# EDGAR Filing Document

**Accession Number:** 0000002110
**File Stem:** 0001193125-25-198390
**Filing Date:** 2025-9
**Character Count:** 5471
**Document Hash:** 4523f58827ac62a35f5b08aea7ba24c3
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-198390.hdr.sgml**: 20250908

**ACCESSION NUMBER**: 0001193125-25-198390

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250908

**DATE AS OF CHANGE**: 20250908

**EFFECTIVENESS DATE**: 20250908

**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:** 251300325

**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 8, 2025***

to the Statement of Additional Information (SAI), as supplemented, of the following fund:

---

| | |
|:---|:---|
| **Fund** | **SAI Dated** |
| **Columbia Acorn Trust** |  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Columbia Acorn Fund | &nbsp;&nbsp; 5/1/2025 |

---

*Effective immediately, the information under the subsection "The Investment Manager and Subadvisers – Portfolio Managers" in the "Investment Management and Other Services" section of the SAI with respect to the Fund is hereby superseded and replaced with the following:* 

---

| | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|
|  |  | **Other Accounts Managed (excluding the Fund)** | **Other Accounts Managed (excluding the Fund)** | **Other Accounts Managed (excluding the Fund)** | **Ownership**<br> **of Fund**<br> **Shares** | **Potential**<br> **Conflicts**<br> **of Interest** | **Structure**<br> **of**<br> **Compensation** |
| **Fund** | **Portfolio**<br> **Manager**<br>| **Number**<br> **and Type**<br> **of Account**<sup>(1)</sup> <br>| **Approximate**<br> **Total Net**<br> **Assets**<br>| **Performance-**<br> **Based**<br> **Accounts**<sup>(2)</sup> <br>| **Ownership**<br> **of Fund**<br> **Shares** | **Potential**<br> **Conflicts**<br> **of Interest** | **Structure**<br> **of**<br> **Compensation** |
| ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** | ***Information About the Portfolio Managers as of December 31, 2024*** |
| Columbia Acorn Fund | Erika Maschmeyer | 1 RIC<br> 1 PIV<br> 7 other<br> accounts<br>| $516.71 million<br> $4.31 million<br> $2.37 million<br>|  | $100,001 –<br> $500,000<br> (Vested)<br> $100,001 –<br> $500,000<br> (Notional)<br>| Columbia <br> Management | Columbia <br> Management |
| Columbia Acorn Fund | Pratyasha Rath<sup>(3)</sup> <br>| 5 other<br> accounts<br>| $1.08 million |  |  | Columbia <br> Management | Columbia <br> Management |

---

(1) "RIC" in this context refers to an SEC-registered investment company; "PIV" refers to a pooled investment vehicle.

(2) Number and type of accounts for which the advisory fee paid is based in part or wholly on performance and the aggregate net assets in those accounts.

(3) The portfolio manager began managing the Fund after its last fiscal year end; reporting information is provided as of July 31, 2025.

*The rest of the section remains the same.*

*Shareholders should retain this Supplement for future reference.*

SUP900_00_026_(09/25)

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