# EDGAR Filing Document

**Accession Number:** 0000887343
**File Stem:** 0000887343-26-000127
**Filing Date:** 2026-3
**Character Count:** 2611
**Document Hash:** a7c1a2e5920c168bc3399be19dde3ae0
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000887343-26-000127.hdr.sgml**: 20260331

**ACCESSION NUMBER**: 0000887343-26-000127

**CONFORMED SUBMISSION TYPE**: DEFA14A

**PUBLIC DOCUMENT COUNT**: 4

**FILED AS OF DATE**: 20260331

**DATE AS OF CHANGE**: 20260331

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** COLUMBIA BANKING SYSTEM, INC.
- **CENTRAL INDEX KEY:** 0000887343
- **STANDARD INDUSTRIAL CLASSIFICATION:** STATE COMMERCIAL BANKS [6022]
- **ORGANIZATION NAME:** 02 Finance
- **EIN:** 911422237
- **STATE OF INCORPORATION:** WA
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-20288
- **FILM NUMBER:** 26823559

**BUSINESS ADDRESS:**
- **STREET 1:** 1301 A STREET
- **CITY:** TACOMA
- **STATE:** WA
- **ZIP:** 98402
- **BUSINESS PHONE:** 2533051900

**MAIL ADDRESS:**
- **STREET 1:** 1301 A STREET
- **CITY:** TACOMA
- **STATE:** WA
- **ZIP:** 98402

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** COLUMBIA BANKING SYSTEM INC
- **DATE OF NAME CHANGE:** 19930328

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, DC 20549**

![image_2.jpg](image_2.jpg)

**SCHEDULE 14A**

**SCHEDULE 14A INFORMATION**

**Proxy Statement Pursuant to Section 14(a)**

**of the Securities Exchange Act of 1934 (Amendment No.)**

<br> ![image_2.jpg](image_2.jpg)<br>

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| | |
|:---|:---|
| Filed by the Registrant ☒ | Filed by the Registrant ☒ |
| Filed by a Party other than the Registrant ☐ | Filed by a Party other than the Registrant ☐ |
| Check the appropriate box: | Check the appropriate box: |
| ☐ | Preliminary Proxy Statement |
| ☐ | **Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))** |
| ☐ | Definitive Proxy Statement |
| ☒ | Definitive Additional Materials |
| ☐ | Soliciting Material under §240.14a-12 |

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| |
|:---|
| **Columbia Banking System, Inc.** |
| **(Name of Registrant as Specified In Its Charter)** |
| **(Name of Person(s) Filing Proxy Statement, if other than the Registrant)** |

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| | |
|:---|:---|
| Payment of Filing Fee (Check the appropriate box): | Payment of Filing Fee (Check the appropriate box): |
| Check the appropriate box: | Check the appropriate box: |
| ☒ | No fee required. |
| ☐ | Fee paid previously with preliminary materials. |
| ☐ | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and 0-11. |

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![columbiabankingsysteminc_v.jpg](columbiabankingsysteminc_v.jpg)

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![columbiabankingsysteminc_va.jpg](columbiabankingsysteminc_va.jpg)

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