N-CSRS 1 a16-14771_2ncsrs.htm N-CSRS

 

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

 

FORM N-CSR

 

CERTIFIED SHAREHOLDER REPORT OF REGISTERED
MANAGEMENT INVESTMENT COMPANIES

 

Investment Company Act file number

811-01829

 

Columbia Acorn Trust

(Exact name of registrant as specified in charter)

 

227 W. Monroe Street

Suite 3000

Chicago, IL

 

60606

(Address of principal executive offices)

 

(Zip code)

 

Mary C. Moynihan

Perkins Coie LLP

700 13th Street, NW

Suite 600

Washington, DC 20005

 

Paul B. Goucher, Esq.

Columbia Management Investment Advisers, LLC

100 Park Avenue

New York, New York 10017

 

P. Zachary Egan

Columbia Acorn Trust

227 West Monroe Street, Suite 3000

Chicago, Illinois 60606

(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:

June 30, 2016

 

 

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, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

 



 

Item 1. Reports to Stockholders.

 



SEMIANNUAL REPORT

June 30, 2016

COLUMBIA ACORN FAMILY OF FUNDS

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

Columbia Acorn® Fund

Columbia Acorn International®

Columbia Acorn USA®

Columbia Acorn International SelectSM

Columbia Acorn SelectSM

Columbia Thermostat FundSM

Columbia Acorn Emerging Markets FundSM

Columbia Acorn European FundSM



COLUMBIA ACORN FAMILY OF FUNDS

>NET ASSET VALUE PER SHARE as of 6/30/16

  Columbia
Acorn Fund®
  Columbia
Acorn
International®
  Columbia
Acorn
USA®
  Columbia
Acorn
International
SelectSM
  Columbia
Acorn
SelectSM
  Columbia
Thermostat
FundSM
  Columbia
Acorn
Emerging
Markets
FundSM
  Columbia
Acorn
European
FundSM
 

Class A

 

$

15.57

   

$

38.28

   

$

17.80

   

$

20.93

   

$

12.58

   

$

14.50

   

$

10.36

   

$

14.16

   

Class B

   

N/A

   

$

36.88

     

N/A

     

N/A

     

N/A

     

N/A

     

N/A

     

N/A

   

Class C

 

$

11.07

   

$

36.73

   

$

13.46

   

$

19.51

   

$

9.15

   

$

14.55

   

$

10.28

   

$

14.00

   

Class I

 

$

17.40

   

$

38.42

   

$

20.01

   

$

21.22

   

$

14.01

     

N/A

   

$

10.41

   

$

14.17

   

Class R

   

N/A

   

$

38.20

     

N/A

     

N/A

     

N/A

     

N/A

     

N/A

     

N/A

   

Class R4

 

$

17.80

   

$

38.64

   

$

20.44

   

$

21.36

   

$

14.33

   

$

14.39

   

$

10.46

   

$

14.24

   

Class R5

 

$

17.89

   

$

38.36

   

$

20.50

   

$

21.35

   

$

14.38

   

$

14.41

   

$

10.46

   

$

14.31

   

Class Y

 

$

17.97

   

$

38.68

   

$

20.61

   

$

21.34

   

$

14.47

   

$

14.39

   

$

10.37

     

N/A

   

Class Z

 

$

17.31

   

$

38.37

   

$

19.78

   

$

21.21

   

$

13.88

   

$

14.32

   

$

10.39

   

$

14.18

   

                

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

2016 MID-YEAR DISTRIBUTIONS

The following table lists the mid-year distributions for the Columbia Acorn Family of Funds. The record date was June 6, 2016, and the ex-dividend and payable date was June 7, 2016. The information provided for each Fund applies to all share classes of the Fund.

Fund (all share classes)   Short-Term
Capital Gain
  Long-Term
Capital Gain
  Ordinary
Income
 

Columbia Acorn Fund

   

None

     

2.05420

     

None

   

Columbia Acorn International

   

None

     

0.25773

     

None

   

Columbia Acorn USA

   

None

     

2.67186

     

None

   

Columbia Acorn International Select

   

None

     

None

     

None

   

Columbia Acorn Select

   

None

     

1.22021

     

None

   

Columbia Thermostat Fund

   

None

     

0.27114

     

0.04997

   

Columbia Acorn Emerging Markets Fund

   

None

     

None

     

None

   

Columbia Acorn European Fund

   

None

     

None

     

0.02638

   

      

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

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




A View on Brexit

Global equity markets were caught on the back foot by the outcome of the UK referendum on continued European Union (EU) membership. The long-term political and economic implications of this decision are potentially vast and impossible to discern at this stage, not least because they will be shaped by how policymakers respond. As investors globally reprice risk and reposition portfolios in light of currency sensitivity and how they expect this outcome to bear differently on sectors, countries and companies, there will be mispricing opportunities. This is good for stock pickers and we expect to be active. We will be looking closely at how strong players in diverse industries might improve their competitive positions, as growth opportunities become more scarce and costs of capital among competitors more differentiated. We expect the relatively high balance sheet and business model quality of the stocks that we hold in the Columbia Acorn Funds to prove helpful in coming quarters because the risk premium has gone up, as evidenced by increased volatility, compressed multiples in some pockets of the market such as European banks, and sharp currency swings.

This political development is nonetheless clearly a negative one. The United Kingdom is the fifth largest economy in the world and the second largest within the EU. It has been a member of the European Economic Community (precursor to the EU) since 1973.i The UK exit raises uncertainties about global growth, heightens risk aversion, and it will preoccupy European policymakers at a time when they are already challenged by anemic growth, high unemployment, refugee immigration flows, and international and domestic security concerns.

While many market observers view the outcome of the referendum as a comment on, and existential threat to, the overall European integration project, it may, rather, reflect a larger process at work, namely increasing middle-class discontent with the perceived consequences of globalization in industrialized democracies. Rising populism and nativist resentments in Europe and the United States could be harbingers of future policy regimes that place less value on minimizing trade friction, and the mobility of capital and labor, all of which have contributed to global prosperity. The evolving framework for global trade and investment over the last 25 years has been an enormous engine of global growth. During this period, a substantial percentage of the world's population once living within largely economically isolated communist states was integrated into the modern global economy as producers and consumers. This has

raised standards of living in emerging markets and reduced the cost of consumer goods in industrialized countries, while creating new and growing markets for the sort of technologically sophisticated exports that support high-paying jobs in industrialized countries.

The Columbia Acorn Funds have benefited meaningfully from these trends. With Brexit, the EU will lose its strongest advocate of economic liberalism, which has served as an important counterpoint to statist perspectives in Germany and France. At a minimum, it appears that domestic policies are poised to pivot toward the populist issue of economic inequality, which in Europe may manifest itself in a slowdown or reversal of structural reforms in EU labor markets, with negative consequences for productivity and, with it, standards of living. Fiscal tightening, where necessary, could be scaled back as a salve to populists, and it seems likely that industrialized countries will see increased constraints on immigration, even where demographically driven labor shortages exist.

While this could well be regarded as overall bad news for asset owners, opportunities will likely present themselves. For many years, the Columbia Acorn Funds have explored how factory automation is deployed to reduce labor costs or to replace labor altogether, trends which could be accelerated by a reduction in immigration. London will fight hard to retain its role as the center of European finance, but bank chiefs are already talking about decamping elsewhere, which could create opportunity in continental European real estate and construction. As corporate investment decision-making and household spending slow amidst the uncertainty, fiscal stimulus could be sought via public infrastructure projects, which would be good for constructors and suppliers of building materials. Public policy that increases labor's share of income would benefit consumer companies oriented to a lower middle class demographic. Other policy interventions could result in continued ultra-low interest rates, with implications for interest-rate sensitive businesses. In any case, it seems that earnings growth will continue to be a scarce factor in a low-growth world.

P. Zachary Egan

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

i  http://ukandeu.ac.uk/fact-figures/when-did-britain-decide-to-join-the-european-union/



COLUMBIA ACORN FAMILY OF FUNDS

TABLE OF CONTENTS

Description of Indexes

   

1

   

Share Class Performance

   

2

   

Fund Performance vs. Benchmarks

   

3

   

Columbia Acorn® Fund

 

In a Nutshell

   

4

   

At a Glance

   

5

   

Statement of Investments

   

23

   

Columbia Acorn International®

 

In a Nutshell

   

6

   

At a Glance

   

7

   

Statement of Investments

   

30

   

Portfolio Diversification

   

36

   

Columbia Acorn USA®

 

In a Nutshell

   

8

   

At a Glance

   

9

   

Statement of Investments

   

37

   

Columbia Acorn International SelectSM

 

In a Nutshell

   

10

   

At a Glance

   

11

   

Statement of Investments

   

42

   

Portfolio Diversification

   

45

   

Columbia Acorn SelectSM

 

In a Nutshell

   

12

   

At a Glance

   

13

   

Statement of Investments

   

46

   

Columbia Thermostat FundSM

 

In a Nutshell

   

14

   

At a Glance

   

15

   

Statement of Investments

   

49

   

Columbia Acorn Emerging Markets FundSM

 

In a Nutshell

   

16

   

At a Glance

   

17

   

Statement of Investments

   

51

   

Portfolio Diversification

   

55

   

Columbia Acorn European FundSM

 

In a Nutshell

   

18

   

At a Glance

   

19

   

Statement of Investments

   

56

   

Portfolio Diversification

   

59

   

Understanding Your Expenses

   

20

   

Columbia Acorn Family of Funds

 

Statements of Assets and Liabilities

   

60

   

Statements of Operations

   

62

   

Statements of Changes in Net Assets

   

64

   

Financial Highlights

   

70

   

Notes to Financial Statements

   

86

   

Board Approval of the Advisory Agreement

   

97

   

Expense Information

   

102

   


COLUMBIA ACORN FAMILY OF FUNDS

DESCRIPTIONS OF INDEXES INCLUDED IN THIS REPORT

•  50/50 Blended Benchmark, established by the Fund's investment manager, is an equally weighted custom composite of Columbia Thermostat Fund's primary equity and primary debt benchmarks, the S&P 500® Index and the Barclays U.S. Aggregate Bond Index, respectively. The percentage of the Fund's assets allocated to underlying stock and bond portfolio funds will vary, and accordingly the composition of the Fund's portfolio will not always reflect the composition of the 50/50 Blended Benchmark.

•  Barclays U.S. Aggregate Bond Index is a market value-weighted index that tracks the daily price, coupon, pay-downs and total return performance of fixed-rate, publicly placed, dollar-denominated and non-convertible investment grade debt issues with at least $250 million par amount outstanding and with at least one year to final maturity.

