# EDGAR Filing Document

**Accession Number:** 0001550429
**File Stem:** 0000887343-23-000095
**Filing Date:** 2023-3
**Character Count:** 9893
**Document Hash:** ad3380bcf20f9f39e70d980edaf302a4
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0000887343-23-000095.hdr.sgml**: 20230302

**ACCESSION NUMBER**: 0000887343-23-000095

**CONFORMED SUBMISSION TYPE**: 4

**PUBLIC DOCUMENT COUNT**: 2

**CONFORMED PERIOD OF REPORT**: 20230228

**FILED AS OF DATE**: 20230302

**DATE AS OF CHANGE**: 20230302

**REPORTING-OWNER**: 

**OWNER DATA:**
- **COMPANY CONFORMED NAME:** Stein Clint
- **CENTRAL INDEX KEY:** 0001550429

**FILING VALUES:**
- **FORM TYPE:** 4
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 000-20288
- **FILM NUMBER:** 23700756

**MAIL ADDRESS:**
- **STREET 1:** 1301 A STREET, SUITE 800
- **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]
- **IRS NUMBER:** 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

```
<pre>
Power of Attorney

The undersigned hereby constitutes and appoints Kumi Yamamoto Baruffi, Ronald L. Farnsworth, Neal T. McLaughlin, Andrea M. Newburn and Lisa White as the undersigned's attorneys-in-fact to (1) execute and file for and on behalf of the undersigned, all reports of, and changes in, beneficial ownership by the undersigned of securities of Columbia Banking System, Inc. (the "Company") as may be required by Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder, and any other forms or reports the undersigned may be required to file in connection with the undersigned's ownership, acquisition, or disposition of securities of the Company, including forms required to generate codes for the Securities and Exchange Commission's electronic filing system; (2) do and perform any and all acts for and on behalf of the undersigned which may be necessary or desirable to complete and execute and file any such reports with the United States Securities and Exchange Commission and any stock exchange or similar authority; and (3) take any other action of any nature whatsoever in connection with the foregoing that, in the opinion of such attorneys-in-fact, may be of benefit to, and in the best interest of, or legally required of, the undersigned.

The undersigned hereby grants to said attorneys-in-fact, each acting alone, full power and authority to do and perform any and every act and thing whatsoever requisite, necessary, or proper to be done in the exercise of any of the rights and powers herein granted, as fully to all intents and purposes as the undersigned might or could do if personally present, with full power of substitution or revocation, hereby ratifying and confirming all that such attorneys-in-fact, or such attorneys-in-facts substitute or substitutes, shall lawfully do or cause to be done by the virtue of this Power of Attorney and the rights and powers herein granted. The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, are not assuming, nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of 1934.

This Power of Attorney shall remain in full force and effect until the undersigned is no longer required to file reports pursuant to Section 16(a) of the Securities Exchange Act of 1934 and the rules thereunder with respect to the undersigned's holdings of and transactions in securities issued by the Company, unless earlier revoked by the undersigned in a signed writing delivered to the attorneys-in-fact. The undersigned acknowledges that none of the Company, Kumi Yamamoto Baruffi, Ronald L. Farnsworth, Neal T. McLaughlin, Andrea M. Newburn and Lisa White are assuming any of the undersigned's responsibilities to comply with Section 16 of the Securities and Exchange Act of 1934.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of February 28, 2023.

Signature: /s/ Clint Stein
Name: Clint Stein

Notarization/Certification
State of Washington County of Pierce

Signed or attested before me on 02/28/2023 by Clint Stein.

/s/ Karina Busch
Notary/Agent/Subagent signature

Karina Busch
Notary printed or stamped name

07/01/2024
Notary expiration date
</pre>
```

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

## FORM 4

### STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

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

[ ] Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

---

| | | |
|:---|:---|:---|
| **1. Name and Address of Reporting Person**<sup>*</sup><br>Stein Clint<br><sub>(Last) (First) (Middle)</sub><br>C/O COLUMBIA BANKING SYSTEM, INC.<br>PO BOX 2156, MS 3100<br><sub>(Street)</sub><br>TACOMA, WA 98401-2156<br><sub>(City) (State) (Zip)</sub> | **3. Date of Earliest Transaction (Month/Day/Year)**<br>2023-02-28 | **5. Relationship of Reporting Person(s) to Issuer**<br>(Check all applicable)<br>[X] Director [ ] 10% Owner<br>[X] Officer (give title below) [ ] Other (specify below)<br>_President, CEO_ |
| **2. Issuer Name and Ticker or Trading Symbol**<br>COLUMBIA BANKING SYSTEM, INC. [ COLB ] | **4. If Amendment, Date of Original Filed (Month/Day/Year)**<br>  | **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

---

|  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | 3. Transaction Code (V) | 3. Transaction Code (V) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 4. Securities Acquired (A) or Disposed of (D) | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| 1. Title of Security | 2. Transaction Date | 2A. Deemed Execution Date | Code | V | Amount | (A) or (D) | Price | 5. Amount of Securities Beneficially Owned | 6. Ownership Form | 7. Nature of Indirect Beneficial Ownership |
| Common Stock | 2023-02-28 |  | A |  | 7860<sup>(1)</sup> | A | $0 | 108108 | D |  |
| Common Stock | 2023-02-28 |  | A |  | 7860<sup>(1)</sup> | A | $0 | 115968 | D |  |
| Common Stock | 2023-02-28 |  | A |  | 16173<sup>(1)</sup> | A | $0 | 132141 | D |  |
| Common Stock | 2023-02-28 |  | A |  | 14440<sup>(1)</sup> | A | $0 | 146581 | D |  |

---

## Table II - Derivative Securities

---

|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | 4. Transaction Code (V) | 4. Transaction Code (V) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 5. Number of Derivative Securities Acquired (A) or Disposed of (D) | 6. Date Exercisable and Expiration Date | 6. Date Exercisable and Expiration Date | 7. Title and Amount of Underlying Securities | 7. Title and Amount of Underlying Securities | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
| 1. Title of Derivative Security | 2. Conversion or Exercise Price | 3. Transaction Date | 3A. Deemed Execution Date | Code | V | (A) | (D) | Date Exercisable | Expiration Date | Title | Amount or Number of Shares | 8. Price of Derivative Security | 9. Number of Derivative Securities Beneficially Owned | 10. Ownership Form | 11. Nature of Indirect Beneficial Ownership |
|  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

---

### Footnotes:

(1) At the effective time of the merger (the "Effective Time") of Cascade Merger Sub, Inc. ("Merger Sub"), a direct, wholly-owned subsidiary of the Issuer, with and into Umpqua Holdings Corporation ("Umpqua"), pursuant to that certain Agreement and Plan of Merger, dated as of October 11, 2021 (the "Merger Agreement"), by and among the Issuer, Umpqua and Merger Sub, each outstanding performance stock unit award of the Issuer granted under the Issuer's equity compensation plans was converted into a restricted stock unit award of the Issuer based on a level of performance determined in accordance with the Merger Agreement, with such awards continuing to vest after the Effective Time solely based on continued service.

**Signature:** /s/ Andrea M. Newburn, Attorney-in-fact  
**Date:** 2023-03-02

### 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.**