar.
© 2022 Morningstar, Inc. All rights reserved. The Morningstar information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information.
Average annual total returns (%) (for the period ended December 31, 2021)
    Inception 1 Year 5 Years 10 Years Life of Fund
Class A Excluding sales charges 10/16/00 10.49 15.59 10.31 9.16
  Including sales charges   4.15 14.23 9.66 8.88
Advisor Class 11/08/12 10.78 15.89 10.60 9.49
Class C Excluding sales charges 10/16/00 9.68 14.73 9.47 8.34
  Including sales charges   8.68 14.73 9.47 8.34
Institutional Class 11/23/98 10.79 15.88 10.61 9.49
Institutional 2 Class 11/08/12 10.87 15.98 10.67 9.52
Institutional 3 Class 11/08/12 10.93 16.04 10.72 9.54
MSCI ACWI ex USA Growth Index (Net)   5.09 13.06 9.13 -
MSCI ACWI ex USA Index (Net)   7.82 9.61 7.28 -
Performance numbers reflect all Fund expenses. Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class C shares are shown with and without the maximum contingent deferred sales charge of 1.00% for the first year after purchase. The Fund’s other share classes are not subject to sales charges, but may be subject to other fees and expenses, and have limited eligibility. Please see the Fund’s prospectus for details. Performance for different share classes will vary based on differences in sales charges and certain fees and expenses associated with each share class.
As stated in the May 1, 2021 prospectus, as supplemented, the Fund’s annual operating expense ratio is 0.99% for Institutional Class shares and 1.24% for Class A shares.
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 reflect the effect of fee waivers or reimbursements of Fund expenses by the investment manager and/or its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower.
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 columbiathreadneedleus.com/investor/ or calling 800.922.6769.
The returns shown for periods prior to the share class inception date (including returns for the Life of the Fund, if shown, which are since Fund inception) include the returns of 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/investor/investment-products/mutual-funds/appended-performance for more information.
The MSCI ACWI ex USA Growth Index (Net) captures a large- and mid-cap representation across 22 developed market countries and 25 emerging market countries.
The MSCI ACWI ex USA Index (Net) captures a large- and mid-cap representation across 22 of 23 developed market countries (excluding the United States) and 25 emerging market countries. The index covers approximately 85% of the global equity opportunity set outside 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.
The COVID-19 pandemic has adversely impacted economies and capital markets around the world in ways that will likely continue and may change in unforeseen ways for an indeterminate period. The COVID-19 pandemic may exacerbate pre-existing political, social and economic risks in certain countries and globally.  Fund performance may be significantly negatively impacted by the economic impact of the COVID-19 pandemic.
Columbia Acorn Family of Funds  | Annual Report 2021
15

Fund at a glance  (continued)
Columbia Acorn International SelectSM
The Growth of a $10,000 Investment in Columbia Acorn International SelectSM Institutional Class Shares
December 31, 2011 through December 31, 2021
This chart shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period. Although the indexes are provided for use in assessing the Fund’s performance, the Fund’s holdings may differ significantly from those in an index. Performance numbers reflect all Fund expenses.
Equity sector breakdown (%) (at December 31, 2021)
Communication Services 6.0
Consumer Discretionary 9.7
Financials 7.8
Health Care 20.7
Industrials 28.8
Information Technology 23.2
Materials 1.8
Real Estate 2.0
Total 100.0
Percentages indicated are based upon total equity investments. The Fund’s portfolio composition is subject to change.
Country breakdown (%) (at December 31, 2021)
Australia 2.1
Brazil 2.1
Canada 1.8
China 4.9
Denmark 3.0
Finland 2.2
Germany 4.2
Italy 4.8
Japan 13.5
Malta 0.0(a)
Netherlands 6.5
New Zealand 3.4
Singapore 2.0
South Korea 1.6
Sweden 11.5
Switzerland 11.6
Taiwan 7.3
United Kingdom 16.6
United States(b) 0.9
Total 100.0
    
(a) Rounds to zero.
(b) Includes investments in Money Market Funds.
Country breakdown is based primarily on issuer’s place of organization/incorporation. Percentages indicated are based upon total investments excluding investments in derivatives, if any. The Fund’s portfolio composition is subject to change.
 
16 Columbia Acorn Family of Funds  | Annual Report 2021

Manager Discussion of Fund Performance
Columbia Acorn International SelectSM
Columbia Acorn International SelectSM Institutional Class shares returned 10.79% for the 12-month period ended December 31, 2021, outperforming the 5.09% return of the Fund’s primary benchmark, the MSCI ACWI ex USA Growth Index (Net). The Fund’s secondary benchmark, the MSCI ACWI ex USA Index (Net), ended the 12-month period with a return of 7.82%.
Market overview
International equities delivered robust total returns in 2021, as the gradual lifting of virus-related restrictions led to a surge in economic growth and corporate earnings. Monetary policy was also supportive throughout the majority of the year, with central banks holding interest rates near zero and maintaining stimulative quantitative easing programs. Although concerns about new variants of the coronavirus, higher inflation, and the possibility of rising rates in 2022 weighed on sentiment at various points, most major world indexes closed the year at or near their all-time highs.
International small-cap growth stocks trailed the broader global markets in 2021. This reflected the underperformance of the foreign markets relative to the United States and the growth style compared to value. Still, the asset class continued to offer an abundance of opportunities for us to use our bottom-up approach to unearth higher quality, growing companies with pricing power, strong market positions, and capable management teams.
Since our emphasis is on individual stock selection, we don’t attempt to make macroeconomic forecasts. We believe we can add more value as managers by doing bottom-up research to identify compelling company-level ideas than we would by trying to anticipate the next market-moving headline. Moreover, we think the best way to navigate shifting market conditions is to maintain a steady focus on good companies that are executing well. The recent surge in inflation offers a prime example. We can’t predict which way inflation is going to trend in the year ahead, but we think our emphasis on companies with leading market positions and pricing power should hold the Fund in good stead across the full range of possible outcomes. Our belief that good companies can manage through any environment has been the foundation of our strategy over time. This steady approach worked well in 2021, as several of our longer term holdings delivered healthy returns on the strength of company-specific developments.
The Fund’s notable contributors during the period
Our process generated strong relative performance in Fund holdings in the communication services sector.
Rightmove PLC, which operates the United Kingdom’s largest online real estate portal and property website, was the leading contributor in communication services. The stock rallied on the strength of the company’s sustained pricing power, rising revenue per user, and the general upswing in the nation’s property market.
The industrials sector was a further area of strength for the Fund in the annual period.
IMCD NV, a Netherlands-based distributor of specialty chemicals, gained ground on the strength of better-than-expected results. The company’s introduction of new products, together with its successful pricing increases, helped it generate higher profit margins.
Belimo Holding AG, based in Switzerland, was also a top contributor in industrials. The company, which makes actuators and valves for HVAC systems, benefited from trends such as rising infrastructure spending, urbanization, and the shift toward energy efficiency.
Our stock picks also performed very well in health care and financials.
Dechra Pharmaceuticals PLC, a U.K.-based provider of pharmaceuticals and related health care products for animals, was a top contributor in the health care sector. The company continued to leverage a strong and diverse product portfolio to drive robust results.
Partners Group Holding AG was the leading contributor in financials. One of Europe’s largest private equity companies, Partners benefited from a very healthy environment for initial public offerings. Fundraising and investment levels were also quite strong, pointing to healthy fundamentals for the company.
The technology sector was home to two of the Fund’s top performing stocks for the year.
Columbia Acorn Family of Funds  | Annual Report 2021
17