•  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.

•  MSCI ACWI ex USA Index (Net) captures a large- and mid-cap representation across 22 of 23 developed market countries (excluding the U.S.) and 23 emerging market countries. The index covers approximately 85% of the global equity opportunity set outside the United States.

•  MSCI ACWI ex USA SMID Cap Index (Net) captures a mid- and small-cap representation across 22 of 23 developed market countries (excluding the U.S.) and 23 emerging market countries. The index covers approximately 28% of the free float-adjusted market capitalization in each country.

•  MSCI Emerging Markets SMID Cap Index (Net) captures a mid- and small-cap representation across 23 emerging market countries. The index covers approximately 29% of the free float-adjusted market capitalization in each country.

•  Russell 2000 Index measures the performance of the 2,000 smallest companies in the Russell 3000 Index, which represents approximately 10% of the total market capitalization of the Russell 3000 Index.

•  Russell 2500 Index measures the performance of the 2,500 smallest companies in the Russell 3000 Index, which represents approximately 17% of the total market capitalization of the Russell 3000 Index.

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

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

•  S&P Emerging Markets Between $500M and $5B® Index represents the institutionally investable capital of 22 emerging market countries, as determined by S&P, with market caps ranging between $500 million to $5 billion. The index currently consists of the following emerging market country indexes: Brazil, Chile, China, Colombia, Czech Republic, Egypt, Greece, Hungary, India, Indonesia, Malaysia, Mexico, Peru, Philippines, Poland, Qatar, Russia, South Africa, Taiwan, Thailand, Turkey and United Arab Emirates.

•  S&P Europe Between $500M and $5B® Index represents the institutionally investable capital of 16 European countries, as determined by S&P, with market caps ranging between $500 million to $5 billion. The index consists of the following European countries: Austria, Belgium, Denmark, Finland, France, Germany, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

•  S&P Global Ex-U.S. Between $500M and $5B® Index is a subset of the broad market selected by the index sponsor that represents the mid- and small-cap developed and emerging markets, excluding the United States.

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

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


1



COLUMBIA ACORN FAMILY OF FUNDS

SHARE CLASS PERFORMANCE Average Annual Total Returns through 6/30/16

 

Class A

 

Class B

 

Class C

 

Class I

 

Class R

 

Class R4

 

Class R5

 

Class Y

 

Class Z

 

  Without
Sales
Charge
  With
Sales
Charge
  Without
Sales
Charge
  With
Sales
Charge
  Without
Sales
Charge
  With
Sales
Charge
                     

 

Columbia Acorn® Fund

 

Year to date*

   

-0.37

%

   

-6.13

%

   

N/A

     

N/A

     

-0.74

%

   

-1.58

%

   

-0.18

%

   

N/A

     

-0.23

%

   

-0.18

%

   

-0.18

%

   

-0.18

%

 
1 year    

-8.16

%

   

-13.44

%

   

N/A

     

N/A

     

-8.82

%

   

-9.24

%

   

-7.82

%

   

N/A

     

-8.01

%

   

-7.85

%

   

-7.83

%

   

-7.84

%

 
5 years    

6.05

%

   

4.80

%

   

N/A

     

N/A

     

5.28

%

   

5.28

%

   

6.42

%

   

N/A

     

6.30

%

   

6.37

%

   

6.41

%

   

6.36

%

 
10 years    

5.96

%

   

5.34

%

   

N/A

     

N/A

     

5.16

%

   

5.16

%

   

6.31

%

   

N/A

     

6.24

%

   

6.28

%

   

6.30

%

   

6.27

%

 

Columbia Acorn International®

 

Year to date*

   

-1.42

%

   

-7.08

%

   

-1.78

%

   

-6.66

%

   

-1.79

%

   

-2.77

%

   

-1.24

%

   

-1.60

%

   

-1.33

%

   

-1.26

%

   

-1.23

%

   

-1.29

%

 
1 year    

-7.65

%

   

-12.96

%

   

-8.49

%

   

-12.90

%

   

-8.33

%

   

-9.21

%

   

-7.30

%

   

-8.01

%

   

-7.46

%

   

-7.34

%

   

-7.30

%

   

-7.40

%

 
5 years    

2.65

%

   

1.44

%

   

1.85

%

   

1.51

%

   

1.89

%

   

1.89

%

   

3.04

%

   

2.28

%

   

2.90

%

   

2.99

%

   

3.02

%

   

2.96

%

 
10 years    

4.79

%

   

4.17

%

   

4.06

%

   

4.06

%

   

3.99

%

   

3.99

%

   

5.18

%

   

4.46

%

   

5.10

%

   

5.14

%

   

5.16

%

   

5.13

%

 

Columbia Acorn USA®

 

Year to date*

   

0.82

%

   

-5.00

%

   

N/A

     

N/A

     

0.46

%

   

-0.38

%

   

1.01

%

   

N/A

     

0.90

%

   

0.94

%

   

1.03

%

   

0.92

%

 
1 year    

-7.40

%

   

-12.72

%

   

N/A

     

N/A

     

-8.05

%

   

-8.57

%

   

-7.02

%

   

N/A

     

-7.21

%

   

-7.10

%

   

-7.03

%

   

-7.18

%

 
5 years    

6.97

%

   

5.72

%

   

N/A

     

N/A

     

6.23

%

   

6.23

%

   

7.40

%

   

N/A

     

7.25

%

   

7.30

%

   

7.35

%

   

7.24

%

 
10 years    

5.75

%

   

5.13

%

   

N/A

     

N/A

     

4.97

%

   

4.97

%

   

6.12

%

   

N/A

     

6.04

%

   

6.07

%

   

6.09

%

   

6.04

%

 

Columbia Acorn International SelectSM

 

Year to date*

   

-1.88

%

   

-7.51

%

   

N/A

     

N/A

     

-2.25

%

   

-3.23

%

   

-1.62

%

   

N/A

     

-1.75

%

   

-1.70

%

   

-1.70

%

   

-1.71

%

 
1 year    

-6.61

%

   

-11.98

%

   

N/A

     

N/A

     

-7.37

%

   

-8.28

%

   

-6.21

%

   

N/A

     

-6.35

%

   

-6.29

%

   

-6.24

%

   

-6.36

%

 
5 years    

1.76

%

   

0.57

%

   

N/A

     

N/A

     

0.97

%

   

0.97

%

   

2.14

%

   

N/A

     

2.05

%

   

2.10

%

   

2.13

%

   

2.07

%

 
10 years    

4.28

%

   

3.66

%

   

N/A

     

N/A

     

3.45

%

   

3.45

%

   

4.66

%

   

N/A

     

4.60

%

   

4.63

%

   

4.64

%

   

4.61

%

 

Columbia Acorn SelectSM

 

Year to date*

   

-1.32

%

   

-7.00

%

   

N/A

     

N/A

     

-1.77

%

   

-2.64

%

   

-1.13

%

   

N/A

     

-1.17

%

   

-1.17

%

   

-1.17

%

   

-1.21

%

 
1 year    

-7.56

%

   

-12.86

%

   

N/A

     

N/A

     

-8.25

%

   

-8.79

%

   

-7.21

%

   

N/A

     

-7.33

%

   

-7.27

%

   

-7.24

%

   

-7.28

%

 
5 years    

5.48

%

   

4.24

%

   

N/A

     

N/A

     

4.70

%

   

4.70

%

   

5.89

%

   

N/A

     

5.75

%

   

5.80

%

   

5.83

%

   

5.78

%

 
10 years    

5.17

%

   

4.55

%

   

N/A

     

N/A

     

4.36

%

   

4.36

%

   

5.54

%

   

N/A

     

5.46

%

   

5.49

%

   

5.50

%

   

5.48

%

 

Columbia Thermostat FundSM

 

Year to date*

   

3.57

%

   

-2.37

%

   

N/A

     

N/A

     

3.20

%

   

2.20

%

   

N/A

     

N/A

     

3.67

%

   

3.74

%

   

3.74

%

   

3.69

%

 
1 year    

2.53

%

   

-3.37

%

   

N/A

     

N/A

     

1.74

%

   

0.75

%

   

N/A

     

N/A

     

2.75

%

   

2.82

%

   

2.81

%

   

2.76

%

 
5 years    

6.21

%

   

4.96

%

   

N/A

     

N/A

     

5.42

%

   

5.42

%

   

N/A

     

N/A

     

6.45

%

   

6.48

%

   

6.51

%

   

6.46

%

 
10 years    

5.88

%

   

5.25

%

   

N/A

     

N/A

     

5.08

%

   

5.08

%

   

N/A

     

N/A

     

6.13

%

   

6.15

%

   

6.16

%

   

6.13

%

 

Columbia Acorn Emerging Markets FundSM

 

Year to date*

   

1.17

%

   

-4.60

%

   

N/A

     

N/A

     

0.78

%

   

-0.22

%

   

1.46

%

   

N/A

     

1.36

%

   

1.36

%

   

1.37

%

   

1.27

%

 
1 year    

-14.75

%

   

-19.63

%

   

N/A

     

N/A

     

-15.39

%

   

-16.23

%

   

-14.33

%

   

N/A

     

-14.46

%

   

-14.37

%

   

-14.35

%

   

-14.52

%

 

Life of Fund

   

1.44

%

   

0.21

%

   

N/A

     

N/A

     

0.71

%

   

0.71

%

   

1.84

%

   

N/A

     

1.77

%

   

1.80

%

   

1.83

%

   

1.72

%

 

Columbia Acorn European FundSM

 

Year to date*

   

-3.84

%

   

-9.37

%

   

N/A

     

N/A

     

-4.14

%

   

-5.10

%

   

-3.70

%

   

N/A

     

-3.75

%

   

-3.73

%

   

N/A

     

-3.70

%

 
1 year    

-6.08

%

   

-11.49

%

   

N/A

     

N/A

     

-6.74

%

   

-7.67

%

   

-5.78

%

   

N/A

     

-5.82

%

   

-5.83

%

   

N/A

     

-5.84

%

 

Life of Fund

   

8.27

%

   

6.96

%

   

N/A

     

N/A

     

7.48

%

   

7.48

%

   

8.59

%

   

N/A

     

8.56

%

   

8.55

%

   

N/A

     

8.55

%

 

*Not annualized.

