Luis Machuca - 03 Dec 2025 Form 4 Insider Report for COLUMBIA BANKING SYSTEM, INC. (COLB)

Role: Director
Signature: /s/ Andrea M. Newburn, Attorney-in-fact
Issuer symbol: COLB
Transactions as of: 03 Dec 2025
Net transactions value: +$19,320
Form type: 4
Filing time: 05 Feb 2026, 19:07:27 UTC
Previous filing: 06 Nov 2025
Next filing: 02 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/ Andrea M. Newburn, Attorney-in-fact	05 Feb 2026	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	$1,831	+65	+0.14%	$28.17	47,182	03 Dec 2025	Common	65		Deferred Compensation	F1
transaction	COLB	Deferred Compensation Phantom Stock	Award	$17,489	+562	+1.2%	$31.12	47,744	04 Feb 2026	Common	562		Deferred Compensation	F2

* 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 the result of a transaction by the plan administrator that the reporting person did not request and that they were not aware of at the time of the transaction. The phantom stock will be paid in accordance with the terms of the deferred compensation plan following the end of the reporting person's employment with the Registrant.
F2	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 the end of the reporting person's employment with the Registrant.

Content

The deferred compensation plan phantom stock was accrued under the Registrant's deferred compensation plan and the result of a transaction by the plan administrator that the reporting person did not request and that they were not aware of at the time of the transaction. The phantom stock will be paid in accordance with the terms of the deferred compensation plan following the end of the reporting person's employment with the Registrant.

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 the end of the reporting person's employment with the Registrant.