Manager Discussion of Fund Performance  (continued)
Columbia Acorn International SelectSM
Shares of Nemetschek SE, a provider of building information modeling software that helps architects and builders improve efficiency and reduce costs, rallied on the strength of rising earnings and improving guidance. In addition, the broader construction software segment experienced valuation expansion amid growing investor interest in this area.
Parade Technologies Ltd., a Taiwanese semiconductor equipment company whose products enable higher speed connections between the chips on the motherboards in personal computers (PCs), also contributed. Parade was well positioned to capitalize on both the robust semiconductor cycle and better-than-expected global PC sales.
Sector allocations, while a residual effect of our bottom-up stock selection process, nonetheless contributed to performance in the annual period. Overweight positions in information technology, industrials, and health care aided results, as did an underweight in the consumer discretionary sector.
The Fund’s notable detractors during the period
Consumer discretionary was one area in which our stock picks underperformed to a meaningful degree.
New Oriental Education & Technology Group, Inc. was the largest detractor in both the sector and the Fund as a whole. The stock lagged in the first half of the year due to a significant increase in regulatory uncertainty, and we exited the position. Shortly after we sold the stock, China’s government announced a rule change that forced private tutoring companies to become non-profit entities. The stock plunged in response, so our decision to sell helped protect the Fund from additional downside.
Hikari Tsushin, Inc., a sales outsourcing company operating in Japan, was another notable detractor in consumer discretionary. The stock slid as volatility in its end markets caused investors to overlook the company’s ongoing shift to a recurring revenue model. 
While the Fund’s holdings in information technology as a whole only slightly underperformed those in the benchmark, several stocks finished among our largest detractors in 2021.
TeamViewer AG, based in Germany, lagged due to a management shuffle and weaker-than-expected profit margins. We became less enthusiastic on the company’s growth prospects, prompting us to sell the stock from the portfolio.
SimCorp AS, a provider of investment management software solutions and services, also detracted due to slower new client signings stemming from COVID-related uncertainty. 
Nexi SpA, an Italy-based payments-system provider and credit card payment processor, declined after a competitor reduced its guidance. We maintained the position on the basis of the company’s long-term growth potential.
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. See the Fund’s prospectus for more information on these and other risks.
The views expressed in this report reflect the current views of the respective parties. 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 parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific securities should not be construed as a recommendation or investment advice.
18 Columbia Acorn Family of Funds  | Annual Report 2021

Fund at a glance
Columbia Thermostat FundSM
Investment objective
Columbia Thermostat FundSM (the Fund) seeks long-term capital appreciation.
Portfolio management
Anwiti Bahuguna, Ph.D.
Co-Portfolio Manager since 2018
Service with Fund since 2018
Joshua Kutin, CFA
Co-Portfolio Manager since 2018
Service with Fund since 2018
Average annual total returns (%) (for the period ended December 31, 2021)
    Inception 1 Year 5 Years 10 Years Life of Fund
Class A Excluding sales charges 03/03/03 6.16 10.63 8.47 7.88
  Including sales charges   0.04 9.33 7.83 7.55
Advisor Class 11/08/12 6.43 10.91 8.74 8.15
Class C Excluding sales charges 03/03/03 5.40 9.81 7.66 7.08
  Including sales charges   4.47 9.81 7.66 7.08
Institutional Class 09/25/02 6.42 10.91 8.75 8.15
Institutional 2 Class 11/08/12 6.53 10.95 8.78 8.17
Institutional 3 Class 11/08/12 6.52 11.00 8.82 8.19
Blended Benchmark   12.80 11.12 9.78 -
S&P 500® Index   28.71 18.47 16.55 -
Bloomberg U.S. Aggregate Bond Index   -1.54 3.57 2.90 -
Performance numbers reflect all Fund expenses. Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class C shares are shown with and without the maximum contingent deferred sales charge of 1.00% for the first year after purchase. The Fund’s other share classes are not subject to sales charges, but may be subject to other fees and expenses, and have limited eligibility. Please see the Fund’s prospectus for details. Performance for different share classes will vary based on differences in sales charges and certain fees and expenses associated with each share class.
As stated in the May 1, 2021 prospectus, as supplemented, the Fund’s annual operating expense ratio is 0.65% for Institutional Class shares and 0.90% for Class A shares.
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 reflect the effect of fee waivers or reimbursements of Fund expenses by the investment manager and/or its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower.
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 columbiathreadneedleus.com/investor/ or calling 800.922.6769.
The returns shown for periods prior to the share class inception date (including returns for the Life of the Fund, if shown, which are since Fund inception) include the returns of 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/investor/investment-products/mutual-funds/appended-performance for more information.
The Fund’s performance prior to May 1, 2018 reflects returns achieved following a principal investment strategy pursuant to which day-to-day investment decisions for the Fund were made according to only one potential form of predetermined asset allocation table.  Since May 1, 2018, the Fund has followed a principal investment strategy that calls for the Investment Manager, on at least an annual basis, to determine whether the Fund’s assets should be allocated according to one of two different forms of allocation table based on the Investment Manager’s assessment of the equity market.  From the Fund’s inception through April 2020, the asset allocation table in place reflected the Investment Manager’s determination that the equity market was “expensive”. For a one-year period from May 1, 2020 through April 30, 2021, the Fund switched to the "normal" equity market table with a 50% equity floor because the Fund’s portfolio managers determined the market to be "normal." On May 1, 2021, the Fund moved back to the asset allocation table that was in place from the Fund’s inception in 2002 through April 30, 2020 based on the portfolio managers’ determination that the equity market is currently "expensive."
The Blended Benchmark, established by the Fund’s investment manager, is an equally weighted custom composite of the Fund’s primary equity and primary debt benchmarks, the S&P 500® Index and the Bloomberg 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 Blended Benchmark.
The S&P 500® Index tracks the performance of 500 widely held, large-capitalization U.S. stocks.
Columbia Acorn Family of Funds  | Annual Report 2021
19

Fund at a glance  (continued)
Columbia Thermostat FundSM
The Bloomberg 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. Effective August 24, 2021, the Bloomberg Barclays U.S. Aggregate Bond Index was re-branded as the Bloomberg U.S. Aggregate Bond Index.
Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.
The COVID-19 pandemic has adversely impacted economies and capital markets around the world in ways that will likely continue and may change in unforeseen ways for an indeterminate period. The COVID-19 pandemic may exacerbate pre-existing political, social and economic risks in certain countries and globally.  Fund performance may be significantly negatively impacted by the economic impact of the COVID-19 pandemic.
The Growth of a $10,000 Investment in Columbia Thermostat FundSM Institutional Class Shares
December 31, 2011 through December 31, 2021
This chart shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period. Although the indexes are provided for use in assessing the Fund’s performance, the Fund’s holdings may differ significantly from those in an index. Performance numbers reflect all Fund expenses.
Portfolio breakdown (%) (at December 31, 2021)
Equity Funds 9.1
Exchange-Traded Equity Funds 0.8
Exchange-Traded Fixed Income Funds 9.0
Fixed Income Funds 80.9
Money Market Funds 0.2
Total 100.0
Percentages indicated are based upon total investments excluding investments in derivatives, if any. The Fund’s portfolio composition is subject to change.
20 Columbia Acorn Family of Funds  | Annual Report 2021