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

All results shown assume reinvestment of distributions during the period. Returns do not reflect the deduction of taxes that a shareholder may pay on Fund distributions or on the redemption of Fund shares. Performance results may reflect the effect of any fee waivers or reimbursements of Fund expenses by the investment manager and/or any of its affiliates. Absent these fee waivers and/or expense reimbursement arrangements, performance results may have been lower. Please see Note 4, "Fees and Other Transactions With Affiliates" in the Notes to Financial Statements of this report for information on contractual fee waiver and expense reimbursement agreements in place on June 30, 2016, for Columbia Acorn International, Columbia Acorn Select, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund and voluntary fee waiver and expense reimbursement arrangements in place for Columbia Acorn International, Columbia Acorn International Select and Columbia Acorn Select.

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

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

Continued on Page 3.


2



FUND PERFORMANCE VS. BENCHMARKS Class Z Average Annual Total Returns through 6/30/16

Class Z Shares   2nd
quarter*
  Year to
date*
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Columbia Acorn® Fund (ACRNX) (6/10/70)    

2.58

%

   

-0.18

%

   

-7.84

%

   

6.36

%

   

6.27

%

   

14.04

%

 

Russell 2500 Index

   

3.57

%

   

3.98

%

   

-3.67

%

   

9.48

%

   

7.32

%

   

N/A

   

S&P 500 Index**

   

2.46

%

   

3.84

%

   

3.99

%

   

12.10

%

   

7.42

%

   

10.80

%

 
Columbia Acorn International® (ACINX) (9/23/92)    

-1.41

%

   

-1.29

%

   

-7.40

%

   

2.96

%

   

5.13

%

   

10.04

%

 

MSCI ACWI Ex USA SMID Cap Index (Net)

   

-1.32

%

   

-0.31

%

   

-6.13

%

   

1.76

%

   

3.43

%

   

N/A

   

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

   

0.24

%

   

1.98

%

   

-5.35

%

   

2.49

%

   

4.76

%

   

7.86

%

 
Columbia Acorn USA® (AUSAX) (9/4/96)    

7.41

%

   

0.92

%

   

-7.18

%

   

7.24

%

   

6.04

%

   

9.93

%

 

Russell 2000 Index

   

3.79

%

   

2.22

%

   

-6.73

%

   

8.35

%

   

6.20

%

   

7.88

%

 
Columbia Acorn Int'l SelectSM (ACFFX) (11/23/98)    

0.19

%

   

-1.71

%

   

-6.36

%

   

2.07

%

   

4.61

%

   

7.85

%

 

MSCI ACWI Ex USA Index (Net)

   

-0.64

%

   

-1.02

%

   

-10.24

%

   

0.10

%

   

1.87

%

   

N/A

   

S&P Developed Ex-U.S. Between $2B and $10B Index

   

-1.12

%

   

-0.29

%

   

-4.03

%

   

3.58

%

   

3.66

%

   

6.98

%

 
Columbia Acorn SelectSM (ACTWX) (11/23/98)    

-0.89

%

   

-1.21

%

   

-7.28

%

   

5.78

%

   

5.48

%

   

9.27

%

 

S&P MidCap 400 Index

   

3.99

%

   

7.93

%

   

1.33

%

   

10.55

%

   

8.55

%

   

10.01

%

 
Columbia Thermostat FundSM (COTZX) (9/25/02)    

1.81

%

   

3.69

%

   

2.76

%

   

6.46

%

   

6.13

%

   

7.40

%

 

S&P 500 Index

   

2.46

%

   

3.84

%

   

3.99

%

   

12.10

%

   

7.42

%

   

9.29

%

 

Barclays U.S. Aggregate Bond Index

   

2.21

%

   

5.31

%

   

6.00

%

   

3.76

%

   

5.13

%

   

4.59

%

 

50/50 Blended Benchmark

   

2.34

%

   

4.68

%

   

5.25

%

   

8.07

%

   

6.60

%

   

7.20

%

 
Columbia Acorn Emerging Markets FundSM (CEFZX) (8/19/11)    

1.86

%

   

1.27

%

   

-14.52

%

   

     

     

1.72

%

 

MSCI Emerging Markets SMID Cap Index (Net)

   

0.15

%

   

3.21

%

   

-12.19

%

   

     

     

-1.35

%

 

S&P Emerging Markets Between $500M and $5B Index

   

1.96

%

   

6.78

%

   

-10.01

%

   

     

     

0.71

%

 
Columbia Acorn European FundSM (CAEZX) (8/19/11)    

-4.80

%

   

-3.70

%

   

-5.84

%

   

     

     

8.55

%

 

MSCI AC Europe Small Cap Index (Net)

   

-6.71

%

   

-7.52

%

   

-7.58

%

   

     

     

9.66

%

 

S&P Europe Between $500M and $5B Index

   

-6.07

%

   

-7.22

%

   

-7.87

%

   

     

     

9.79

%

 

The inception dates for Class A, B and C shares (if offered) are as follows: Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select, 10/16/00; Columbia Thermostat Fund, 3/3/03; Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 8/19/11. The inception dates for Class I shares are as follows: Columbia Acorn Fund, Columbia Acorn International, Columbia Acorn USA, Columbia Acorn International Select and Columbia Acorn Select, 9/27/10; Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 8/19/11. The inception date for Class R shares for Columbia Acorn International is 8/2/11. The inception date for Class R4, R5 and Y shares (if offered) is as follows: Columbia Acorn Fund, Columbia Acorn USA, Columbia Acorn International Select, Columbia Acorn Select, Columbia Thermostat Fund, Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 11/8/12, except that Class Y shares of Columbia Acorn Emerging Markets Fund commenced operations on 6/13/13 and Class R4 shares of Columbia Acorn European Fund commenced operations on 6/25/14. The inception date for Class R5 shares of Columbia Acorn International is 8/2/11. The inception date for Class R4 and Y shares of Columbia Acorn International is 11/8/12. The inception date for Class Z shares is as follows: Columbia Acorn Fund, 6/10/70; Columbia Acorn International, 9/23/92; Columbia Acorn USA, 9/4/96; Columbia Acorn International Select and Columbia Acorn Select, 11/23/98; Columbia Thermostat Fund, 9/25/02; Columbia Acorn Emerging Markets Fund and Columbia Acorn European Fund, 8/19/11. Class Y shares for Columbia Acorn European Fund are not currently available for purchase.

*Not annualized.

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

Please see Page 1 for a description of the indexes listed above.


3




COLUMBIA ACORN® FUND

IN A NUTSHELL

 

 
P. Zachary Egan
Co-Portfolio Manager
  Fritz Kaegi
Co-Portfolio Manager
 

 
Matthew A. Litfin
Co-Portfolio Manager
 

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

Columbia Acorn Fund Class Z shares gained 2.58% in the second quarter of 2016, compared to a 3.57% gain of the Fund's primary benchmark, the Russell 2500 Index. For the first six months of the year, the Fund posted a slight loss of 0.18%, while the benchmark gained 3.98%. During the second quarter, U.S. small-cap stocks outpaced global equities, as smaller U.S. companies were aided by their lower sensitivity to both a rising U.S. dollar and concerns about the potential fallout from the Brexit vote.

The Fund's relative performance in the quarter was negatively impacted by its overweight in the transportation and biotech industries, and its long-standing underweight in real estate investment trusts and utilities during a quarter in which a global search for yield fueled dividend-paying stocks. The more growth-oriented, profitable names that the Fund typically owns were out of favor in the second quarter, as value continued to outperform growth, as it did year to date. While these market shifts were not ideal for our growth-at-a reasonable-price approach, market leadership ebbs and flows over time, and we were pleased to see that, while sector allocation detracted from overall performance, strong stock selection added over 100 basis points to Fund returns in the quarter. We view this as confirmation that our recent repositioning efforts are taking the Fund in the right direction. We added 22 new positions in the second quarter and sold 20 names. We continue to move away from lower-conviction, sub-scale positions, and toward meaningful exposure to higher-quality names that we believe have significant future growth potential and strong prospects for outsized return on capital profiles.

The Fund's top two contributors to performance in the second quarter were IT stocks that had strong gains on acquisition news. Demandware, an e-commerce website platform for retailers, gained 91% after agreeing to be acquired by Salesforce.com. Cvent, a provider of software used by corporate event planners and hotels, saw its stock rise 60% following the announcement of its agreement to be acquired by Vista Equity Partners. We sold both positions, capturing nice gains for the Fund.

We shifted assets toward health care equipment names, increasing the Fund's overweight in the health care sector. We believe this area of the health care industry offers solid growth potential through companies with good reinvestment possibilities and high rates of return. We also increased the Fund's exposure to diversified financial services companies in the quarter, although the market has punished companies like Lazard and Jones Lang

LaSalle for a slowdown in transaction-oriented business. These holdings were the top two detractors from performance in the quarter, with Lazard, a provider of corporate advisory and asset management services, falling 22% and Jones Lang LaSalle, a provider of real estate services, declining 17%. We took advantage of the declines to add to both positions in the first half of the year, as we believe both companies are high-quality franchises with strong long-term outlooks.

We are excited about the potential that we feel exists in the Fund's newly repositioned portfolio. Looking at trailing three-year weighted average earnings per share (EPS) growth in the portfolio at quarter end, the portfolio showed EPS growth of 18%, which is significantly higher than the benchmark's 10%. Last year at this time, the same number was 12% for the Fund, so we have tilted the portfolio toward faster growers. Our renewed emphasis on high-quality growth names in the Fund has led us to companies that we believe not only have high rates of return, but that are industry leaders with consistent long-term performance, future growth potential, and that have the ability to reinvest new capital at above-average rates of return.

†The Russell 2500 Index gained 3.57% in the second quarter, which compares to a 2.46% return for the U.S. large-cap S&P 500 Index and a 1.46% decline of the MSCI EAFE Index (Net), a measure of large-cap international equity performance. The S&P Global Ex-U.S. Small Cap Index, which is made up of the bottom 20% of institutionally investable capital outside the United States, was down 0.69% in the second quarter.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


4



COLUMBIA ACORN® FUND

AT A GLANCE

Total Net Assets of the Fund:
$5.7 billion

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

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

June 10, 1970 (Fund inception) through June 30, 2016

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

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Class Z (6/10/70 inception)    

2.58

%

   

-0.18

%

   

-7.84

%

   

6.36

%

   

6.27

%

   

14.04

%

 
Class A (10/16/00 inception)  

without sales charge

   

2.47

     

-0.37

     

-8.16

     

6.05

     

5.96

     

13.67

   

with sales charge

   

-3.44

     

-6.13

     

-13.44

     

4.80

     

5.34

     

13.53

   

Russell 2500 Index*

   

3.57

     

3.98

     

-3.67

     

9.48

     

7.32

     

N/A

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 0.82% for Class Z shares and 1.07% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit investor.columbiathreadneedle.com/us/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  Align Technology
Invisalign System to Correct Malocclusion
(Crooked Teeth)
  2.6

%

 

2.

