# EDGAR Filing Document

**Accession Number:** 0000002110
**File Stem:** 0001193125-23-052642
**Filing Date:** 2023-2
**Character Count:** 6007
**Document Hash:** 5075f0f17bbb4b5038a06c6c3f4d2584
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-23-052642.hdr.sgml**: 20230228

**ACCESSION NUMBER**: 0001193125-23-052642

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20230228

**DATE AS OF CHANGE**: 20230228

**EFFECTIVENESS DATE**: 20230228

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COLUMBIA ACORN TRUST
- **CENTRAL INDEX KEY:** 0000002110
- **IRS NUMBER:** 362692100
- **STATE OF INCORPORATION:** MA
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 497
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 002-34223
- **FILM NUMBER:** 23678909

**BUSINESS ADDRESS:**
- **STREET 1:** 71 S. WACKER DRIVE, SUITE 2500
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606
- **BUSINESS PHONE:** 3126349200

**MAIL ADDRESS:**
- **STREET 1:** 71 S. WACKER DRIVE, SUITE 2500
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** LIBERTY ACORN TRUST
- **DATE OF NAME CHANGE:** 20010424

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ACORN INVESTMENT TRUST
- **DATE OF NAME CHANGE:** 19940204

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** ACORN FUND INC
- **DATE OF NAME CHANGE:** 19920703

## Series and Classes Contracts Data

### Columbia Thermostat Fund (Series ID: S000009189)

---

|  |  |  |
|:---|:---|:---|
| Class Name                                     | Ticker Symbol | Class ID   |
| Columbia Thermostat Fund Class A               | CTFAX         | C000024974 |
| Columbia Thermostat Fund Class C               | CTFDX         | C000024976 |
| Columbia Thermostat Fund Institutional Class   | COTZX         | C000024977 |
| Columbia Thermostat Fund Advisor Class         | CTORX         | C000122749 |
| Columbia Thermostat Fund Institutional 2 Class | CQTRX         | C000122750 |
| Columbia Thermostat Fund Institutional 3 Class | CYYYX         | C000122751 |

---

## Series and Classes Contracts Data

### Columbia Thermostat Fund (Series ID: S000009189)

| Class ID   | Class Name                                     | Ticker Symbol   |
|:---|:---|:---|
| C000024974 | Columbia Thermostat Fund Class A               | CTFAX           |
| C000024976 | Columbia Thermostat Fund Class C               | CTFDX           |
| C000024977 | Columbia Thermostat Fund Institutional Class   | COTZX           |
| C000122749 | Columbia Thermostat Fund Advisor Class         | CTORX           |
| C000122750 | Columbia Thermostat Fund Institutional 2 Class | CQTRX           |
| C000122751 | Columbia Thermostat Fund Institutional 3 Class | CYYYX           |

#### Supplement dated February 28, 2023
to the Prospectus and Summary Prospectus of the following Fund:

---

| | |
|:---|:---|
| &nbsp;&nbsp;**Fund** | &nbsp;&nbsp;**Prospectus and Summary Prospectus Dated** |
| &nbsp;&nbsp;Columbia Acorn Trust | |
| &nbsp;&nbsp; Columbia Thermostat Fund | &nbsp;&nbsp;5/1/2022 |

---

*Effective immediately, the portfolio manager information under the heading "Fund Management" in the Summary Prospectus and the "Summary of the Fund" section of the Prospectus, is hereby superseded and replaced with the following:*

*&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;*

<br> ---

| | | | |
|:---|:---|:---|:---|
| **Portfolio Management** | &nbsp;&nbsp;&nbsp;&nbsp;**Title** | &nbsp;&nbsp;&nbsp;&nbsp;**Role with Fund** | &nbsp;&nbsp;&nbsp;&nbsp;**Service with the Fund Since** |
| Alex M. Rivas | &nbsp;&nbsp;&nbsp;&nbsp;Portfolio Manager and Assistant Vice President of the Investment Manager | &nbsp;&nbsp;&nbsp;&nbsp;Portfolio Manager<br> since May 2022 | &nbsp;&nbsp;&nbsp;&nbsp;2018 |
| Corey Lorenzen, CFA | &nbsp;&nbsp;&nbsp;&nbsp;Associate Portfolio Manager of Columbia Management and Vice President of the Investment Manager | &nbsp;&nbsp;&nbsp;&nbsp;Portfolio Manager<br> since February 2023 | &nbsp;&nbsp;&nbsp;&nbsp;February 2023 |

---

*The portfolio manager information under the heading "Primary Service Provider Contracts — Portfolio Managers" in the "More Information About the Fund" section of the Prospectus is hereby superseded and replaced with the following:*

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

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<br>

---

| | | | |
|:---|:---|:---|:---|
| **Portfolio Management** | &nbsp;&nbsp;&nbsp;&nbsp;**Title** | &nbsp;&nbsp;&nbsp;&nbsp;**Role with Fund** | &nbsp;&nbsp;&nbsp;&nbsp;**Service with the Fund Since** |
| Alex M. Rivas | &nbsp;&nbsp;&nbsp;&nbsp;Portfolio Manager and Assistant Vice President of the Investment Manager | &nbsp;&nbsp;&nbsp;&nbsp;Portfolio Manager<br> since May 2022 | &nbsp;&nbsp;&nbsp;&nbsp;2018 |
| Corey Lorenzen, CFA | &nbsp;&nbsp;&nbsp;&nbsp;Associate Portfolio Manager of Columbia Management and Vice President of the Investment Manager | &nbsp;&nbsp;&nbsp;&nbsp;Portfolio Manager<br> since February 2023 | &nbsp;&nbsp;&nbsp;&nbsp;February 2023 |

---

**Mr. Rivas joined Columbia Management, an affiliate of the Investment Manager in 2017. Mr. Rivas has served as Assistant Vice President of the Investment Manager since February 2018. Prior to joining Columbia Management, Mr. Rivas was a trading specialist with Blackrock Advisors, LLC. Mr. Rivas began his investment career in 2009 and earned a B.S. from Georgia Institute of Technology and a Master's degree in Finance from Princeton University.**

**Mr. Lorenzen joined Columbia Management, an affiliate of the Investment Manager in 2012. Mr. Lorenzen began his investment career in 2012 and earned a B.S. from the University of Wisconsin - Madison and an M.S. from the University of Wisconsin - Milwaukee.**

*Shareholders should retain this Supplement for future reference.*

SUP235_12_009_(02/23)