# EDGAR Filing Document

**Accession Number:** 0000887343
**File Stem:** 0000887343-25-000277
**Filing Date:** 2025-12
**Character Count:** 5494
**Document Hash:** 469ad853990b5a332febf232da031aca
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000887343-25-000277.hdr.sgml**: 20251201

**ACCESSION NUMBER**: 0000887343-25-000277

**CONFORMED SUBMISSION TYPE**: 3

**PUBLIC DOCUMENT COUNT**: 3

**CONFORMED PERIOD OF REPORT**: 20251120

**FILED AS OF DATE**: 20251201

**DATE AS OF CHANGE**: 20251201

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Lakely Brock
- **CENTRAL INDEX KEY:** 0001740374

**ORGANIZATION NAME:**

**FILING VALUES:**
- **FORM TYPE:** 3
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-20288
- **FILM NUMBER:** 251541305

**MAIL ADDRESS:**
- **STREET 1:** C/O COLUMBIA BANKING SYSTEM, INC.
- **STREET 2:** 1301 A STREET
- **CITY:** TACOMA
- **STATE:** WA
- **ZIP:** 98402
**ISSUER**: 

**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

**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

## Ex-24

![](a2025-11x20powerofattorn001.jpg)

------

### UNITED STATES SECURITIES AND EXCHANGE COMMISSION
**Washington, D.C. 20549**

## FORM 3

### INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

[ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Lakely Brock<br><sub>(Last) (First) (Middle)</sub><br>C/O COLUMBIA BANKING SYSTEM, INC.<br>1301 A STREET<br><sub>(Street)</sub><br>TACOMA, WA 98402<br><sub>(City) (State) (Zip)</sub> | **3. Issuer Name and Ticker or Trading Symbol**<br>COLUMBIA BANKING SYSTEM, INC. [ COLB ] | **5. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  |
| **2. Date of Event Requiring Statement (Month/Day/Year)**<br>2025-11-20 | **4. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[ ] Director   [ ] 10% Owner<br>[X] Officer (give title below)   [ ] Other (specify below)<br>_EVP, Chief Accounting Officer_ | **6. Individual or Joint/Group Filing (Check Applicable Line)**<br>[X] Form filed by One Reporting Person<br>[ ] Form filed by More than One Reporting Person |

---

## Table I - Non-Derivative Securities Beneficially Owned

---

|  |  |  |  |
| --- | --- | --- | --- |
| 1. Title of Security | 2. Amount of Securities Beneficially Owned | 3. Ownership Form | 4. Nature of Indirect Beneficial Ownership |
| Common Stock | 10860 | D |  |

---

## Table II - Derivative Securities Beneficially Owned

---

|  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 2. Date Exercisable and Expiration Date (Month/Day/Year) | 3. Title and Amount of Underlying Securities | 3. Title and Amount of Underlying Securities | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 4. Conversion or Exercise Price | 5. Ownership Form | 6. Nature of Indirect Beneficial Ownership |
| Restricted Stock Unit | <sup>(1)(2)</sup> | <sup>(1)(2)</sup> | Common Stock | 5055 | <sup>(1)(2)</sup> | D |  |
| Performance Restricted Stock Unit | <sup>(3)(4)</sup> | <sup>(3)(4)</sup> | Common Stock | 6312 | <sup>(3)(4)</sup> | D |  |

---

### Footnotes:

(1) 2,537 restricted stock units granted 02/25/2025. The grant will vest 33.33% per year over three years.

(2) 2,518 restricted stock units granted 03/01/2024. The grant will vest 33.33% per year over two years.

(3) 2,536 performance-based restricted stock units granted 02/25/2025. The grant will vest approximately three years following the grant date based on the issuer's relative total shareholder return and return on tangible common equity for fiscal years 2025-2027 compared to a group of peer companies approved by the issuer's compensation committee.

(4) 3,776 performance-based restricted stock units granted 03/01/2024. The grant will vest approximately three years following the grant date based on the issuer's relative total shareholder return performance and return on tangible common equity for fiscal years 2024-2026 compared to a group of peer companies approved by the issuer's compensation committee.

**Signature:** /s/ Andrea M. Newburn, Attorney-in-fact  
**Date:** 2025-12-01

### Remarks:

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.

**Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.**