  EdR
Student Housing
  1.6

%

 

3.

  Expeditors International of Washington
International Freight Forwarder
  1.6

%

 

4.

  Vail Resorts
Ski Resort Operator & Developer
  1.5

%

 

5.

  VWR
Distributor of Lab Supplies
  1.4

%

 

6.

  Robert Half International
Temporary & Permanent Staffing in Finance,
Accounting & Other Professions
  1.4

%

 

7.

  HealthSouth
Inpatient Rehabilitation Facilities &
Home Health Care
  1.3

%

 

8.

  Acuity Brands
Commercial Lighting Fixtures
  1.2

%

 

9.

  Lazard
Corporate Advisory & Asset Management
  1.2

%

 

10.

  Toro
Turf Maintenance Equipment
  1.2

%

 

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


5



COLUMBIA ACORN INTERNATIONAL®

IN A NUTSHELL

 

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

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

Columbia Acorn International Class Z shares ended the second quarter down 1.41%, performing in line with the Fund's primary benchmark, the MSCI ACWI Ex USA SMID Cap Index (Net), which was down 1.32%. For the semiannual period, the Fund declined 1.29% versus a 0.31% drop for the benchmark. Major factors impacting markets in the quarter were the surprise outcome of the Brexit vote in the United Kingdom, continued strong performance from the commodities sector, and signs of strength in a number of developing economies, particularly in Southeast Asia.

As discussed in our letter at the front of this report, the United Kingdom's decision to exit the European Union was somewhat unexpected by global markets and triggered a short-term flight to safety as investors considered the potential consequences of this action. The immediate reaction was a rise in the U.S. dollar and the Japanese yen, while the UK pound fell to its lowest levels in the last 30 years. Renewed discussions of a prolonged low interest rate environment in most developed economies provided a positive jolt to many emerging markets with economies sensitive to global rates. While the Fund declined nearly 9% over the two trading days following the Brexit vote, it regained over half of this drop within a week. As long-term investors, our focus remained on the medium-term impacts this decision could have on Fund holdings, and the adjustments we made to the portfolio were modest. We did exit low-cost airline EasyJet, as we believe Brexit could impair business prospects on a two-year-plus view. Brexit makes it unclear how regulation might bear on EasyJet's ability to operate in and out of the United Kingdom, and also raises concerns about potential constraints on labor mobility, as continental Europeans working in the United Kingdom constitute an important part of EasyJet's customer base. Its stock declined 39% in the quarter. We took advantage of the short-term price volatility around the Brexit vote to add to the Fund's position in Rightmove soon after the quarter end. Rightmove is a UK provider of real estate listings via the Internet, and we struggle to see how Brexit will materially change prospects for the company going forward. In continental Europe, the Fund's long-standing strategic underweight in European banks proved positive, as the uncertainty raised by the referendum weighed heavily on these stocks.

One area that continued to perform well in the second quarter was commodities. Year to date, the energy and basic materials sectors of the benchmark were up over 13% in U.S. dollars (USD). Continued stable economic growth and very low interest rates across developed economies, combined with the positive effects of China's stimulus policies enacted in 2015, have reignited confidence in the underlying price for a number of basic materials. Those emerging markets dependent upon

commodity exports outperformed, but were modest weights within the Fund and benchmark. Year to date within the Fund's small- to mid-cap equity benchmark, Brazil (+49% in USD), Russia (+38% in USD) and South Africa (+20% in USD) all rallied with strengthening currencies after mostly dismal 2015 performance. Tahoe Resources, a low-cost silver miner based in Guatemala, was the Fund's top contributor to performance, rising 50% in the quarter on the rebound in silver prices.

Current political uncertainty appears likely to drive a continuation of loose monetary policy in Japan and Europe for the near term. The low interest rate environment is fueling a global search for yield, buoying the prices of stable, cash-generative and dividend-paying stocks. Unprecedented intervention to keep interest rates low will eventually reverse, which we believe will make current valuations assigned to these "safe haven" securities hard to justify, particularly where there is little earnings growth. Accordingly, we have worked hard over recent quarters to increase the Fund's exposure to companies with solid earnings growth. We expect these businesses to prove more resilient should interest rates normalize. If this mean reversion takes longer than expected, this will likely be because of ongoing weak demand globally, in which case companies with growing earnings should command a valuation premium, also not a bad outcome for long-term growth investors. New Fund positions that reflect this focus on growth include DIP, an operator of online websites and mobile applications for temporary job listings in Japan. DIP is capitalizing on an aging Japanese population that is driving a labor shortage; a corporate preference for temporary workers to maintain flexibility and curb costs; and increased user preference for Internet and mobile job listings. Since 2009, full-time workers in Japan have declined by 2.35 million, while part-time jobs have increased by 1.17 million. Another new idea during the first half of 2016 was Actelion, a Swiss-based biopharmaceutical company focused on the discovery, development and commercialization of drugs for orphan diseases. Actelion is in the early innings of what we believe to be a strong and sustainable growth cycle fueled by two new drug therapies that are rapidly gaining share in the $5 billion-plus pulmonary hypertension market.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


6



COLUMBIA ACORN INTERNATIONAL®

AT A GLANCE

Total Net Assets of the Fund:
$5.7 billion

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

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

September 23, 1992 (Fund inception) through June 30, 2016

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period. A $10,000 investment in Columbia Acorn International at inception appreciated to $15,870 on May 31, 1994, the inception date of the MSCI ACWI Ex USA SMID Cap Index (Net). For comparison with the MSCI ACWI Ex USA SMID Cap Index (Net), we assigned the index the same value as the Fund at index inception.

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Class Z (9/23/92 inception)    

-1.41

%

   

-1.29

%

   

-7.40

%

   

2.96

%

   

5.13

%

   

10.04

%

 
Class A (10/16/00 inception)  

without sales charge

   

-1.47

     

-1.42

     

-7.65

     

2.65

     

4.79

     

9.63

   

with sales charge

   

-7.14

     

-7.08

     

-12.96

     

1.44

     

4.17

     

9.35

   
MSCI ACWI Ex USA SMID Cap
Index (Net)*
   

-1.32

     

-0.31

     

-6.13

     

1.76

     

3.43

     

N/A

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

0.24

     

1.98

     

-5.35

     

2.49

     

4.76

     

7.86

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark effective January 1, 2016. Prior to January 1, 2016, the S&P Global Ex-U.S. Between $500M and $5B Index was the Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 0.99% for Class Z shares and 1.24% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit investor.columbiathreadneedle.com/us/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  Novozymes (Denmark)
Industrial Enzymes
  2.4

%

 
2.   CCL Industries (Canada)
Global Label Converter
  2.1

%

 

3.

  Wirecard (Germany)
Online Payment Processing & Risk Management
  1.6

%

 

4.

  Hexagon (Sweden)
Design, Measurement & Visualization
Software & Equipment
  1.5

%

 

5.

  Partners Group (Switzerland)
Private Markets Asset Management
  1.5

%

 

6.

  Domino's Pizza Enterprise (Australia)
Domino's Pizza Operator in Australia & New Zealand
  1.4

%

 

7.

  Trelleborg (Sweden)
Manufacturer of Sealing, Dampening &
Protective Solutions for Industry
  1.4

%

 

8.

  Halma (United Kingdom)
Health & Safety Sensor Technology
  1.4

%

 

9.

  Rightmove (United Kingdom)
Internet Real Estate Listings
  1.3

%

 

10.

  Recruit Holdings (Japan)
Recruitment & Media Services
  1.3

%

 

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


7



COLUMBIA ACORN USA®

IN A NUTSHELL

 

 
Matthew A. Litfin
Lead Portfolio Manager
  William J. Doyle
Co-Portfolio Manager
 

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies. The Fund may invest significantly in issuers within a particular sector, which may be negatively affected by market, economic or other conditions, making the Fund more vulnerable to unfavorable developments in the sector.

Columbia Acorn USA Class Z shares gained 7.41% in the second quarter of 2016, strongly outperforming the 3.79% gain of the Fund's primary benchmark, the Russell 2000 Index. The quarter's large lead over its benchmark was the result of strong individual stock performance across nearly all industry sectors. Year to date, the Fund's 0.92% gain was behind the benchmark's 2.22% return. Value stocks outpaced growth stocks during the semiannual period, holding back the relative performance of the Fund's growth-oriented portfolio.

Our analysts have been working hard for Fund shareholders and we have, in recent months, found many new opportunities to add higher-quality names to the Fund's portfolio. As noted above, our efforts paid off in the second quarter, as strong stock selection drove the Fund's performance more than three full percentage points above the benchmark's positive return. When we looked at the stock selection portion of Columbia Acorn USA's performance, we found that our analyst team had its best stock-picking quarter of the past decade in the second quarter for the Fund. We believe the portfolio that we established (and that we will continue to monitor and strive to improve upon) in the first half of 2016 should allow us to focus even more tightly on value creation and risk-adjusted performance for shareholders.

On an industry and sector basis in the quarter, real estate investment trusts (REITs) and utilities were strong performers within the benchmark, as investors went searching for yield. Material stocks were also strong in the Russell 2000, benefiting from the quarter's recovery in commodity prices. The Fund's underweight in these sectors detracted from performance; however, its overweight positions in the health care and information technology (IT) sectors contributed to relative outperformance in the quarter. The Fund has little exposure to REITs and utilities because many do not fit its growth-oriented style.

Within the IT sector in the Fund, Demandware, an e-commerce website platform for retailers and apparel manufacturers, and Cvent, a developer of software used by corporate event planners and hotels, gained 91% and 65% during the quarter, respectively, both on acquisition news. Demandware agreed to be acquired by Salesforce.com, and Cvent announced it was to be acquired by Vista Equity Partners. We sold both positions on the news. SPS Commerce, a provider of supply chain management software, was a large detractor in the first quarter but rebounded in the second, gaining 41%, as previous concerns related to a temporary disruption in its sales force abated.

The Fund participated in the June 23, 2016, initial public offering (IPO) of Twilio, a business software company offering an in-application communications software platform. Our analysis of the stock suggested the company had a competitive advantage in its market niche and would enjoy strong revenue growth for the long term. The market agreed with our assessment, and the stock rose dramatically following the IPO, gaining 139% in just one week. Applying our valuation discipline, we sold the position.

