Steven R. Gardner - Aug 31, 2025 Form 4 Insider Report for COLUMBIA BANKING SYSTEM, INC. (COLB)

Role: Director
Signature: /s/ Lisa M. White, Attorney-in-fact
Stock symbol: COLB
Transactions as of: Aug 31, 2025
Transactions value $: $0
Form type: 4
Date filed: 9/3/2025, 09:47 PM
Previous filing: Aug 27, 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
GARDNER STEVEN R	Director	C/O COLUMBIA BANKING SYSTEM, INC., 1301 A STREET, TACOMA	/s/ Lisa M. White, Attorney-in-fact	2025-09-03	0001267342

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	COLB	Common Stock	Award	$0	+246K		$0.00	246K	Aug 31, 2025	Direct	F1
transaction	COLB	Common Stock	Award	$0	+338K		$0.00	338K	Aug 31, 2025	By The Gardner Family Trust	F1

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

Explanation of Responses:

Id	Content
F1	Acquired in connection with Columbia Banking System, Inc.'s ("Columbia") acquisition of Pacific Premier Bancorp, Inc. ("Pacific Premier") on August 31, 2025. Pursuant to the merger agreement, each issued and outstanding share of Pacific Premier common stock held by the reporting person was converted into the right to receive 0.9150 of a share of Columbia common stock. All fractional share holdings were paid in cash. On August 29, 2025, the closing price of Columbia common stock was $26.77, and the closing price of Pacific Premier common stock was $24.49.

Content

Acquired in connection with Columbia Banking System, Inc.'s ("Columbia") acquisition of Pacific Premier Bancorp, Inc. ("Pacific Premier") on August 31, 2025. Pursuant to the merger agreement, each issued and outstanding share of Pacific Premier common stock held by the reporting person was converted into the right to receive 0.9150 of a share of Columbia common stock. All fractional share holdings were paid in cash. On August 29, 2025, the closing price of Columbia common stock was $26.77, and the closing price of Pacific Premier common stock was $24.49.