Manager Discussion of Fund Performance
Columbia Thermostat FundSM
Columbia Thermostat FundSM Institutional Class shares returned 6.42% for the 12-month period ended December 31, 2021.  During the same time period, the Fund’s primary equity benchmark, the S&P 500® Index, returned 28.71%, and the Fund’s primary debt benchmark, the Bloomberg U.S. Aggregate Bond Index, returned -1.54%. The Fund underperformed its custom Blended Benchmark, which returned 12.80% during 2021. The Fund’s performance in 2021 was driven by a higher allocation to bonds during a period in which equities performed well.
Market overview
U.S. equities displayed remarkable resilience during the year, finishing with a solid gain despite a number of potential headwinds. Investors had to contend with the emergence of the omicron variant of COVID-19, which was contagious enough to raise concerns that a new wave of lockdowns could be necessary. The markets also faced a major shift in U.S. Federal Reserve (Fed) policy. Whereas the Fed had previously viewed rising inflation as a transitory development, continued price pressures caused the central bank to announce the tapering of its stimulative quantitative easing program. In addition, it began to prepare the financial markets for the likelihood of multiple interest rate increases in 2022. The failure of the Build Back Better bill removed a source of anticipated fiscal stimulus. Nevertheless, most major U.S. equity indices closed the year at or near their all-time highs on the strength of robust investment inflows and the lack of compelling total return potential in bonds.
As pandemic-related restrictions were eased over the period, robust economic growth and corporate earnings supported risk sentiment and credit-oriented segments of the bond market. The Fed maintained its benchmark overnight lending rate near zero while engaging in bond market purchases to keep longer term borrowing costs low. The fourth quarter of 2021 saw the Fed adopt a more hawkish tone in response to persistently high inflation, leading to increased market volatility. The Fed officially tightened policy in November as it began tapering its monthly bond purchases. December saw the Fed signal the likelihood of three increases in the federal funds rate in 2022. Bond market returns for the 12 months were muted given the move higher in U.S. Treasury yields. To illustrate, the 10-year Treasury note yield, which entered the year at 0.93%, reached as high as 1.74% at the end of the first quarter before drifting lower and ending 2021 at 1.52%. The best performing credit sector for the annual period was high-yield corporate bonds. The weakest performing credit sector was emerging markets debt.
Contributors and detractors
The Fund’s equity portfolio had a weighted average return of 23.5% in 2021. Six of seven underlying equity funds posted positive returns for the period. Columbia Research Enhanced Core ETF was the equity portfolio’s top performer, returning 33.1% for the year. Columbia Emerging Markets Fund was the equity portfolio’s worst performer, with a return of -7.2% for the year.
The Fund’s bond portfolio ended the year with a weighted average gain of -0.8%. Of the six underlying funds in the bond portfolio, Columbia Short Term Bond Fund was the strongest performer, returning 0.9% for the year. Columbia U.S. Treasury Index Fund was the worst performer in the bond portfolio, returning -2.6% for the year.
Portfolio reallocations
The Fund’s allocation table is updated annually. On May 1, 2021, based on the S&P 500® Index’s cyclically adjusted price-to-earnings ratio, the Fund rebalanced its allocation table and moved back from what the Fund defines as a normal market to what the Fund defines as an expensive market table. The expensive market allocation table utilizes stock allocations ranging from 10%-90% and will be in effect through at least April 30, 2022. On May 3, 2021 (due to May 1 falling on a Saturday), the Fund traded to a new allocation of 10% equity and 90% fixed income, from its allocation (prior to May 3, 2021) of 50% equity and 50% fixed income.
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 ininvestments 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
Columbia Acorn Family of Funds  | Annual Report 2021
21

Manager Discussion of Fund Performance  (continued)
Columbia Thermostat FundSM
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. See the Fund’s prospectus for more information on these and other risks.
The views expressed in this report reflect the current views of the respective parties. 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 parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific securities should not be construed as a recommendation or investment advice.
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 reserve capital or lower total return. The Investment Manager may select an underlying fund in the Columbia Acorn Family of Funds or broader Columbia Funds complex 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.
22 Columbia Acorn Family of Funds  | Annual Report 2021

Fund at a glance
Columbia Acorn European FundSM
Investment objective
Columbia Acorn European FundSM (the Fund) seeks long-term capital appreciation.
Portfolio management
Stephen Kusmierczak, CFA
Portfolio Manager or Co-Portfolio Manager since 2011
Service with Fund since 2011
Sebastien Pigeon, CFA
Co-Portfolio Manager since May 2021
Service with Fund since 2015
Morningstar style boxTM
The Morningstar Style Box is based on a fund’s portfolio holdings. For equity funds, the vertical axis shows the market capitalization of the stocks owned, and the horizontal axis shows investment style (value, blend, or growth). Information shown is based on the most recent data provided by Morningstar.
© 2022 Morningstar, Inc. All rights reserved. The Morningstar information contained herein: (1) is proprietary to Morningstar and/or its content providers; (2) may not be copied or distributed; and (3) is not warranted to be accurate, complete or timely. Neither Morningstar nor its content providers are responsible for any damages or losses arising from any use of this information.
Average annual total returns (%) (for the period ended December 31, 2021)
    Inception 1 Year 5 Years 10 Years Life of Fund
Class A Excluding sales charges 08/19/11 21.47 19.52 14.26 13.16
  Including sales charges   14.47 18.11 13.58 12.51
Advisor Class 06/25/14 21.75 19.83 14.55 13.45
Class C Excluding sales charges 08/19/11 20.57 18.64 13.40 12.32
  Including sales charges   19.57 18.64 13.40 12.32
Institutional Class 08/19/11 21.76 19.83 14.54 13.45
Institutional 2 Class 11/08/12 21.80 19.90 14.58 13.49
Institutional 3 Class 03/01/17 21.83 19.93 14.58 13.49
MSCI AC Europe Small Cap Index (Net)   14.74 12.84 12.67 -
Performance numbers reflect all Fund expenses. Returns for Class A shares are shown with and without the maximum initial sales charge of 5.75%. Returns for Class C shares are shown with and without the maximum contingent deferred sales charge of 1.00% for the first year after purchase. The Fund’s other share classes are not subject to sales charges, but may be subject to other fees and expenses, and have limited eligibility. Please see the Fund’s prospectus for details. Performance for different share classes will vary based on differences in sales charges and certain fees and expenses associated with each share class.
As stated in the May 1, 2021 prospectus, as supplemented, the Fund’s annual operating expense ratio is 1.20% for Institutional Class shares and 1.45% for Class A shares.
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 reflect the effect of fee waivers or reimbursements of Fund expenses by the investment manager and/or its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower.
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 columbiathreadneedleus.com/investor/ or calling 800.922.6769.
The returns shown for periods prior to the share class inception date (including returns for the Life of the Fund, if shown, which are since Fund inception) include the returns of 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/investor/investment-products/mutual-funds/appended-performance for more information.
The MSCI AC Europe Small Cap Index (Net) captures a small-cap representation across 21 markets in Europe. The index covers approximately 14% of the free float-adjusted market capitalization across each market country in Europe.
Unlike mutual funds, indexes are not managed and do not incur fees or expenses. It is not possible to invest directly in an index.
The COVID-19 pandemic has adversely impacted economies and capital markets around the world in ways that will likely continue and may change in unforeseen ways for an indeterminate period. The COVID-19 pandemic may exacerbate pre-existing political, social and economic risks in certain countries and globally. Fund performance may be significantly negatively impacted by the economic impact of the COVID-19 pandemic.
Columbia Acorn Family of Funds  | Annual Report 2021
23

Fund at a glance  (continued)
Columbia Acorn European FundSM
The Growth of a $10,000 Investment in Columbia Acorn European FundSM Institutional Class Shares
December 31, 2011 through December 31, 2021
This chart shows the change in value of a hypothetical $10,000 investment in Institutional Class shares of the Fund during the stated time period. Although the index is provided for use in assessing the Fund’s performance, the Fund’s holdings may differ significantly from those in an index. Performance numbers reflect all Fund expenses.
Equity sector breakdown (%) (at December 31, 2021)
Communication Services 5.7
Consumer Discretionary 5.3
Consumer Staples 4.7
Financials 8.7
Health Care 19.0
Industrials 29.7
Information Technology 21.7
Materials 3.0
Real Estate 2.2
Total 100.0
Percentages indicated are based upon total equity investments. The Fund’s portfolio composition is subject to change.
Country breakdown (%) (at December 31, 2021)
Austria 1.0
Cyprus 0.8
Denmark 5.1
Finland 1.8
France 1.3
Germany 12.8
Greece 0.9
Italy 9.1
Malta 1.1
Netherlands 5.5
Spain 2.8
Sweden 17.5
Switzerland 8.3
United Kingdom 27.1
United States(a) 4.9
Total 100.0
    
(a) Includes investments in Money Market Funds.
Country breakdown is based primarily on issuer’s place of organization/incorporation. Percentages indicated are based upon total investments excluding investments in derivatives, if any. The Fund’s portfolio composition is subject to change.
 