On the downside, Fiesta Restaurant Group, an owner/operator of two restaurant chains, was the top detractor in the quarter, falling 34%. The company experienced a slower start to the year, but we believe significant opportunity remains to expand its high-volume and differentiated Pollo Tropical restaurants. Virtu Financial, a high-speed trader, was also among the detractors, declining 18% in the quarter on disappointing year-over-year results. IPG Photonics fell 17% in the quarter; while IPG's position in fiber lasers remains solid, the company cut its outlook for 2016 due to weak demand from auto-related customers in Japan and on currency concerns. We will continue to monitor the performance of these companies and their stocks.

During the second quarter, Fund shareholders enjoyed the benefits of some of the repositioning that we implemented earlier in the year. We believe the companies that Columbia Acorn USA holds have strong prospects for solid earnings growth and stock price performance as we move into the second half of the year. Applying our time-tested valuation discipline, we will continue to scour the landscape to find the very best small-cap companies across industries.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


8



COLUMBIA ACORN USA®

AT A GLANCE

Total Net Assets of the Fund:
$679.3 million

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

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

September 4, 1996 (Fund inception) through June 30, 2016

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

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Class Z (9/4/96 inception)    

7.41

%

   

0.92

%

   

-7.18

%

   

7.24

%

   

6.04

%

   

9.93

%

 
Class A (10/16/00 inception)  

without sales charge

   

7.40

     

0.82

     

-7.40

     

6.97

     

5.75

     

9.57

   

with sales charge

   

1.22

     

-5.00

     

-12.72

     

5.72

     

5.13

     

9.24

   

Russell 2000 Index*

   

3.79

     

2.22

     

-6.73

     

8.35

     

6.20

     

7.88

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 1.18% for Class Z shares and 1.43% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit investor.columbiathreadneedle.com/us/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  Toro
Turf Maintenance Equipment
  2.4

%

 

2.

  Drew Industries
RV & Manufactured Home Components
  2.1

%

 

3.

  VWR
Distributor of Lab Supplies
  1.9

%

 

4.

  Papa John's International
Franchisor of Pizza Restaurants
  1.9

%

 

5.

  HealthSouth
Inpatient Rehabilitation Facilities & Home
Health Care
  1.8

%

 

6.

  MarketAxess
Bond Exchange
  1.8

%

 

7.

  Medidata Solutions
Cloud-based Software for Drug Studies
  1.8

%

 

8.

  UniFirst
Uniform Rental
  1.6

%

 

9.

  CoStar Group
Commercial Real Estate Data Aggregator & Web
Marketing for Retail Landlords
  1.6

%

 

10.

  Ligand Pharmaceuticals
Royalties from Licensing Drug Delivery Technology
  1.6

%

 

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


9



COLUMBIA ACORN INTERNATIONAL SELECTSM

IN A NUTSHELL

 

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

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

Columbia Acorn International Select Class Z shares ended the second quarter of 2016 up 0.19%, while the Fund's primary benchmark, the MSCI ACWI Ex USA Index (Net), fell 0.64%. Year to date through June 30, the Fund was down 1.71% versus a benchmark decline of 1.02%. The Fund's stock performance in the Asia ex Japan region helped to drive outperformance in the second quarter, as did stock selection and a modest overweight in Europe. Not surprising given the Brexit vote results, the Fund's exposure to the United Kingdom and Ireland was the largest regional detractor in the quarter, though we were underweight versus the benchmark in these markets.

On a sector basis, the Fund had strong performance in the information technology (IT) sector, benefiting from both its overweight exposure to the sector and its stock selection. The Fund had a U.S. dollar-adjusted gain of 9% in the IT sector, compared to a benchmark gain of 0.3%. The Fund's overweight in the consumer discretionary sector detracted from relative performance but returns benefited from good stock selection in the sector. We took advantage of weakness in the consumer discretionary sector to add to select, high-quality names that we believe have strong, long-term prospects.

Reflecting the Fund's IT strength, its three top contributors to performance in the quarter were IT names. NetEase.com, a Chinese provider of online gaming services, gained 35%. The company continued to deliver solid gaming revenue growth and improving e-commerce margins in the second quarter after gaining exclusive Chinese operating rights to such blockbuster games as Activision's "Overwatch" and Microsoft's "Minecraft." Wirecard, a German provider of online payment processing risk management services, declined in the first quarter on allegations of criminal misconduct. We did not believe the allegations had merit and added to the Fund's position on the decline. The market echoed our skepticism in the second quarter, driving a 16% rebound in the stock. Taiwan's Largan Precision, a manufacturer of mobile device camera lenses and modules, continued to dominate the high-end miniature lens business used in handsets and mobile devices, expanding its operating margin from 50% to 57% and enjoying a 19% gain in its stock in the quarter.

Other top contributors in the quarter included Japan's Bandai Namco, a maker of branded toys and related content. Up 18% in the quarter, the company continues to leverage its strong toy brands to enter new categories, such as mobile, and geographies beyond Japan. Up 13% in the quarter, KDDI, a mobile and fixed-line communication services provider in Japan, delivered steady growth by improving its average revenue per user, and its outlook remains stable.

On the downside, Eutelsat, a French provider of fixed satellite services, issued a profit warning for the current year, sending its stock down 42% in the quarter. Down 22%, Ryanair, a European low-cost airline based in Ireland, fell on uncertainties created by the Brexit decision. CCL Industries, a Canadian global label converter, was a strong outperformer last year, but so far this year a large rotation in the Canadian market toward energy and basic materials and out of the consumer space has hurt the stock, leading to an 8% decline in the second quarter. Fundamentals remain strong at CCL, and we expect that synergies following its acquisition of Checkpoint Systems will be substantially higher than official guidance. Rightmove, a UK provider of Internet real estate listings, fell 18% in the second quarter, moving sharply downward in the wake of Brexit.

In the second quarter, we saw a continuation of economic uncertainty around the world and increased political nervousness. We expect that there will continue to be uncertainties over the next 18 months, as some of the world's large democracies elect new presidents, and investors reposition portfolios in light of how they expect Brexit to impact different sectors, countries and companies. We have positioned the Fund defensively in the United Kingdom, focusing on companies that stand to benefit from pound weakness and taking advantage of market weakness to build exposure to select, high-quality consumer names. The Fund's more mid-cap focus allows us to fish in a pond where liquidity is high, making it possible for us to trade to take advantage of market volatility.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


10



COLUMBIA ACORN INTERNATIONAL SELECTSM

AT A GLANCE

Total Net Assets of the Fund:
$110.0 million

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

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

November 23, 1998 (Fund inception) through June 30, 2016

This chart shows the change in value of a hypothetical $10,000 investment in Class Z shares of the Fund during the stated time period. A $10,000 investment in Columbia Acorn International Select at inception appreciated to $17,309 on December 31, 2000, the month-end of the inception date of the MSCI ACWI Ex USA Index (Net). For comparison with the MSCI ACWI Ex USA Index (Net), we assigned the index the same value as the Fund at month-end of the index inception date.

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Class Z (11/23/98 inception)    

0.19

%

   

-1.71

%

   

-6.36

%

   

2.07

%

   

4.61

%

   

7.85

%

 
Class A (10/16/00 inception)  

without sales charge

   

0.14

     

-1.88

     

-6.61

     

1.76

     

4.28

     

7.50

   

with sales charge

   

-5.64

     

-7.51

     

-11.98

     

0.57

     

3.66

     

7.14

   

MSCI ACWI Ex USA Index (Net)*

   

-0.64

     

-1.02

     

-10.24

     

0.10

     

1.87

     

N/A

   
S&P Developed Ex-U.S.
Between $2B and $10B Index
   

-1.12

     

-0.29

     

-4.03

     

3.58

     

3.66

     

6.98

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark effective January 1, 2016. Prior to January 1, 2016, the S&P Developed Ex-U.S. Between $2B and $10B Index was the Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 1.15% for Class Z shares and 1.40% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit investor.columbiathreadneedle.com/us/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  Novozymes (Denmark)
Industrial Enzymes
  5.2

%

 

2.

  CCL Industries (Canada)
Global Label Converter
  5.2

%

 

3.

  Partners Group (Switzerland)
Private Markets Asset Management
  4.5

%

 

4.

  Wirecard (Germany)
Online Payment Processing & Risk Management
  4.1

%

 

5.

  Hexagon (Sweden)
Design, Measurement & Visualization
Software & Equipment
  3.5

%

 

6.

  Aeon Mall (Japan)
Suburban Shopping Mall Developer,
Owner & Operator
  3.5

%

 

7.

  Largan Precision (Taiwan)
Mobile Device Camera Lenses & Modules
  3.4

%

 
8.   Amcor (Australia)
Flexible & Rigid Packaging
  3.1

%

 

9.

  NetEase.com (China)
Chinese Online Gaming Services
  3.0

%

 

10.

  Bandai Namco (Japan)
Branded Toys & Related Content
  3.0

%

 

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


11



COLUMBIA ACORN SELECTSM

IN A NUTSHELL

 

 
David L. Frank
Co-Portfolio Manager
  Matthew S. Szafranski
Co-Portfolio Manager
 

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

Columbia Acorn Select Class Z shares ended the second quarter of 2016 down 0.89%, underperforming the 3.99% gain of the Fund's primary benchmark, the S&P MidCap 400 Index. For the first half of the year, the Fund was down 1.21%, while the benchmark gained 7.93%. The Fund's growth-oriented portfolio struggled in an investment environment that favored value during much of the six-month period. In the second quarter, we saw a continuation of the move toward more defensive areas of the market like utility and material stocks, which were top-performing sectors within the benchmark but are significant underweights in the Fund. At the end of the second quarter, the United Kingdom's vote to exit the European Union negatively impacted three Fund holdings with European exposure and detracted approximately 1.5% from Fund performance in the quarter. CWAM's global chief investment officer offers additional thoughts on Brexit at the beginning of this report.

The biggest detractor from performance in the second quarter and year to date was Union Agriculture, a farmland operator in Uruguay. Down 36% in the quarter, we decided to exit the position. For the sixth months ended June 30, this stock was down 55% and detracted 1.5% from performance.

As mentioned, the Fund owned stock in three U.S. companies that were hurt in the quarter by their exposure to Europe and the United Kingdom. Lazard, a provider of corporate advisory and asset management services, ended the quarter down 16%. The company's merger advisory services in Europe are expected to see sharp declines through the rest of 2016, and a strong dollar could negatively impact its asset management business in the near term. Jones Lang LaSalle, a provider of commercial real estate services worldwide, fell 17% on concerns of a decline in commercial real estate transaction and leasing volumes in China. Following the Brexit vote, these concerns expanded to include the United Kingdom and Europe. Liberty Global, a provider of cable TV franchises outside of the United States, fell 14%, as roughly 40% of its revenue is generated in the United Kingdom and the rest is generated in Europe. We do not believe that Brexit has diminished the long-term value of these companies.

