Columbia Banking (NASDAQ: COLB) EVP disposes shares for tax withholding

Rhea-AI Filing Summary

Columbia Banking System EVP and Chief Accounting Officer Lakely Brock reported a tax-related share disposition. On this Form 4, Brock transferred 391 shares of common stock on March 1, 2026 at $28.45 per share to cover tax liabilities, a non-open-market transaction coded as a tax-withholding disposition. After this transaction, Brock directly owns 10,469 common shares.

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^*

Lakely Brock

(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 Accounting Officer

3. Date of Earliest Transaction (Month/Day/Year)
03/01/2026

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	03/01/2026		F		391	D	$28.45	10,469	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

Explanation of Responses:

Remarks:

	/s/ Andrea M. Newburn, Attorney-in-fact	03/02/2026
	** Signature of Reporting Person	Date
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.

FAQ

What insider transaction did COLB executive Lakely Brock report on this Form 4?

Lakely Brock reported a tax-withholding disposition of 391 Columbia Banking System common shares. The transaction used shares, valued at $28.45 each, to satisfy tax obligations rather than representing an open-market sale. This is a routine administrative event for equity compensation.

How many COLB shares did Lakely Brock dispose of for tax withholding?

Lakely Brock disposed of 391 Columbia Banking System common shares for tax-withholding purposes. The shares were valued at $28.45 each and were used to cover tax liabilities arising from equity compensation, rather than being sold in the open market to third-party buyers.

What is Lakely Brock’s COLB share ownership after this reported transaction?

After the reported tax-withholding disposition, Lakely Brock directly owns 10,469 Columbia Banking System common shares. This post-transaction balance reflects the remaining holdings following the use of 391 shares to satisfy tax obligations tied to stock-based compensation awards.

Was the COLB Form 4 transaction an open-market sale of shares?

The transaction was not an open-market sale; it was a tax-withholding disposition. Columbia Banking System executive Lakely Brock used 391 shares, at $28.45 each, to pay tax liabilities, which is commonly associated with the settlement of equity compensation awards.

What does transaction code F mean in the COLB Form 4 filing?

Transaction code F in this Columbia Banking System Form 4 indicates payment of a tax liability by delivering securities. Here, 391 shares of common stock were withheld at $28.45 per share to cover taxes related to equity compensation for executive Lakely Brock.