# EDGAR Filing Document

**Accession Number:** 0000002110
**File Stem:** 0001193125-23-070874
**Filing Date:** 2023-3
**Character Count:** 5251
**Document Hash:** 5b2f276edbd871904e73405d7a167f01
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-23-070874.hdr.sgml**: 20230315

**ACCESSION NUMBER**: 0001193125-23-070874

**CONFORMED SUBMISSION TYPE**: 497

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20230315

**DATE AS OF CHANGE**: 20230315

**EFFECTIVENESS DATE**: 20230315

**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:** 23733822

**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 March 15, 2023
to the Statement of Additional Information (SAI) of the following Fund:

---

| | |
|:---|:---|
| &nbsp;&nbsp;**Fund** | &nbsp;&nbsp;**SAI Dated** |
| &nbsp;&nbsp;Columbia Acorn Trust | |
| &nbsp;&nbsp; Columbia Thermostat Fund | &nbsp;&nbsp;May 1, 2022 |

---

*Effective immediately, all references to Anwiti Bahuguna in the SAI are hereby removed. Additionally, the information in the "Investment Advisory and Other Services — The Investment Manager and Investment Advisory Services" section of the SAI is hereby revised as described below.*

1. The information under the caption "Portfolio Managers of the Investment Manager" is hereby revised to add the following:

---

| | |
|:---|:---|
| **Portfolio Manager** | &nbsp;&nbsp;**Fund** |
| Corey Lorenzen, CFA | &nbsp;&nbsp;Columbia Thermostat Fund |

---

2. The information under the caption "Performance Benchmarks" is hereby revised to add the following:

---

| |
|:---|
| **Portfolio Manager** |
| Corey Lorenzen (Columbia Thermostat Fund) &nbsp;&nbsp;S&P 500<sup>®</sup> Index (primary equity benchmark), Bloomberg U.S. Aggregate Bond Index (primary debt benchmark) and the Blended Benchmark (an equally weighted custom composite of the Fund's primary equity and debt benchmarks, established by the Investment Manager) |

---

3. The information under the caption "Other Accounts Managed by the Portfolio Managers as of December 31, 2021" is hereby revised to add the following:

---

| | | | |
|:---|:---|:---|:---|
| **Fund** | **Portfolio Manager** | &nbsp;&nbsp;**Number and Type of<br> Account\*** | &nbsp;&nbsp;**Approximate Total<br> Net Assets** |
| Columbia Thermostat Fund | Corey Lorenzen\*\*\* | &nbsp;&nbsp;1 RIC<br> 6 Other Accounts | &nbsp;&nbsp;$37.29 million<br> $0.92 million |

---

\*\*\* The portfolio manager began managing the Fund after its last fiscal year end; reporting information is provided as of February 28, 2023.

4. The information under the caption "Portfolio Manager Ownership as of December 31, 2021" is hereby revised to add the following:

---

| | | |
|:---|:---|:---|
| **Portfolio Manager** | &nbsp;&nbsp;&nbsp;&nbsp;**Fund** | &nbsp;&nbsp;&nbsp;&nbsp;**Dollar Range of Equity Securities<br> in the Fund Beneficially Owned** |
| Corey Lorenzen | &nbsp;&nbsp;&nbsp;&nbsp;Columbia Thermostat Fund | &nbsp;&nbsp;&nbsp;&nbsp;—\*\* |

---

\*\* The portfolio manager began managing the Fund after its last fiscal year end; reporting information is provided as of February 28, 2023.

*The rest of the section remains the same.*

*Shareholders should retain this Supplement for future reference.*

SUP900_00_020_(03/23)