Leading performance in the quarter, pizza franchisor Papa John's International gained 26%, as the company proved its ability to drive solid earnings in a promotional pizza environment. Communications towers owner Crown Castle International gained 18% in the quarter. The company benefited from both an increase in mobile data usage and, as a real estate investment trust, from the popularity of dividend-paying stocks among yield-hungry investors.

Nordson, a manufacturer of dispensing systems for adhesives and coatings, ended the quarter up 10%. After experiencing lackluster sales in 2015 like many industrials dependent on overseas revenues, Nordson returned to growth in the first half of 2016, benefiting from launches in new technology like mobile phones that utilize the company's cutting edge dispensing and testing technologies.

While we are disappointed with the Fund's underperformance in the first two quarters of the year, we believe it is important to remember that in a concentrated portfolio like Columbia Acorn Select's returns can fluctuate. As we've reshaped and concentrated the Fund's portfolio in the first half of the year, we have moved away from owning more speculative names, and we have focused on creating a portfolio of our analyst team's current top ideas. Eight of the Fund's 10 largest detractors from performance year to date were sold during the first half of the year, making way for higher-quality, higher-conviction stocks. At June 30, the Fund held 34 names, nearly half of which were added to the portfolio in the first six months of the year. The Fund's tilt toward the consumer discretionary and industrial sectors continues. Most importantly, we have refocused on durable, growth-at-a-reasonable price businesses that we believe will outperform over time.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


12



COLUMBIA ACORN SELECTSM

AT A GLANCE

Total Net Assets of the Fund:
$335.7 million

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

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

November 23, 1998 (Fund inception) through June 30, 2016

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

Average Annual Total Returns for period ended June 30, 2016

  2nd
quarter
  Year to
date
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Class Z (11/23/98 inception)    

-0.89

%

   

-1.21

%

   

-7.28

%

   

5.78

%

   

5.48

%

   

9.27

%

 
Class A (10/16/00 inception)  

without sales charge

   

-0.97

     

-1.32

     

-7.56

     

5.48

     

5.17

     

8.93

   

with sales charge

   

-6.68

     

-7.00

     

-12.86

     

4.24

     

4.55

     

8.56

   

S&P MidCap 400 Index*

   

3.99

     

7.93

     

1.33

     

10.55

     

8.55

     

10.01

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 0.88% for Class Z shares and 1.13% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit investor.columbiathreadneedle.com/us/investment-products/mutual-funds/appended-performance for more information.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  LKQ
Alternative Auto Parts Distribution
  5.2

%

 

2.

  Align Technology
Invisalign System to Correct Malocclusion
(Crooked Teeth)
  4.4

%

 

3.

  SVB Financial Group
Bank to Venture Capitalists
  4.3

%

 

4.

  HRG Group
Holding Company
  4.1

%

 

5.

  HealthSouth
Inpatient Rehabilitation Facilities & Home
Health Care
  4.1

%

 

6.

  Amerco
North American Moving & Storage
  4.1

%

 

7.

  Papa John's International
Franchisor of Pizza Restaurants
  3.9

%

 

8.

  Crown Castle International
Communications Towers
  3.8

%

 

9.

  EdR
Student Housing
  3.8

%

 

10.

  Nordson
Dispensing Systems for Adhesives & Coatings
  3.5

%

 

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


13



COLUMBIA THERMOSTAT FUNDSM

IN A NUTSHELL

 

 
David L. Frank
Co-Portfolio Manager
  Christopher J. Olson
Co-Portfolio Manager
 

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

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

Class Z shares of Columbia Thermostat Fund, our fund of funds, ended the second quarter of 2016 up 1.81%. This compares to a 2.46% gain of the Fund's primary equity benchmark, the S&P 500 Index, and a 2.21% gain of the Fund's primary debt benchmark, the Barclays U.S. Aggregate Bond Index. The Fund's custom 50/50 Blended Benchmark gained 2.34% in the quarter. For the first half of the year, the Fund was up 3.69%, which compares to an S&P 500 return of 3.84%, a 5.31% gain of the Barclays index, and a 4.68% return of the Fund's custom blended benchmark.

The Fund's equity portfolio had a weighted average gain of 1.68% in the second quarter. Columbia Select Large Cap Growth Fund led equity gains, increasing 5.28% in the quarter. The weighted average gain for the bond portion of the Fund was 1.97%, with Columbia Total Return Bond Fund offering the top return of 2.95%.

The Fund hit three reallocation triggers in the second quarter. Buying equities when the market declined and selling them when the market rose, the Fund decreased exposure to its stock funds in April and June and increased its exposure in May.

As we mentioned last quarter, following our periodic review of underlying funds called for by Columbia Thermostat Fund's prospectus, we made several changes that were implemented on May 1, 2016. Columbia Income Opportunities Fund now has a 10% weight in the bond portfolio, down from 20%. Columbia U.S. Treasury Index Fund, a U.S. Treasury notes/bonds fund, was added to the bond portfolio with a 10% weight in the portfolio. We also adjusted the stock/bond allocation table levels up by 25 points.

So far in 2016, we have witnessed the remarkable, ongoing strength of longer duration bonds, especially U.S. Treasuries. At the same time, there has been a persistent choppiness in equity markets—early in the year due to worries over a slowdown in the United States as well as emerging markets economies, and then later on concerns about a slowdown in Europe following the Brexit vote. Given Columbia Thermostat Fund's ability to move money into and out of equities, the current volatile equity market environment caters to the Fund's investment style.

Results of the Underlying Funds Owned in Columbia Thermostat Fund

as of June 30, 2016

Stock Funds

Fund   Weightings
in category
  2nd quarter
performance
  Year-to-date
performance
 
Columbia Acorn
International, Class I
   

20

%

   

-1.41

%

   

-1.24

%

 
Columbia Contrarian
Core Fund, Class I
   

20

%

   

1.75

%

   

2.38

%

 
Columbia Dividend
Income Fund, Class I
   

20

%

   

3.92

%

   

7.40

%

 
Columbia Acorn Fund,
Class I
   

10

%

   

2.56

%

   

-0.18

%

 
Columbia Acorn Select,
Class I
   

10

%

   

-0.81

%

   

-1.13

%

 
Columbia Large Cap
Enhanced Core Fund,
Class I
   

10

%

   

1.25

%

   

1.64

%

 
Columbia Select
Large Cap Growth Fund,
Class I
   

10

%

   

5.28

%

   

-7.03

%

 
Weighted Average
Equity Gain
   

100

%

   

1.68

%

   

1.05

%

 

Bond Funds

Fund   Weightings
in category
  2nd quarter
performance
  Year-to-date
performance
 
Columbia Short Term
Bond Fund, Class I
   

40

%

   

0.84

%

   

1.86

%

 
Columbia Total Return
Bond Fund, Class I
   

20

%

   

2.95

%

   

5.96

%

 
Columbia U.S. Government
Mortgage Fund, Class I
   

20

%

   

1.73

%

   

3.14

%

 
Columbia Income
Opportunities Fund,
Class I
   

10

%*

   

2.57

%

   

5.41

%

 
Columbia U.S. Treasury
Index Fund, Class I
   

10

%*

   

2.02

%

   

5.25

%

 
Weighted Average
Income Gain
   

100

%

   

1.97

%

   

3.83

%

 

*Changed effective May 1, 2016. Weighted average returns through the end of the period reflect linked returns between the previous fund weightings and the current weights in these positions.

Columbia Thermostat Fund Rebalancing in the Second Quarter

April 14, 2016

 

20% stocks, 80% bonds

 

May 16, 2016

 

25% stocks, 75% bonds

 

June 24, 2016

 

20% stocks, 80% bonds

 

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


14



COLUMBIA THERMOSTAT FUNDSM

AT A GLANCE

Total Net Assets of the Fund:
$1.2 billion

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

The Growth of a $10,000 Investment in Columbia Thermostat FundSM Class Z Shares

September 25, 2002 (Fund inception) through June 30, 2016

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

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

 

5 years

 

10 years

  Life of
Fund
 
Class Z (9/25/02 inception)    

1.81

%

   

3.69

%

   

2.76

%

   

6.46

%

   

6.13

%

   

7.40

%

 
Class A (3/3/03 inception)  

without sales charge

   

1.79

     

3.57

     

2.53

     

6.21

     

5.88

     

7.13

   

with sales charge

   

-4.07

     

-2.37

     

-3.37

     

4.96

     

5.25

     

6.67

   

S&P 500 Index*

   

2.46

     

3.84

     

3.99

     

12.10

     

7.42

     

9.29

   
Barclays U.S. Aggregate
Bond Index*
   

2.21

     

5.31

     

6.00

     

3.76

     

5.13

     

4.59

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmarks. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 0.77% for Class Z shares and 1.02% for Class A shares. The returns shown for periods prior to the inception of the Fund's Class A shares append the returns of the Fund's Class Z shares, the Fund's oldest share class. These returns are adjusted to reflect any higher class-related operating expenses of the newer share classes, as applicable. Please visit investor.columbiathreadneedle.com/us/investment-products/mutual-funds/appended-performance for more information.

