# EDGAR Filing Document

**Accession Number:** 0000002110
**File Stem:** 0001193125-25-195569
**Filing Date:** 2025-9
**Character Count:** 5177
**Document Hash:** 6f74322cf0566e21e60b44d13bee628f
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-195569.hdr.sgml**: 20250904

**ACCESSION NUMBER**: 0001193125-25-195569

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250904

**DATE AS OF CHANGE**: 20250904

**EFFECTIVENESS DATE**: 20250904

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COLUMBIA ACORN TRUST
- **CENTRAL INDEX KEY:** 0000002110

**ORGANIZATION NAME:**
- **EIN:** 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:** 251292115

**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 Acorn Fund (Series ID: S000009184)

---

|  |  |  |
|:---|:---|:---|
| Class Name                                | Ticker Symbol | Class ID   |
| Columbia Acorn Fund Class A               | LACAX         | C000024954 |
| Columbia Acorn Fund Class C               | LIACX         | C000024956 |
| Columbia Acorn Fund Institutional Class   | ACRNX         | C000024957 |
| Columbia Acorn Fund Institutional 2 Class | CRBRX         | C000122736 |
| Columbia Acorn Fund Institutional 3 Class | CRBYX         | C000122737 |
| Columbia Acorn Fund Class S               | ACRSX         | C000251059 |

---

## Series and Classes Contracts Data

### Columbia Acorn Fund (Series ID: S000009184)

| Class ID   | Class Name                                | Ticker Symbol   |
|:---|:---|:---|
| C000024954 | Columbia Acorn Fund Class A               | LACAX           |
| C000024956 | Columbia Acorn Fund Class C               | LIACX           |
| C000024957 | Columbia Acorn Fund Institutional Class   | ACRNX           |
| C000122736 | Columbia Acorn Fund Institutional 2 Class | CRBRX           |
| C000122737 | Columbia Acorn Fund Institutional 3 Class | CRBYX           |
| C000251059 | Columbia Acorn Fund Class S               | ACRSX           |

**Supplement dated September 4, 2025**

to the Prospectus and Summary Prospectus of the following fund (the Fund):

---

| | |
|:---|:---|
| **Fund** | **Prospectus and Summary Prospectus Dated** |
| Columbia Acorn Trust |  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Columbia Acorn<sup>®</sup> Fund | May 1, 2025 |

---

*Effective immediately, the following changes are hereby made to the Fund's Prospectus and Summary Prospectus.*

*The portfolio manager information under the caption "Fund Management" in the Summary Prospectus and in the "Summary of the Fund" section of the Prospectus is hereby superseded and replaced with the following:* 

---

| | | | |
|:---|:---|:---|:---|
| **Portfolio Management** | **Title** | **Role with Fund** | **Managed Fund Since** |
| Erika Maschmeyer, CFA | Senior Portfolio Manager | Lead Portfolio Manager | &nbsp;&nbsp;&nbsp;&nbsp; Portfolio Manager since 2019;<br> Service with the Fund since 2016<br>|
| Pratyasha Rath | Portfolio Manager  | Portfolio Manager | September 2025 |

---

*The portfolio manager information under the "Primary Service Provider Contracts" caption in the "More Information About the Fund" section of the Prospectus is hereby revised 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.

---

| | | | |
|:---|:---|:---|:---|
| **Portfolio Management** | **Title** | **Role with Fund** | **Managed Fund Since** |
| Erika Maschmeyer, CFA | Senior Portfolio Manager | Lead Portfolio Manager | &nbsp;&nbsp;&nbsp;&nbsp; Portfolio Manager since 2019;<br> Service with the Fund since 2016<br>|
| Pratyasha Rath | Portfolio Manager  | Portfolio Manager | September 2025 |

---

**Ms. Maschmeyer** has been associated with the Investment Manager or one of its affiliates since 2016. Ms. Maschmeyer began her investment career in 2001 and earned a B.A. from Denison University and an M.B.A from the University of Chicago.

**Ms. Rath** has been associated with the Investment Manager or one of its affiliates since 2017. Ms. Rath began her investment career in 2007 and earned a B.A. from Delhi University, India and an M.S. from the Illinois Institute of Technology, Chicago.

*The rest of the Prospectus and Summary Prospectus remain unchanged.*

*Shareholders should retain this Supplement for future reference.*

SUP110_12_013_(09/25)

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