24 Columbia Acorn Family of Funds  | Annual Report 2021

Manager Discussion of Fund Performance
Columbia Acorn European FundSM
Columbia Acorn European FundSM Institutional Class shares returned 21.76% for the 12-month period ended December 31, 2021, outperforming the 14.74% return of the Fund’s primary benchmark, the MSCI AC Europe Small Cap Index (Net).
Market overview
European small-cap stocks delivered robust total returns in 2021, as the gradual lifting of virus-related restrictions led to a surge in economic growth and corporate earnings. Monetary policy was also supportive throughout the majority of the year, with central banks holding interest rates near zero and maintaining stimulative quantitative easing programs. Together, these factors outweighed worries about new variants of the coronavirus, higher inflation, and the possibility of rising rates in 2022. European stocks outperformed the broader developed-market international category for the year, as the region was less exposed to the concerns about China that pressured performance across Asia.
We believe emphasizing bottom-up company research — rather than trying to navigate ever-changing headlines and shifts among the market’s style and sector preferences — remains the key to longer term performance. Our long tenure as managers has taught us that the European markets will be subject to frequent external disruptions. We therefore don’t attempt to predict macroeconomic events. Instead, we focus on identifying great franchises through analysis of sector competitive dynamics, due diligence of management teams, a focus on companies’ competitive advantages, and a thorough analysis of valuations. This approach has been the foundation of our strategy and a key factor in the Fund’s outperformance both in 2021 and on a longer term basis.
The Fund’s notable contributors during the period
Our process generated the best relative performance in Fund holdings in the industrials sector during the annual period.
AddTech AB, a Swedish provider of automation and manufacturing equipment, made a sizable contribution to the Fund’s results. A larger, similar firm went public late in the year, prompting investors to assign a higher valuation to AddTech.
IMCD NV, a Netherlands-based distributor of specialty chemicals, gained ground on the strength of better-than-expected results, rising market share, and improved pricing power.
The Fund outperformed the benchmark in the consumer staples sector, where the luxury consumer products company Inter Parfums, Inc.accounted for nearly all of the contribution. While the company is based in France, the stock is listed in the United States. The valuation between the U.S. and French listings narrowed, benefiting the Fund. The market also recognized the potential for significant value creation from the company’s addition of two new luxury perfume brands.
Our stock picks also performed very well in the health care sector.
 Eckert & Ziegler Strahlen- und Medizintechnik AG, a German producer of radioactive isotopes and associated technology for use in medical, scientific and industrial end markets, was a top performer in the sector. The company’s rapidly growing radiopharma segment benefited from the rise of precision oncology radiology treatments and associated advancements in PET/CT scan imaging systems. In addition, positive news flow around the use of these targeted therapies in prostate cancer raised expectations that the company could benefit from a large increase its addressable market.
Dechra Pharmaceuticals PLC  is a U.K.-based provider of pharmaceuticals and related health care products for animals, with a primary focus on companion animals. The company continued to leverage a strong and diverse product portfolio to drive robust results.
The technology sector was home to one of the Fund’s top performing stocks for the year. Shares of Nemetschek SE, a provider of building information modeling software that helps architects and builders improve efficiency and reduce costs, rallied on the strength of rising earnings and improving guidance. In addition, the broader construction software segment experienced valuation expansion amid growing investor interest in this area.
Sector allocations, while a residual effect of our bottom-up stock selection process, nonetheless contributed to performance in the annual period. An overweight in the industrials sector, where we have found an abundance of companies that are well positioned for long-term growth, made the largest contribution. We believe there is an attractive and large opportunity set in European industrial companies that are global leaders in niche segments. Several of our
Columbia Acorn Family of Funds  | Annual Report 2021
25

Manager Discussion of Fund Performance  (continued)
Columbia Acorn European FundSM
  portfolio companies occupy strong positions in customer acquisition and retention through digital platforms, and they have key competitive advantages versus smaller players. We are also focusing on areas such as efficient climate control, factory automation, and the shift toward more environmentally friendly clean energy options.
The Fund’s notable detractors during the period
The materials sector was one of only two sectors where the Fund had holdings in which our stock picks underperformed.
The shortfall was largely a result of weakness in the shares of the Swiss composite engineering company Gurit Holding AG.
Vidrala SA, a Spain-based producer of glass packaging, was another notable detractor in the sector.
We sold the position in Gurit Holding, but Vidrala remained in the portfolio at year-end.
Despite the contribution from Nemetschek noted above, our overall stock selection in information technology detracted from the Fund’s 12-month performance results, as well.
TeamViewer AG, based in Germany, was the leading detractor in both the sector and the Fund as a whole. The stock was hurt by a management shuffle and weaker-than-expected profit margins. We became less enthusiastic on the company’s growth prospects, prompting us to sell the position.
Exasol AG, based in Germany, develops database software for analytics applications. While the firm has been successful in driving adoption of its real-time analytics offering in Europe, the process of gaining traction in the massive U.S. market has proved more gradual than investors expected.
SimCorp AS, a provider of investment management software solutions and services, also detracted due to slower new client signings stemming from COVID-19-related uncertainty. 
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. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. See the Fund’s prospectus for more information on these and other risks.
The views expressed in this report reflect the current views of the respective parties. 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 parties disclaim any responsibility to update such views. These views may not be relied on as investment advice and, because investment decisions for a Columbia Acorn Fund are based on numerous factors, may not be relied on as an indication of trading intent on behalf of any particular Columbia Acorn Fund. References to specific securities should not be construed as a recommendation or investment advice.
26 Columbia Acorn Family of Funds  | Annual Report 2021