Asset Allocation

as a percentage of net assets, as of 6/30/16

Portfolio Weightings

as a percentage of assets in each investment category, as of 6/30/16

Stock Mutual Funds

Columbia Acorn International, Class I

   

20

%

 

Columbia Contrarian Core Fund, Class I

   

20

%

 

Columbia Dividend Income Fund, Class I

   

20

%

 

Columbia Acorn Fund, Class I

   

10

%

 

Columbia Acorn Select, Class I

   

10

%

 
Columbia Large Cap Enhanced Core Fund,
Class I
   

10

%

 
Columbia Select Large Cap Growth Fund,
Class I
   

10

%

 

Bond Mutual Funds

Columbia Short Term Bond Fund, Class I

   

40

%

 

Columbia Total Return Bond Fund, Class I

   

20

%

 
Columbia U.S. Government Mortgage Fund,
Class I
   

20

%

 
Columbia Income Opportunities Fund,
Class I
   

10

%

 

Columbia U.S. Treasury Index Fund, Class I

   

10

%

 


15



COLUMBIA ACORN EMERGING MARKETS FUNDSM

IN A NUTSHELL

 

 
Fritz Kaegi
Co-Portfolio Manager
  Stephen Kusmierczak
Co-Portfolio Manager
 

 

 
Louis J. Mendes
Co-Portfolio Manager
  Satoshi Matsunaga
Co-Portfolio Manager
 

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

Columbia Acorn Emerging Markets Fund Class Z shares gained 1.86% in the second quarter of 2016, outperforming the 0.15% return of the Fund's primary benchmark, the MSCI Emerging Markets SMID Cap Index (Net). Year to date through June 30, the Fund was up 1.27%, which compares to a 3.21% gain for the benchmark. During the second quarter, the Fund benefited from its large overweight in Southeast Asia and from our stock selection in this region. Good stock selection in the consumer discretionary sector also bolstered relative returns. For the year-to-date period, Fund performance relative to the benchmark was hurt by poor stock performance in China and India. There has been a significant divergence in performance between the more developing end of the emerging markets and the large continental economies of China and India, as the smaller, more developing markets have outperformed so far in 2016 on strengthening local currencies and a rebound in commodity prices.

On June 24, 2016, the Brexit bombshell hit the markets. Investors' initial reaction was to sell riskier assets, including emerging market equities, but, within a week, the Fund's benchmark closed above pre-Brexit levels. In contrast to the political uncertainties being felt in much of the developed world, the election of Rodrigo Duterte in the Philippines sparked a post-election rally in that country on hopes that the new president will implement needed infrastructure projects and tap into growth potential within the country. The Fund benefited from the rally and from our strong stock picking in this market, as Fund holdings in the Philippines provided a U.S. dollar-adjusted gain of 22% compared to an 8% gain in the benchmark for the quarter. The Fund also benefited from economic policies implemented by reform-oriented political leadership in Indonesia, where the Fund has a significant overweight relative to the benchmark and also outperformed in the second quarter.

We have maintained an emphasis in the Fund on companies benefiting from the rising aspirations and incomes of a growing middle class. This theme is behind the Fund's long-standing overweight in the consumer discretionary sector, which was the top-performing sector in the Fund in the second quarter. Four of the Fund's five top contributors to performance in the quarter were consumer discretionary stocks. Melco Crown (Philippines) Resorts, an integrated resort operator in Manila, declined last year on negative sentiment toward gaming in China. During the second quarter, the market took note of the company's solid fundamentals and its more domestic-driven business, leading to a 48% gain in the stock. Up 16%, Zee Entertainment Enterprises, an Indian

programmer of pay TV content, rebounded from a first-quarter drop, benefiting from positive growth expectations. Tahoe Resources, a silver and gold miner in Guatemala, Canada and Peru, gained 51% on the back of significant increases in silver and gold prices. Xinhua Winshare Publishing, a Sichuan publisher, distributor and retailer, reported good results and also announced that officials approved its application to list on China's A-share market. Its stock gained 25% in the quarter.

On the downside, Sihuan Pharmaceutical Holdings Group, a Chinese generic drug manufacturer, was the biggest detractor during the second quarter and for the half year. Down 30% in the second quarter, the company was negatively impacted by a slowdown in health care spending in China and increasing price competition in the pharmaceutical industry. Going against the upward trend of the Fund's consumer discretionary holdings, Hoteles City Express, the leading budget hotel operator in Mexico, declined 19% in the quarter despite reporting positive year-over-year results. Adani Ports & Special Economic Zone, an Indian port operator, fell 19% on mixed first quarter results.

While growth rates have decelerated in most developed markets around the world, many emerging markets are offering accelerating growth in evolving and strengthening markets. We believe that emerging market economies benefiting from strong domestic demand fueled by reform-oriented political leadership—countries like the Philippines, India and Indonesia—offer distinct advantages and have minimal exposure to the political uncertainty in Europe and beyond. Over the long term, we believe the Fund should benefit from investing in high-quality businesses with good growth prospects at reasonable valuations, which can be found within our emerging market universe.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


16



COLUMBIA ACORN EMERGING MARKETS FUNDSM

AT A GLANCE

Total Net Assets of the Fund:
$158.7 million

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

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

August 19, 2011 (Fund inception) through June 30, 2016

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

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

  Life of
Fund
 
Class Z (8/19/11 inception)    

1.86

%

   

1.27

%

   

-14.52

%

   

1.72

%

 
Class A (8/19/11 inception)                  

without sales charge

   

1.77

     

1.17

     

-14.75

     

1.44

   

with sales charge

   

-4.07

     

-4.60

     

-19.63

     

0.21

   
MSCI Emerging Markets
SMID Cap Index (Net)*
   

0.15

     

3.21

     

-12.19

     

-1.35

   
S&P Emerging Markets Between
$500M and $5B Index
   

1.96

     

6.78

     

-10.01

     

0.71

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark effective January 1, 2016. Prior to January 1, 2016, the S&P Emerging Markets Between $500M and $5B Index was the Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 1.55% for Class Z shares and 1.80% for Class A shares.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  Zee Entertainment Enterprises (India)
Indian Programmer of Pay Television Content
  4.0

%

 
2.   Media Nusantara Citra (Indonesia)
Media Company in Indonesia
  3.5

%

 

3.

  Samui Airport Property Fund (Thailand)
Thai Airport Operator
  2.7

%

 

4.

  ModeTour Network (Korea)
Travel Services
  2.7

%

 

5.

  Grupo Aeroportuario del Sureste - ADR
(Mexico)
Mexican Airport Operator
  2.6

%

 

6.

  Koh Young Technology (Korea)
Inspection Systems for Printed Circuit Boards
  2.6

%

 

7.

  Link Net (Indonesia)
Fixed Broadband & CATV Service Provider
  2.6

%

 

8.

  Commercial International Bank of
Egypt (Egypt)
Private Universal Bank in Egypt
  2.3

%

 

9.

  Tikkurila (Finland)
Decorative & Industrial Paint in Scandinavia,
Central & Eastern Europe
  2.3

%

 

10.

  NewOcean Energy (China)
Southern China Liquefied Petroleum
Gas Distributor
  2.3

%

 

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


17



COLUMBIA ACORN EUROPEAN FUNDSM

IN A NUTSHELL

 

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

Market risk may affect a single issuer, sector of the economy, industry or the market as a whole. International investing involves certain risks and volatility due to potential political, economic or currency instabilities and different, potentially less stringent, financial and accounting standards than those generally applicable to U.S. issuers. Investments in small- and mid-cap companies involve risks and volatility and possible illiquidity greater than investments in larger, more established companies.

Columbia Acorn European Fund Class Z shares fell 4.80% in the second quarter of 2016, while the Fund's primary benchmark, the MSCI AC Europe Small Cap Index (Net), dropped 6.71%. The Fund also performed better than the benchmark year to date through June 30, falling 3.70% compared to the benchmark's decline of 7.52%. For both periods, the Fund's performance was helped by good relative results in the Mediterranean region, which includes France, Greece, Italy, Portugal and Spain. The Fund's outperformance in this region was largely tied to our underweight and stock selection in the financials sector, where we have focused on brokerage, asset management and real estate names and away from European banks. As we've noted previously, we are skeptical about the long-term health of European banks, particularly those in Italy, and our concern has been shared by the market in recent quarters.

The June 23, 2016, vote by the United Kingdom to exit the European Union was a significant event in the second quarter. The economic implications for the United Kingdom and the European Union are potentially vast and will take years to address. In the aftermath of the vote, we have already seen the British pound decline to its lowest level in decades, while the Bank of England predicts a decline in GDP and rise in unemployment tied to Brexit. CWAM's global chief investment officer's thoughts on Brexit are presented in a more extensive letter at the beginning of this quarterly report.

Columbia Acorn European Fund was underweight the United Kingdom versus the benchmark going into the vote and did benefit slightly from this positioning. This underweight was the result of our bottom up, fundamental analysis on UK companies and relative valuations, not a prediction on the Brexit vote. We did, however, take advantage of the volatility caused by the Brexit debate prior to the vote to add to positions like Rightmove, a UK Internet real estate listing site, and WH Smith, a newsprint, book and general stationary retailer. While both stocks ended the quarter among the Fund's worst detractors, we don't see a meaningful, long-term impairment of their businesses due to Brexit. The Fund's one UK sale in the quarter was natural sweetener manufacturer PureCircle, which fell 27% in the quarter on concerns unrelated to the referendum results.

Despite the volatile macroeconomic climate in the United Kingdom, Abcam, a UK company that sells antibodies online, ended the quarter up 21% and was the third largest contributor to Fund performance. Abcam actually benefits from a weaker pound, as only 4% of its revenues are generated in the United Kingdom but 20% of its costs are incurred there. During the second quarter, the company

also reported strong growth of 18% driven by business in China and its proprietary solution, Rabmab. News that a competitor had its license suspended also supported Abcam's stock. Another top-contributing name was Wirecard, an online payment processing and risk management company based in Germany, which gained 16% in the quarter. Allegations against Wirecard published earlier in the year caused a first-quarter downturn in the stock. Further investigation—both our own and by the broader market—contradicted the report and led to an uptick in the stock in the second quarter. We added to Wirecard on the decline and were pleased to see our conviction in the stock echoed by the broader market in the second quarter.

We believe that macroeconomic and political risks have increased in Europe, and we expect two important outcomes to follow. First, there will be a continuation of low interest rate policies. The Bank of England and the European Central Bank both held interest rates at current, record-low levels at their meetings following the quarter end. This lower-for-longer environment could help support high valuations in equity markets. Second, there appears to be at least a temporary decline in anti-EU sentiment. Following the Brexit vote and the resulting sharp, negative market reaction, continental European populist parties promoting an EU exit saw their support in polls decline. This shift was apparent in the results of the June 26 elections in Spain and in polling conducted in Germany, France and the Netherlands. Furthermore, outcomes of French and Italian elections in 2017 will provide indications of the direction Europe is likely to take without the United Kingdom. The path of the UK's exit from the EU will be tedious and complicated, and the long-term impacts difficult to assess. Our focus will continue to be on identifying companies that can outgrow their peers in most economic conditions and offer good value to long-term investors.

Fund holdings are as of the date given, are subject to change at any time, and are not recommendations to buy or sell any security.


