# EDGAR Filing Document

**Accession Number:** 0001097519
**File Stem:** 0001193125-25-195580
**Filing Date:** 2025-9
**Character Count:** 4455
**Document Hash:** aa5362ec0488949cd7cf4994d19d9ed9
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-25-195580.hdr.sgml**: 20250904

**ACCESSION NUMBER**: 0001193125-25-195580

**CONFORMED SUBMISSION TYPE**: 497K

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20250904

**DATE AS OF CHANGE**: 20250904

**EFFECTIVENESS DATE**: 20250904

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COLUMBIA FUNDS SERIES TRUST
- **CENTRAL INDEX KEY:** 0001097519

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 0331

**FILING VALUES:**
- **FORM TYPE:** 497K
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-89661
- **FILM NUMBER:** 251292124

**BUSINESS ADDRESS:**
- **STREET 1:** 290 CONGRESS STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210
- **BUSINESS PHONE:** 800-345-6611

**MAIL ADDRESS:**
- **STREET 1:** 290 CONGRESS STREET
- **CITY:** BOSTON
- **STATE:** MA
- **ZIP:** 02210

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** NATIONS FUNDS TRUST
- **DATE OF NAME CHANGE:** 19991022

## Series and Classes Contracts Data

### Columbia Mid Cap Index Fund (Series ID: S000010826)

| Class ID   | Class Name                                        | Ticker Symbol   |
|:---|:---|:---|
| C000030054 | Columbia Mid Cap Index Fund Class A               | NTIAX           |
| C000030055 | Columbia Mid Cap Index Fund Institutional Class   | NMPAX           |
| C000122594 | Columbia Mid Cap Index Fund Institutional 2 Class | CPXRX           |
| C000173200 | Columbia Mid Cap Index Fund Institutional 3 Class | CMDYX           |

**Supplement dated September 4, 2025**

to the Prospectus and Summary Prospectus of each of the following funds

(each, a Fund, and collectively, the Funds):

---

| | |
|:---|:---|
| **Fund** | **Prospectus and Summary Prospectus Dated** |
| Columbia Funds Series Trust |  |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Columbia Large Cap Index Fund | 7/1/2025 |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Columbia Mid Cap Index Fund | 7/1/2025 |
| &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Columbia Small Cap Index Fund | 7/1/2025 |

---

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

*The portfolio manager information under the heading "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** |
| Christopher Lo, CFA | Senior Portfolio Manager | Lead Portfolio Manager | 2014 |
| Shirley Wang, CFA, CPA | Associate Portfolio Manager | Portfolio Manager | September 2025 |

---

*The rest of the section remains the same.*

*The portfolio manager information under the heading "Primary Service Provider Contracts – Portfolio Manager" 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.

---

| | | | |
|:---|:---|:---|:---|
| **Portfolio Management** | **Title** | **Role with Fund** | **Managed Fund Since** |
| Christopher Lo, CFA | Senior Portfolio Manager | Lead Portfolio Manager | 2014 |
| Shirley Wang, CFA, CPA | Associate Portfolio Manager | Portfolio Manager | September 2025 |

---

**Dr. Lo** joined one of the Columbia Management legacy firms or acquired business lines in 1998. Dr. Lo began his investment career in 1998 and earned a B.S. and M.E. from Rensselaer Polytechnic Institute, an M.B.A. from the Stern School of Business at New York University and a doctoral degree in professional studies (DPS) from Pace University, with a concentration in finance and international economics.

**Ms. Wang** joined one of the Columbia Management legacy firms or acquired business lines in 2002. Ms. Wang began her investment career in 1998 and earned a B.S. in Business Administration from Boston University.

*The rest of the section remains the same.*

*Shareholders should retain this Supplement for future reference.*

SUP000_00_177_(09/25)

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