Understanding Your Fund’s Expenses
(Unaudited)
As a shareholder, you incur two types of costs. There are shareholder transaction costs, which generally include sales charges on purchases and may include redemption fees. There are also ongoing fund costs, which generally include investment advisory fees, distribution and service (Rule 12b-1) fees, and other Fund expenses. The following information is intended to help you understand your ongoing costs (in dollars) of investing in the Fund and to help you compare these costs with the ongoing costs of investing in other mutual funds.
Analyzing your Fund’s expenses
To illustrate these ongoing costs, we have provided examples and calculated the expenses paid by investors in each share class of the Funds during the period. The actual and hypothetical information in the tables is based on an initial investment of $1,000 at the beginning of the period indicated and held for the entire period. Expense information is calculated two ways and each method provides you with different information. The amount listed in the “Actual” column is calculated using the Funds’ actual operating expenses and total return for the period. You may use the Actual information, together with the amount invested, to estimate the expenses that you paid over the period. Simply divide your account value by $1,000 (for example, an $8,600 account value divided by $1,000 = 8.6), then multiply the results by the expenses paid during the period under the Actual column. The amount listed in the “Hypothetical” column assumes a 5% annual rate of return before expenses (which is not the Funds’ actual return) and then applies the Funds’ actual expense ratio for the period to the hypothetical return. You should not use the hypothetical account values and expenses to estimate either your actual account balance at the end of the period or the expenses you paid during the period. See “Compare with other funds” below for details on how to use the hypothetical data.
In addition to the ongoing expenses which the Funds bear directly, Columbia Thermostat FundSM’s shareholders indirectly bear the Fund’s allocable share of the costs and expenses of each underlying fund in which the Fund invests. You can also estimate the effective expenses paid during the period, which includes the indirect fees associated with investing in the underlying funds, by using the amounts listed in the effective expenses paid during the period column in the “Fund of Funds” table.
Compare with other funds
Since all mutual funds are required to include the same hypothetical calculations about expenses in shareholder reports, you can use this information to compare the ongoing cost of investing in the Funds with other funds. To do so, compare the hypothetical example with the 5% hypothetical examples that appear in the shareholder reports of other funds. As you compare hypothetical examples of other funds, it is important to note that hypothetical examples are meant to highlight the ongoing costs of investing in a fund only and do not reflect any transaction costs, such as sales charges, or redemption or exchange fees. Therefore, the hypothetical calculations are useful in comparing ongoing costs only, and will not help you determine the relative total costs of owning different funds. If transaction costs were included in these calculations, your costs would be higher.
July 1, 2021 — December 31, 2021
  Account value at the
beginning of the
period ($)
Account value at the
end of the
period ($)
Expenses paid during
the period ($)
Fund’s annualized
expense ratio (%)
  Actual Hypothetical Actual Hypothetical Actual Hypothetical Actual
Columbia Acorn® Fund
Class A 1,000.00 1,000.00 1,009.90 1,019.76 5.47 5.50 1.08
Advisor Class 1,000.00 1,000.00 1,010.30 1,021.07 4.15 4.18 0.82
Class C 1,000.00 1,000.00 1,005.60 1,016.03 9.20 9.25 1.82
Institutional Class 1,000.00 1,000.00 1,010.30 1,021.02 4.21 4.23 0.83
Institutional 2 Class 1,000.00 1,000.00 1,011.00 1,021.17 4.06 4.08 0.80
Institutional 3 Class 1,000.00 1,000.00 1,011.30 1,021.42 3.80 3.82 0.75
Columbia Acorn Family of Funds  | Annual Report 2021
27

Understanding Your Fund’s Expenses  (continued)
(Unaudited)
July 1, 2021 — December 31, 2021
  Account value at the
beginning of the
period ($)
Account value at the
end of the
period ($)
Expenses paid during
the period ($)
Fund’s annualized
expense ratio (%)
  Actual Hypothetical Actual Hypothetical Actual Hypothetical Actual
Columbia Acorn International®
Class A 1,000.00 1,000.00 1,040.60 1,019.06 6.27 6.21 1.22
Advisor Class 1,000.00 1,000.00 1,041.60 1,020.32 4.99 4.94 0.97
Class C 1,000.00 1,000.00 1,036.60 1,015.27 10.11 10.01 1.97
Institutional Class 1,000.00 1,000.00 1,041.70 1,020.32 4.99 4.94 0.97
Institutional 2 Class 1,000.00 1,000.00 1,042.00 1,020.57 4.74 4.69 0.92
Institutional 3 Class 1,000.00 1,000.00 1,042.10 1,020.77 4.53 4.48 0.88
Class R 1,000.00 1,000.00 1,039.00 1,017.80 7.55 7.48 1.47
Columbia Acorn USA®
Class A 1,000.00 1,000.00 990.50 1,018.20 6.97 7.07 1.39
Advisor Class 1,000.00 1,000.00 991.70 1,019.46 5.72 5.80 1.14
Class C 1,000.00 1,000.00 986.70 1,014.42 10.72 10.87 2.14
Institutional Class 1,000.00 1,000.00 991.50 1,019.46 5.72 5.80 1.14
Institutional 2 Class 1,000.00 1,000.00 991.80 1,019.76 5.42 5.50 1.08
Institutional 3 Class 1,000.00 1,000.00 992.40 1,019.96 5.22 5.30 1.04
Columbia Acorn International SelectSM
Class A 1,000.00 1,000.00 1,059.70 1,019.06 6.33 6.21 1.22
Advisor Class 1,000.00 1,000.00 1,061.10 1,020.32 5.04 4.94 0.97
Class C 1,000.00 1,000.00 1,055.80 1,015.27 10.21 10.01 1.97
Institutional Class 1,000.00 1,000.00 1,061.10 1,020.32 5.04 4.94 0.97
Institutional 2 Class 1,000.00 1,000.00 1,061.20 1,020.77 4.57 4.48 0.88
Institutional 3 Class 1,000.00 1,000.00 1,061.70 1,021.02 4.31 4.23 0.83
Columbia Acorn European FundSM
Class A 1,000.00 1,000.00 1,090.10 1,017.95 7.59 7.32 1.44
Advisor Class 1,000.00 1,000.00 1,091.40 1,019.21 6.27 6.06 1.19
Class C 1,000.00 1,000.00 1,086.30 1,014.17 11.52 11.12 2.19
Institutional Class 1,000.00 1,000.00 1,091.60 1,019.21 6.27 6.06 1.19
Institutional 2 Class 1,000.00 1,000.00 1,091.90 1,019.46 6.01 5.80 1.14
Institutional 3 Class 1,000.00 1,000.00 1,091.90 1,019.66 5.80 5.60 1.10
Fund of Funds—Columbia Thermostat FundSM
July 1, 2021 — December 31, 2021
  Account value at the
beginning of the
period ($)
Account value at the
end of the
period ($)
Expenses paid during
the period ($)
Fund’s annualized
expense ratio (%)
Effective expenses
paid during the
period ($)
Fund’s effective
annualized
expense ratio (%)
  Actual Hypothetical Actual Hypothetical Actual Hypothetical Actual Actual Hypothetical Actual
Class A 1,000.00 1,000.00 1,002.40 1,022.68 2.52 2.55 0.50 4.29 4.33 0.85
Advisor Class 1,000.00 1,000.00 1,003.30 1,023.95 1.26 1.28 0.25 3.03 3.06 0.60
Class C 1,000.00 1,000.00 998.60 1,018.90 6.30 6.36 1.25 8.06 8.14 1.60
Institutional Class 1,000.00 1,000.00 1,003.30 1,023.95 1.26 1.28 0.25 3.03 3.06 0.60
Institutional 2 Class 1,000.00 1,000.00 1,003.80 1,024.20 1.01 1.02 0.20 2.78 2.81 0.55
Institutional 3 Class 1,000.00 1,000.00 1,003.60 1,024.35 0.86 0.87 0.17 2.63 2.65 0.52
Expenses paid during the period are equal to the annualized expense ratio, multiplied by the average account value over the period and then multiplied by the number of days in the Fund’s most recent fiscal half year and divided by 365.
Except with respect to Columbia Thermostat FundSM, expenses do not include any fees and expenses incurred indirectly by a Fund from the underlying funds in which the Fund may invest (also referred to as “acquired funds”), including affiliated and non-affiliated pooled investments vehicles (including mutual funds and exchange traded funds).
28 Columbia Acorn Family of Funds  | Annual Report 2021

Understanding Your Fund’s Expenses  (continued)
(Unaudited)
In the case of Columbia Thermostat FundSM, effective expenses paid during the period and the Fund’s effective annualized expense ratio include expenses borne directly by the class plus the Fund’s pro rata portion of the ongoing expenses charged by the underlying funds in which it invests using the expense ratio of each class of each underlying fund as of the underlying fund’s most recent shareholder report.
Had the investment manager and/or certain of its affiliates not waived/reimbursed certain fees and expenses for the Funds, account value at the end of the period would have been reduced.
Columbia Acorn Family of Funds  | Annual Report 2021
29