18



COLUMBIA ACORN EUROPEAN FUNDSM

AT A GLANCE

Total Net Assets of the Fund:
$58.2 million

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

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

August 19, 2011 (Fund inception) through June 30, 2016

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

Average Annual Total Returns for period ended June 30, 2016

    2nd
quarter
  Year to
date
 

1 year

  Life of
Fund
 
Class Z (8/19/11 inception)    

-4.80

%

   

-3.70

%

   

-5.84

%

   

8.55

%

 
Class A (8/19/11 inception)                  

without sales charge

   

-4.87

     

-3.84

     

-6.08

     

8.27

   

with sales charge

   

-10.34

     

-9.37

     

-11.49

     

6.96

   

MSCI AC Europe Small Cap Index (Net)*

   

-6.71

     

-7.52

     

-7.58

     

9.66

   
S&P Europe Between $500M and
$5B Index
   

-6.07

     

-7.22

     

-7.87

     

9.79

   

Results for other share classes can be found on Page 2.

*The Fund's primary benchmark effective January 1, 2016. Prior to January 1, 2016, the S&P Europe Between $500M and $5B Index was the Fund's primary benchmark. Please see Page 1 for index descriptions.

Returns for Class A shown with and without the maximum initial sales charge of 5.75%. As stated in the May 1, 2016, prospectus, as supplemented June 27, 2016, the Fund's annual operating expense ratio is 1.51% for Class Z shares and 1.76% for Class A shares.

Portfolio Diversification

as a percentage of net assets, as of 6/30/16

Top 10 Holdings

as a percentage of net assets, as of 6/30/16

1.

  Munksjo (Finland)†
Specialty Paper Maker
  3.6

%

 

2.

  Wirecard (Germany)
Online Payment Processing & Risk Management
  3.0

%

 

3.

  Halma (United Kingdom)
Health & Safety Sensor Technology
  3.0

%

 
4.   SimCorp (Denmark)
Software for Investment Managers
  2.6

%

 
5.   Aurelius (Germany)
European Turnaround Investor
  2.5

%

 
6.   Trelleborg (Sweden)
Manufacturer of Sealing, Dampening &
Protective Solutions for Industry
  2.5

%

 
7.   Recipharm (Sweden)
Contract Development Manufacturing Organization
  2.5

%

 
8.   Prosegur (Spain)
Security Guards
  2.4

%

 
9.   Unibet (Sweden)
European Online Gaming Operator
  2.3

%

 
10.   Partners Group (Switzerland)
Private Markets Asset Management
  2.3

%

 
 

†The Fund holds shares traded on both the Swedish and Finnish exchanges.

   

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


19




UNDERSTANDING YOUR EXPENSES

As a shareholder, you incur two types of costs. There are transaction costs, which generally include sales charges on purchases and may include redemption fees. There are also ongoing costs, which generally include management 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 Class A, B, C, I, R, R4, R5, Y and Z shares 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 Fund'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.

January 1, 2016 – June 30, 2016

  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

     

996.30

     

1,019.14

     

5.71

     

5.77

     

1.15

   

Class C

   

1,000.00

     

1,000.00

     

992.60

     

1,015.56

     

9.26

     

9.37

     

1.87

   

Class I

   

1,000.00

     

1,000.00

     

998.20

     

1,020.98

     

3.88

     

3.92

     

0.78

   

Class R4

   

1,000.00

     

1,000.00

     

997.70

     

1,020.04

     

4.82

     

4.87

     

0.97

   

Class R5

   

1,000.00

     

1,000.00

     

998.20

     

1,020.74

     

4.12

     

4.17

     

0.83

   

Class Y

   

1,000.00

     

1,000.00

     

998.20

     

1,020.98

     

3.88

     

3.92

     

0.78

   

Class Z

   

1,000.00

     

1,000.00

     

998.20

     

1,020.69

     

4.17

     

4.22

     

0.84

   


20



UNDERSTANDING YOUR EXPENSES, continued

  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

     

985.80

     

1,018.45

     

6.37

     

6.47

     

1.29

   

Class B

   

1,000.00

     

1,000.00

     

982.20

     

1,014.32

     

10.45

     

10.62

     

2.12

   

Class C

   

1,000.00

     

1,000.00

     

982.10

     

1,014.77

     

10.00

     

10.17

     

2.03

   

Class I

   

1,000.00

     

1,000.00

     

987.60

     

1,020.39

     

4.45

     

4.52

     

0.90

   

Class R

   

1,000.00

     

1,000.00

     

984.00

     

1,016.66

     

8.14

     

8.27

     

1.65

   

Class R4

   

1,000.00

     

1,000.00

     

986.70

     

1,019.39

     

5.43

     

5.52

     

1.10

   

Class R5

   

1,000.00

     

1,000.00

     

987.40

     

1,020.14

     

4.69

     

4.77

     

0.95

   

Class Y

   

1,000.00

     

1,000.00

     

987.70

     

1,020.39

     

4.45

     

4.52

     

0.90

   

Class Z

   

1,000.00

     

1,000.00

     

987.10

     

1,019.89

     

4.94

     

5.02

     

1.00

   

Columbia Acorn USA®

 

Class A

   

1,000.00

     

1,000.00

     

1,008.20

     

1,017.70

     

7.19

     

7.22

     

1.44

   

Class C

   

1,000.00

     

1,000.00

     

1,004.60

     

1,014.22

     

10.67

     

10.72

     

2.14

   

Class I

   

1,000.00

     

1,000.00

     

1,010.10

     

1,019.99

     

4.90

     

4.92

     

0.98

   

Class R4

   

1,000.00

     

1,000.00

     

1,009.00

     

1,018.80

     

6.09

     

6.12

     

1.22

   

Class R5

   

1,000.00

     

1,000.00

     

1,009.40

     

1,019.49

     

5.40

     

5.42

     

1.08

   

Class Y

   

1,000.00

     

1,000.00

     

1,010.30

     

1,019.69

     

5.20

     

5.22

     

1.04

   

Class Z

   

1,000.00

     

1,000.00

     

1,009.20

     

1,018.95

     

5.94

     

5.97

     

1.19

   

Columbia Acorn International SelectSM

 

Class A

   

1,000.00

     

1,000.00

     

981.20

     

1,016.61

     

8.18

     

8.32

     

1.66

   

Class C

   

1,000.00

     

1,000.00

     

977.50

     

1,012.68

     

12.05

     

12.26

     

2.45

   

Class I

   

1,000.00

     

1,000.00

     

983.80

     

1,018.95

     

5.87

     

5.97

     

1.19

   

Class R4

   

1,000.00

     

1,000.00

     

982.50

     

1,017.90

     

6.90

     

7.02

     

1.40

   

Class R5

   

1,000.00

     

1,000.00

     

983.00

     

1,018.45

     

6.36

     

6.47

     

1.29

   

Class Y

   

1,000.00

     

1,000.00

     

983.00

     

1,018.70

     

6.11

     

6.22

     

1.24

   

Class Z

   

1,000.00

     

1,000.00

     

982.90

     

1,018.10

     

6.71

     

6.82

     

1.36

   

Columbia Acorn SelectSM

 

Class A

   

1,000.00

     

1,000.00

     

986.80

     

1,018.85

     

5.98

     

6.07

     

1.21

   

Class C

   

1,000.00

     

1,000.00

     

982.30

     

1,015.22

     

9.56

     

9.72

     

1.94

   

Class I

   

1,000.00

     

1,000.00

     

988.70

     

1,020.79

     

4.05

     

4.12

     

0.82

   

Class R4

   

1,000.00

     

1,000.00

     

988.30

     

1,019.99

     

4.84

     

4.92

     

0.98

   

Class R5

   

1,000.00

     

1,000.00

     

988.30

     

1,020.54

     

4.30

     

4.37

     

0.87

   

Class Y

   

1,000.00

     

1,000.00

     

988.30

     

1,020.79

     

4.05

     

4.12

     

0.82

   

Class Z

   

1,000.00

     

1,000.00

     

987.90

     

1,020.29

     

4.55

     

4.62

     

0.92

   


21



UNDERSTANDING YOUR EXPENSES, continued

  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 Emerging Markets FundSM

 

Class A

   

1,000.00

     

1,000.00

     

1,011.70

     

1,015.76

     

9.15

     

9.17

     

1.83

   

Class C

   

1,000.00

     

1,000.00

     

1,007.80

     

1,011.93

     

12.98

     

13.01

     

2.60

   

Class I

   

1,000.00

     

1,000.00

     

1,014.60

     

1,017.70

     

7.21

     

7.22

     

1.44

   

Class R4

   

1,000.00

     

1,000.00

     

1,013.60

     

1,017.11

     

7.81

     

7.82

     

1.56

   

Class R5

   

1,000.00

     

1,000.00

     

1,013.60

     

1,017.60

     

7.31

     

7.32

     

1.46

   

Class Y

   

1,000.00

     

1,000.00

     

1,013.70

     

1,017.90

     

7.01

     

7.02

     

1.40

   

Class Z

   

1,000.00

     

1,000.00

     

1,012.70

     

1,017.01

     

7.91

     

7.92

     

1.58

   

Columbia Acorn European FundSM

 

Class A

   

1,000.00

     

1,000.00

     

961.60

     

1,016.16

     

8.54

     

8.77

     

1.75

   

Class C

   

1,000.00

     

1,000.00

     

958.60

     

1,012.43

     

12.17

     

12.51

     

2.50

   

Class I

   

1,000.00

     

1,000.00

     

963.00

     

1,017.85

     

6.88

     

7.07

     

1.41

   

Class R4

   

1,000.00

     

1,000.00

     

962.50

     

1,017.40

     

7.32

     

7.52

     

1.50

   

Class R5

   

1,000.00

     

1,000.00

     

962.70

     

1,017.60

     

7.12

     

7.32

     

1.46

   

Class Z

   

1,000.00

     

1,000.00

     

963.00

     

1,017.40

     

7.32

     

7.52

     

1.50

   

Fund of Funds—Columbia Thermostat Fund

January 1, 2016 – June 30, 2016

  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

 

Columbia Thermsotat FundSM

 

Class A

   

1,000.00

     

1,000.00

     

1,035.70

     

1,022.38

     

2.53

     

2.51

     

0.50

     

5.21

     

5.18

     

1.03

   

Class C

   

1,000.00

     

1,000.00

     

1,032.00

     

1,018.65

     

6.32

     

6.27

     

1.25

     

8.99

     

8.93

     

1.78

   

Class R4

   

1,000.00

     

1,000.00

     

1,036.70

     

1,023.62

     

1.27

     

1.26

     

0.25

     

3.95

     

3.92

     

0.78

   

Class R5

   

1,000.00

     

1,000.00

     

1,037.40

     

1,023.67

     

1.22

     

1.21

     

0.24

     

3.90

     

3.87