Luis Machuca - 05 Nov 2025 Form 4 Insider Report for COLUMBIA BANKING SYSTEM, INC. (COLB)

Role: Director
Signature: /s/ Lisa M. White, Attorney-in-fact
Issuer symbol: COLB
Transactions as of: 05 Nov 2025
Net transactions value: +$16,726
Form type: 4
Filing time: 06 Nov 2025, 16:36:16 UTC
Previous filing: 08 Oct 2025
Next filing: 05 Feb 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
MACHUCA LUIS	Director	C/O COLUMBIA BANKING SYSTEM, INC., 1301 A STREET, TACOMA	/s/ Lisa M. White, Attorney-in-fact	06 Nov 2025	0001133099

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	COLB	Deferred Compensation Phantom Stock	Award	$16,726	+630	+1.4%	$26.55	47,117	05 Nov 2025	Common	630		Deferred Compensation	F1

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The deferred compensation plan phantom stock was accrued under the Registrant's deferred compensation plan and will be paid in accordance with the terms of the deferred compensation plan following end of the reporting person's employment with the Registrant.