Portfolio of Investments
Columbia Acorn® Fund, December 31, 2021
(Percentages represent value of investments compared to net assets)
Investments in securities
Common Stocks 98.3%
Issuer Shares Value ($)
Communication Services 3.5%
Entertainment 3.5%
Roblox Corp., Class A(a) 538,439 55,545,367
Roku, Inc.(a) 116,894 26,675,211
Take-Two Interactive Software, Inc.(a) 211,000 37,498,920
Zynga, Inc., Class A(a) 5,912,599 37,840,634
Total   157,560,132
Total Communication Services 157,560,132
Consumer Discretionary 18.7%
Auto Components 1.4%
Visteon Corp.(a) 569,901 63,338,797
Diversified Consumer Services 2.3%
Bright Horizons Family Solutions, Inc.(a) 342,825 43,154,811
Chegg, Inc.(a) 1,965,290 60,334,403
Total   103,489,214
Hotels, Restaurants & Leisure 6.2%
Churchill Downs, Inc. 227,000 54,684,300
DraftKings, Inc., Class A(a) 433,250 11,901,378
Planet Fitness, Inc., Class A(a) 1,422,769 128,874,416
Wingstop, Inc. 482,304 83,342,131
Total   278,802,225
Household Durables 1.5%
Skyline Champion Corp.(a) 859,991 67,922,089
Internet & Direct Marketing Retail 2.3%
Etsy, Inc.(a) 430,740 94,306,216
Poshmark, Inc., Class A(a),(b) 580,349 9,883,343
Total   104,189,559
Leisure Products 0.5%
Brunswick Corp. 202,371 20,384,831
Specialty Retail 4.5%
Five Below, Inc.(a) 416,030 86,072,447
Floor & Decor Holdings, Inc.(a) 518,000 67,345,180
Vroom, Inc.(a),(c) 1,932,383 20,850,412
Williams-Sonoma, Inc. 186,700 31,576,571
Total   205,844,610
Total Consumer Discretionary 843,971,325
Common Stocks (continued)
Issuer Shares Value ($)
Consumer Staples 2.2%
Food & Staples Retailing 1.2%
BJ’s Wholesale Club Holdings, Inc.(a) 824,000 55,183,280
Household Products 1.0%
WD-40 Co. 184,759 45,199,442
Total Consumer Staples 100,382,722
Energy 1.5%
Oil, Gas & Consumable Fuels 1.5%
Devon Energy Corp. 669,600 29,495,880
Diamondback Energy, Inc. 247,600 26,703,660
Matador Resources Co. 339,948 12,550,880
Total   68,750,420
Total Energy 68,750,420
Financials 4.3%
Banks 1.3%
Lakeland Financial Corp. 715,615 57,349,386
Capital Markets 3.0%
Ares Management Corp., Class A 459,290 37,326,498
GCM Grosvenor, Inc., Class A(b) 2,226,000 23,373,000
Hamilton Lane, Inc., Class A(b) 211,113 21,875,529
Houlihan Lokey, Inc., Class A 265,400 27,474,208
Open Lending Corp., Class A(a) 1,233,417 27,727,214
Total   137,776,449
Total Financials 195,125,835
Health Care 21.7%
Biotechnology 6.5%
Anika Therapeutics, Inc.(a) 582,331 20,864,920
Argenx SE, ADR(a) 114,951 40,254,691
Exact Sciences Corp.(a) 341,400 26,571,162
Fate Therapeutics, Inc.(a) 213,689 12,502,943
Horizon Therapeutics PLC(a) 538,364 58,014,104
Insmed, Inc.(a) 1,675,370 45,637,079
Intellia Therapeutics, Inc.(a) 183,000 21,637,920
Iovance Biotherapeutics, Inc.(a) 650,700 12,421,863
The accompanying Notes to Financial Statements are an integral part of this statement.
30 Columbia Acorn Family of Funds  | Annual Report 2021

Portfolio of Investments   (continued)
Columbia Acorn® Fund, December 31, 2021
Common Stocks (continued)
Issuer Shares Value ($)
Mirati Therapeutics, Inc.(a) 187,230 27,464,769
Natera, Inc.(a) 307,600 28,726,764
Total   294,096,215
Health Care Equipment & Supplies 3.3%
Align Technology, Inc.(a) 102,250 67,196,655
Globus Medical, Inc., Class A(a) 433,100 31,269,820
Masimo Corp.(a) 168,910 49,453,470
Total   147,919,945
Health Care Providers & Services 4.5%
Amedisys, Inc.(a) 650,005 105,222,810
Chemed Corp. 92,296 48,828,276
Encompass Health Corp. 479,663 31,302,807
P3 Health Partners, Inc.(a),(d),(e),(f) 2,500,000 16,550,000
Total   201,903,893
Health Care Technology 0.7%
Doximity, Inc., Class A(a),(c) 681,102 34,143,643
Life Sciences Tools & Services 6.7%
10X Genomics, Inc., Class A(a) 619,098 92,220,838
Bio-Techne Corp. 159,302 82,413,297
Codexis, Inc.(a) 310,586 9,712,024
Pacific Biosciences of California, Inc.(a) 1,316,600 26,937,636
Repligen Corp.(a) 354,199 93,806,063
Total   305,089,858
Total Health Care 983,153,554
Industrials 14.3%
Electrical Equipment 4.8%
AMETEK, Inc. 343,667 50,532,796
Atkor, Inc.(a) 359,364 39,957,683
Generac Holdings, Inc.(a) 131,180 46,164,866
Plug Power, Inc.(a) 1,723,000 48,640,290
Shoals Technologies Group, Inc., Class A(a) 1,267,675 30,804,502
Total   216,100,137
Machinery 5.1%
IDEX Corp. 133,500 31,548,720
Ingersoll Rand, Inc. 808,068 49,995,167
Kornit Digital Ltd.(a) 499,638 76,069,886
SPX Corp.(a) 1,233,872 73,637,481
Total   231,251,254
Common Stocks (continued)
Issuer Shares Value ($)
Professional Services 2.1%
CoStar Group, Inc.(a) 655,860 51,832,616
ICF International, Inc. 441,000 45,224,550
Total   97,057,166
Trading Companies & Distributors 2.3%
SiteOne Landscape Supply, Inc.(a) 430,151 104,216,984
Total Industrials 648,625,541
Information Technology 27.8%
Communications Equipment 0.8%
Calix, Inc.(a) 432,291 34,570,311
Electronic Equipment, Instruments & Components 1.6%
CDW Corp. 347,683 71,198,525
IT Services 7.1%
Endava PLC, ADR(a) 451,510 75,817,559
EPAM Systems, Inc.(a) 67,994 45,450,589
MongoDB, Inc.(a) 166,250 88,004,437
Shift4 Payments, Inc., Class A(a) 647,419 37,504,983
VeriSign, Inc.(a) 217,675 55,250,269
Wix.com Ltd.(a) 122,120 19,269,315
Total   321,297,152
Semiconductors & Semiconductor Equipment 2.9%
Enphase Energy, Inc.(a) 304,253 55,660,044
Teradyne, Inc. 479,339 78,386,306
Total   134,046,350
Software 15.4%
Avalara, Inc.(a) 496,000 64,038,560
Bill.com Holdings, Inc.(a) 410,636 102,309,959
Blackline, Inc.(a) 426,525 44,162,398
Cadence Design Systems, Inc.(a) 244,059 45,480,395
Crowdstrike Holdings, Inc., Class A(a) 162,291 33,229,082
DocuSign, Inc.(a) 130,620 19,894,732
Elastic NV(a) 213,424 26,270,360
Five9, Inc.(a) 419,315 57,580,336
HubSpot, Inc.(a) 52,050 34,308,758
Olo, Inc., Class A(a) 991,000 20,622,710
Trade Desk, Inc. (The), Class A(a) 1,357,784 124,427,326
Voyager Digital Ltd.(a),(c) 1,953,276 24,382,172
 
The accompanying Notes to Financial Statements are an integral part of this statement.
Columbia Acorn Family of Funds  | Annual Report 2021
31

