Tax-withholding share disposition reported by Columbia Banking System (COLB) EVP

Rhea-AI Filing Summary

Columbia Banking System executive Drew K. Anderson reported a tax-related share disposition under a Form 4. On the transaction date, 1,808 shares of common stock were delivered at $28.45 per share to satisfy a tax obligation, leaving 20,678 common shares held directly after the transaction.

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^*

Anderson Drew K

(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 Admin 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		1,808	D	$28.45	20,678	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 Drew K. Anderson report for COLB?

Drew K. Anderson reported a tax-withholding disposition of 1,808 shares of Columbia Banking System common stock. The shares were delivered to cover obligations rather than sold on the open market, as indicated by transaction code F and its tax-liability description.

How many COLB shares did Drew K. Anderson dispose of in the Form 4 filing?

The Form 4 shows a disposition of 1,808 Columbia Banking System common shares. These shares were used to pay a tax liability, reflected by transaction code F, which denotes payment of exercise price or tax obligations by delivering securities.

What price per share was used in Drew K. Anderson’s COLB tax-withholding transaction?

The reported transaction used a price of $28.45 per Columbia Banking System common share. This price applies to the 1,808 shares delivered in the tax-withholding disposition, as disclosed in the Form 4 insider filing data.

How many COLB shares does Drew K. Anderson hold after the reported transaction?

After the tax-withholding disposition, Drew K. Anderson directly holds 20,678 Columbia Banking System common shares. This post-transaction balance is explicitly listed as the total number of shares owned following the Form 4 transaction.

Does the COLB Form 4 indicate an open-market sale by Drew K. Anderson?

The Form 4 indicates a tax-withholding disposition, not an open-market sale. Transaction code F and its description show the 1,808 shares were delivered to satisfy a tax liability rather than being sold through a market transaction.

What is Drew K. Anderson’s role at Columbia Banking System in this Form 4?

In this Form 4, Drew K. Anderson is identified as an officer of Columbia Banking System, serving as EVP Chief Admin Officer. The reported tax-withholding disposition relates to his holdings of the company’s common stock.