Columbia Banking (COLB) EVP vests 940 RSUs with 376 shares for taxes

Rhea-AI Filing Summary

COLUMBIA BANKING SYSTEM, INC. executive David Devine Moore, EVP Chief Marketing Officer, exercised Restricted Stock Units that converted into 940 shares of common stock on March 13, 2026. These RSUs were part of a 2,819-unit grant made on February 25, 2025 that vests in three annual installments beginning March 13, 2026.

Of the 940 common shares received, 376 shares were disposed of to cover tax liabilities through share withholding at a reference price of $26.23 per share. After these transactions, Moore directly holds 22,508 shares of common stock and 4,679 Restricted Stock Units.

SEC Form 4

FORM 4

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

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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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^*

Moore Devine David

(Last) (First) (Middle)

C/O COLUMBIA BANKING SYSTEM, INC.

1301 A STREET

(Street)

TACOMA WA 98402

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
COLUMBIA BANKING SYSTEM, INC. [ COLB ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP Chief Marketing Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/13/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/13/2026		M		940	A	$26.23	22,884	D
Common Stock	03/13/2026		F		376	D	$26.23	22,508	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Restricted Stock Unit	(1)	03/13/2026		M			940	(1)	(1)	Common Stock	940	$0	4,679	D

Explanation of Responses:

1. Restricted Stock Units convert into common stock on a one-for-one basis. On February 25, 2025, the reporting person was granted 2,819 Restricted Stock Units, which vest in three annual installments beginning on March 13, 2026.

Remarks:

	/s/ Andrea M. Newburn, Attorney-in-fact	03/17/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transaction did COLB executive David Devine Moore report?

David Devine Moore reported exercising Restricted Stock Units that converted into 940 common shares. These units were part of a prior equity grant and represent a scheduled vesting event rather than an open-market purchase, reflecting routine equity compensation for a senior executive.

How many Columbia Banking (COLB) shares did the EVP receive and retain?

Moore received 940 common shares upon RSU conversion. Of these, 376 shares were withheld to satisfy tax obligations at $26.23 per share, leaving 564 net new shares. Following the transactions, his direct common stock holdings total 22,508 shares.

What was the origin of the Restricted Stock Units in this COLB Form 4?

The Restricted Stock Units came from a grant of 2,819 units awarded on February 25, 2025. According to the footnote, this grant vests in three equal annual installments beginning March 13, 2026, making the reported 940-unit conversion the first scheduled vesting tranche.

How were taxes handled on David Devine Moore’s COLB stock award?

Taxes were satisfied through a share withholding mechanism. Out of the 940 common shares issued on RSU vesting, 376 shares were disposed of at a reference price of $26.23 per share specifically to pay exercise price or tax liabilities, rather than being sold on the open market.

How many Columbia Banking (COLB) shares does the EVP hold after this filing?

After the reported transactions, Moore directly owns 22,508 shares of Columbia Banking common stock. He also has 4,679 Restricted Stock Units outstanding. These figures give a clearer view of his ongoing equity stake following the vesting and associated tax-withholding disposition.

Was this COLB insider transaction an open-market buy or sell?

The filing shows a derivative exercise and tax-withholding disposition, not open-market trades. Moore acquired shares through RSU conversion and then had 376 shares withheld to cover tax or exercise obligations, a common administrative step in equity compensation rather than discretionary buying or selling.