Portfolio of Investments   (continued)
Columbia Acorn® Fund, December 31, 2021
Common Stocks (continued)
Issuer Shares Value ($)
Zendesk, Inc.(a) 362,877 37,844,442
Zscaler, Inc.(a) 202,044 64,922,799
Total   699,474,029
Total Information Technology 1,260,586,367
Materials 2.6%
Chemicals 2.6%
Albemarle Corp. 268,600 62,790,622
Avient Corp. 958,000 53,600,100
Total   116,390,722
Total Materials 116,390,722
Real Estate 1.7%
Real Estate Management & Development 1.7%
Colliers International Group, Inc. 336,817 50,067,847
FirstService Corp. 132,500 26,032,275
Total   76,100,122
Total Real Estate 76,100,122
Total Common Stocks
(Cost $3,563,490,313)
4,450,646,740
Securities Lending Collateral 0.8%
Issuer Shares Value ($)
Dreyfus Government Cash Management Fund, Institutional Shares, 0.030%(g),(h) 36,269,919 36,269,919
Total Securities Lending Collateral
(Cost $36,269,919)
36,269,919
Money Market Funds 1.8%
  Shares Value ($)
Columbia Short-Term Cash Fund, 0.085%(b),(g) 81,677,236 81,660,901
Total Money Market Funds
(Cost $81,660,223)
81,660,901
Total Investments in Securities
(Cost: $3,681,420,455)
4,568,577,560
Obligation to Return Collateral for Securities Loaned   (36,269,919)
Other Assets & Liabilities, Net   (3,683,971)
Net Assets 4,528,623,670
 
Notes to Portfolio of Investments
(a) Non-income producing investment.
(b) As defined in the Investment Company Act of 1940, as amended, an affiliated company is one in which the Fund owns 5% or more of the company’s outstanding voting securities, or a company which is under common ownership or control with the Fund. The value of the holdings and transactions in these affiliated companies during the year ended December 31, 2021 are as follows:
    
Affiliated issuers Beginning
of period($)
Purchases($) Sales($) Net change in
unrealized
appreciation
(depreciation)($)
End of
period($)
Realized gain
(loss)($)
Dividends($) End of
period shares
Columbia Short-Term Cash Fund, 0.085%
  39,795,717 1,744,139,977 (1,702,270,267) (4,526) 81,660,901 (1,213) 58,825 81,677,236
ePlus, Inc.‡,†
  47,101,170 (79,036,447) 7,473,170
GCM Grosvenor, Inc., Class A
  70,639 23,373,000 734,580 2,226,000
Hamilton Lane, Inc., Class A‡,†
  48,305,512 (55,510,979) 4,493,833 821,911
Kiniksa Pharmaceuticals Ltd., Class A
  28,164,513 (31,166,939) 3,002,426 (4,332,697)
Poshmark, Inc., Class A‡,†
  57,202,730 (25,734,533) (15,581,834)
Total 67,960,230     3,068,539 105,033,901 (7,948,741) 1,615,316  
    
Issuer was not an affiliate at the beginning of period.
Issuer was not an affiliate at the end of period.
    
The accompanying Notes to Financial Statements are an integral part of this statement.
32 Columbia Acorn Family of Funds  | Annual Report 2021

Portfolio of Investments   (continued)
Columbia Acorn® Fund, December 31, 2021
Notes to Portfolio of Investments  (continued)
(c) All or a portion of this security was on loan at December 31, 2021. The total market value of securities on loan at December 31, 2021 was $33,010,589.
(d) Represents fair value as determined in good faith under procedures approved by the Board of Trustees. At December 31, 2021, the total value of these securities amounted to $16,550,000, which represents 0.37% of total net assets.
(e) Denotes a restricted security, which is subject to legal or contractual restrictions on resale under federal securities laws. Disposal of a restricted investment may involve time-consuming negotiations and expenses, and prompt sale at an acceptable price may be difficult to achieve. Private placement securities are generally considered to be restricted, although certain of those securities may be traded between qualified institutional investors under the provisions of Section 4(a)(2) and Rule 144A. The Fund will not incur any registration costs upon such a trade. These securities are valued at fair value determined in good faith under consistently applied procedures established by the Fund’s Board of Trustees. At December 31, 2021, the total market value of these securities amounted to $16,550,000, which represents 0.37% of total net assets. Additional information on these securities is as follows:
    
Security Acquisition
Dates
Shares Cost ($) Value ($)
P3 Health Partners, Inc. 05/26/2021 2,500,000 25,000,000 16,550,000
    
(f) Valuation based on significant unobservable inputs.
(g) The rate shown is the seven-day current annualized yield at December 31, 2021.
(h) Investment made with cash collateral received from securities lending activity.
Abbreviation Legend
ADR American Depositary Receipt
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 net asset values are published each day and exchange traded foreign equities that are not typically statistically fair valued. Typical Level 2 securities include exchange traded foreign equities that are traded in the European region or Asia Pacific region time zones which are typically statistically fair valued, forward foreign currency exchange contracts and short-term investments valued at amortized cost. Additionally, securities fair valued by Columbia Wanger Asset Management’s Valuation Committee (the Committee) 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.
The Committee is responsible for applying the Columbia Acorn Trust Portfolio Pricing Policy and the Columbia Wanger Asset Management pricing procedures (the Policies), which are approved by and subject to the oversight of the Board of Trustees.
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 Columbia Wanger Asset Management believes that available market quotations are unreliable. The Committee also reviews the continuing appropriateness of the Policies. In circumstances where a security has been fair valued, the Committee will also review the continuing appropriateness of the current value of the security. 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 is a summary of the inputs used to value the Fund’s investments at December 31, 2021:
  Level 1 ($) Level 2 ($) Level 3 ($) Total ($)
Investments in Securities        
Common Stocks        
Communication Services 157,560,132 157,560,132
Consumer Discretionary 843,971,325 843,971,325
Consumer Staples 100,382,722 100,382,722
Energy 68,750,420 68,750,420
Financials 195,125,835 195,125,835
Health Care 966,603,554 16,550,000 983,153,554
The accompanying Notes to Financial Statements are an integral part of this statement.
Columbia Acorn Family of Funds  | Annual Report 2021
33

Portfolio of Investments   (continued)
Columbia Acorn® Fund, December 31, 2021
Fair value measurements  (continued)
  Level 1 ($) Level 2 ($) Level 3 ($) Total ($)
Industrials 648,625,541 648,625,541
Information Technology 1,260,586,367 1,260,586,367
Materials 116,390,722 116,390,722
Real Estate 76,100,122 76,100,122
Total Common Stocks 4,434,096,740 16,550,000 4,450,646,740
Securities Lending Collateral 36,269,919 36,269,919
Money Market Funds 81,660,901 81,660,901
Total Investments in Securities 4,552,027,560 16,550,000 4,568,577,560
See the Portfolio of Investments for all investment classifications not indicated in the table.
The Fund does not hold any significant investments (greater than one percent of net assets) categorized as Level 3.
The accompanying Notes to Financial Statements are an integral part of this statement.
34 Columbia Acorn Family of Funds  | Annual Report 2021

