# EDGAR Filing Document

**Accession Number:** 0000887343
**File Stem:** 0000887343-26-000150
**Filing Date:** 2026-6
**Character Count:** 5343
**Document Hash:** 6cf928e573e3bce1228f8fa435771254
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000887343-26-000150.hdr.sgml**: 20260616

**ACCESSION NUMBER**: 0000887343-26-000150

**CONFORMED SUBMISSION TYPE**: 11-K/A

**PUBLIC DOCUMENT COUNT**: 13

**CONFORMED PERIOD OF REPORT**: 20251231

**FILED AS OF DATE**: 20260616

**DATE AS OF CHANGE**: 20260616

**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:** 11-K/A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-20288
- **FILM NUMBER:** 261095128

**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

?xml version='1.0' encoding='ASCII'? colb-20260616

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**Washington, D.C. 20549**

**___________________________________________________**

**FORM 11-K/A (Amendment No. 1)**

**___________________________________________________**

(Mark One)

⌧ **ANNUAL REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934**

**For the fiscal year ended DECEMBER 31, 2025** 

**OR**

[ ] **TRANSITION REPORT PURSUANT TO SECTION 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934**

**For the transition period from &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;to &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;.**

**Commission File Number.....000-20288**

**___________________________________________________**

A.&nbsp;&nbsp;&nbsp;&nbsp;Full title of the plan and the address of the plan, if different from that of the issuer named below:

**AMENDED AND RESTATED EMPLOYEE STOCK PURCHASE PLAN OF COLUMBIA BANKING SYSTEM, INC.** 

B.&nbsp;&nbsp;&nbsp;&nbsp;Name of issuer of the securities held pursuant to the plan and the address of its principal executive office:

**Columbia Banking System, Inc.** 

**1301 A Street**

**Tacoma, Washington 98402-4200** 

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**EXPLANATORY NOTE** 

This Amendment No. 1 to the Annual Report on Form 11-K of the Columbia Banking System, Inc. Employee Stock Purchase Plan (the "Plan") for the fiscal year ended December 31, 2025 is being filed solely to correct the auditor consent included as Exhibit 23.1 in the original filing.

The consent has been replaced with the consent of the appropriate independent registered public accounting firm.

No other changes have been made to the Form 11-K as originally filed with the U.S. Securities and Exchange Commission on March 31, 2026, and this Amendment does not modify or update any financial statements or other disclosures contained therein.

**PART II. OTHER INFORMATION** 

The only purpose of this Amendment No. 1 is to replace Exhibit 23.1 with the correct auditor consent. No other information contained in the original Form 11-K is amended hereby.

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**INDEX TO EXHIBITS**

**<u>Exhibit No.</u>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>Description</u>**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;23.1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<u>[Consent of Independent Registered Public Accounting Firm (Aprio, LLP)](colbesppex23111-kaconsent2.htm)</u>

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**SIGNATURES**

Pursuant to the requirements of the Securities and Exchange Act of 1934, the Plan Administrator has duly caused this annual report to be signed on its behalf by the undersigned hereunto duly authorized.

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| | |
|:---|:---|
| | **Amended and Restated Employee Stock Purchase Plan of Columbia Banking System, Inc.** |
| Date: June 16, 2026 | /s/ Brock Lakely |
| | Brock Lakely |
| | Executive Vice President, Chief Accounting Officer and Principal Accounting Officer |

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## Exhibit 23.1

Exhibit 23.1

**CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM**

We consent to the incorporation by reference in Registration Statement Nos. 333-273424, 333-270191, 333-160371, 333-225955, 333-279235, 333-279237, 333-279238 and 333-289981 on Form S-8 and Registration Statement No. 333-283985 on Form S-3 of Columbia Banking System, Inc. of our report dated March 31, 2026, relating to the financial statements of the Amended and Restated Employee Stock Purchase Plan of Columbia Banking System, Inc. appearing in this Annual Report on Form 11-K for the year ended December 31, 2025.

/s/ Aprio, LLP

Lake Oswego, Oregon

March 31, 2026

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