Portfolio of Investments
Columbia Acorn International®, December 31, 2021
(Percentages represent value of investments compared to net assets)
Investments in securities
Common Stocks 98.9%
Issuer Shares Value ($)
Australia 5.3%
Bapcor Ltd. 8,198,062 41,787,728
carsales.com Ltd. 990,365 18,095,622
IDP Education Ltd. 1,459,389 36,765,335
Pro Medicus Ltd. 289,845 13,154,462
Temple & Webster Group Ltd.(a) 1,845,783 14,449,564
Total 124,252,711
Austria 0.6%
S&T AG(b) 878,104 14,588,437
Brazil 1.8%
Notre Dame Intermedica Participacoes SA 1,756,438 19,030,706
TOTVS SA 4,694,127 24,136,409
Total 43,167,115
Canada 2.6%
Altus Group Ltd. 456,750 25,625,952
Osisko Gold Royalties Ltd. 2,866,342 35,077,255
Total 60,703,207
China 2.5%
Shenzhou International Group Holdings Ltd. 1,145,600 22,183,034
Silergy Corp. 194,000 35,113,285
Total 57,296,319
Denmark 3.6%
ALK-Abello AS(a) 76,663 40,255,982
SimCorp AS 394,321 42,977,746
Total 83,233,728
Finland 0.8%
Valmet OYJ 419,361 17,980,387
France 0.6%
Robertet SA 12,149 13,485,846
Germany 7.5%
Eckert & Ziegler Strahlen- und Medizintechnik AG 249,713 26,686,191
Hypoport SE(a) 93,752 54,374,471
Jenoptik AG 1,073,686 45,306,306
Nemetschek SE 384,791 49,200,954
Total 175,567,922
Common Stocks (continued)
Issuer Shares Value ($)
Greece 0.5%
JUMBO SA 882,707 12,662,520
Italy 4.7%
Amplifon SpA 977,347 52,589,300
Carel Industries SpA 289,182 8,745,373
GVS SpA 1,147,087 13,768,727
Nexi SpA(a) 2,125,392 33,679,810
Total 108,783,210
Japan 16.5%
Aruhi Corp. 1,484,700 13,491,683
CyberAgent, Inc. 682,300 11,373,825
Daifuku Co., Ltd. 458,900 37,526,510
Daiseki Co., Ltd. 932,119 41,408,850
Disco Corp. 66,000 20,173,068
Elecom Co., Ltd. 1,180,700 15,539,751
Fuso Chemical Co., Ltd. 561,800 23,703,810
Hikari Tsushin, Inc. 424,828 65,426,745
Hoshizaki Corp. 149,200 11,225,489
NSD Co., Ltd. 588,100 10,682,687
Obic Co., Ltd. 139,100 26,032,456
Seiren Co., Ltd. 861,000 18,863,267
Sekisui Chemical Co., Ltd. 2,216,400 37,067,418
Shima Seiki Manufacturing Ltd. 325,900 5,590,745
Simplex Holdings, Inc.(a) 799,700 19,734,355
Solasto Corp. 1,803,300 19,374,629
Valqua Ltd. 407,600 9,607,063
Total 386,822,351
Malta 0.5%
Kindred Group PLC 1,069,580 12,671,973
Mexico 1.1%
Corporación Inmobiliaria Vesta SAB de CV 12,567,607 25,189,841
Netherlands 4.3%
Argenx SE, ADR(a) 114,759 40,187,454
BE Semiconductor Industries NV 144,137 12,253,484
IMCD NV 222,632 49,202,402
Total 101,643,340
The accompanying Notes to Financial Statements are an integral part of this statement.
Columbia Acorn Family of Funds  | Annual Report 2021
35

Portfolio of Investments   (continued)
Columbia Acorn International®, December 31, 2021
Common Stocks (continued)
Issuer Shares Value ($)
New Zealand 1.9%
Fisher & Paykel Healthcare Corp., Ltd. 1,978,513 44,325,753
Russian Federation 1.6%
TCS Group Holding PLC, GDR(c) 448,967 37,847,872
Singapore 1.1%
Mapletree Logistics Trust 17,732,544 25,008,848
South Korea 2.4%
Koh Young Technology, Inc.(a) 1,266,645 25,229,265
Korea Investment Holdings Co., Ltd.(a) 442,611 29,987,138
Total 55,216,403
Spain 1.9%
Befesa SA 308,579 23,677,972
Vidrala SA 213,082 21,008,628
Total 44,686,600
Sweden 9.8%
AddTech AB, B Shares 2,032,021 48,332,282
Dometic Group AB 2,163,171 28,396,471
Hexagon AB, Class B 4,274,829 67,715,642
Munters Group AB 3,142,036 24,322,770
Sectra AB, Class B(a) 996,824 22,084,965
Sweco AB, Class B 2,035,816 38,308,843
Total 229,160,973
Switzerland 3.6%
Belimo Holding AG, Registered Shares 66,374 42,146,582
Inficon Holding AG 18,546 27,113,314
Montana Aerospace AG(a),(c) 391,115 14,529,459
Total 83,789,355
Taiwan 5.5%
Parade Technologies Ltd. 756,000 57,516,566
Sinbon Electronics Co., Ltd. 2,393,000 24,513,062
Universal Vision Biotechnology Co., Ltd. 1,110,000 11,339,944
Voltronic Power Technology Corp. 613,408 34,220,807
Total 127,590,379
Common Stocks (continued)
Issuer Shares Value ($)
United Kingdom 15.2%
Abcam PLC(a) 625,142 14,663,969
Auto Trader Group PLC 2,123,901 21,270,608
Dechra Pharmaceuticals PLC 773,015 55,869,431
Diploma PLC 688,467 31,563,804
Genus PLC 368,303 24,700,928
Halma PLC 460,960 19,986,715
Intermediate Capital Group PLC 1,765,720 52,584,435
Rentokil Initial PLC 5,597,778 44,310,603
Rightmove PLC 4,790,311 51,691,274
Safestore Holdings PLC 645,592 12,312,420
Spirax-Sarco Engineering PLC 123,404 26,856,471
Total 355,810,658
United States 2.6%
Inter Parfums, Inc. 576,834 61,663,555
Vietnam 0.4%
Asia Commercial Bank JSC(a) 6,638,667 10,039,269
Total Common Stocks
(Cost $1,397,467,893)
2,313,188,572
Securities Lending Collateral 0.4%
Dreyfus Government Cash Management Fund, Institutional Shares, 0.030%(d),(e) 10,493,519 10,493,519
Total Securities Lending Collateral
(Cost $10,493,519)
10,493,519
Money Market Funds 1.0%
  Shares Value ($)
Columbia Short-Term Cash Fund, 0.085%(d),(f) 22,668,846 22,664,312
Total Money Market Funds
(Cost $22,664,312)
22,664,312
Total Investments in Securities
(Cost $1,430,625,724)
2,346,346,403
Obligation to Return Collateral for Securities Loaned   (10,493,519)
Other Assets & Liabilities, Net   3,935,189
Net Assets $2,339,788,073
 
The accompanying Notes to Financial Statements are an integral part of this statement.
36 Columbia Acorn Family of Funds  | Annual Report 2021

Portfolio of Investments   (continued)
Columbia Acorn International®, December 31, 2021
Notes to Portfolio of Investments
(a) Non-income producing investment.
(b) All or a portion of this security was on loan at December 31, 2021. The total market value of securities on loan at December 31, 2021 was $10,018,113.
(c) Represents privately placed and other securities and instruments exempt from Securities and Exchange Commission registration (collectively, private placements), such as Section 4(a)(2) and Rule 144A eligible securities, which are often sold only to qualified institutional buyers. At December 31, 2021, the total value of these securities amounted to $52,377,331, which represents 2.24% of total net assets.
(d) The rate shown is the seven-day current annualized yield at December 31, 2021.
(e) Investment made with cash collateral received from securities lending activity.
(f) As defined in the Investment Company Act of 1940, as amended, an affiliated company is one in which the Fund owns 5% or more of the company’s outstanding voting securities, or a company which is under common ownership or control with the Fund. The value of the holdings and transactions in these affiliated companies during the year ended December 31, 2021 are as follows:
    
Affiliated issuers Beginning
of period($)
Purchases($) Sales($) Net change in
unrealized
appreciation
(depreciation)($)
End of
period($)
Realized gain
(loss)($)
Dividends($) End of
period shares
Columbia Short-Term Cash Fund, 0.085%
  61,934,514 628,270,129 (667,540,331) 22,664,312 (3,531) 35,467 22,668,846
Abbreviation Legend
ADR American Depositary Receipt
GDR Global Depositary Receipt
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: