Columbia Banking (NASDAQ: COLB) CEO exercises RSUs, boosts holdings after tax withholding

Rhea-AI Filing Summary

Columbia Banking System Chair, CEO and President Clint Stein exercised 18,171 restricted stock units into common shares and had part of the shares withheld for taxes. The restricted stock units converted one-for-one into common stock, and the associated common stock transaction was valued at $26.23 per share.

Of the 18,171 common shares tied to this vesting, 7,151 shares were withheld to satisfy tax obligations, leaving a net increase of 11,020 shares in his direct holdings. After these compensation-related transactions, Stein directly holds 151,584 shares of Columbia Banking System common stock.

The restricted stock units come from a grant of 54,511 units awarded on February 25, 2025, which vests in three equal annual installments beginning on March 13, 2026. This filing reflects the first vesting installment and related tax withholding rather than an open-market purchase or sale.

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^*

Stein Clint

(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)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chair, CEO, President

3. Date of Earliest Transaction (Month/Day/Year)
03/13/2026

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	03/13/2026		M		18,171	A	$26.23	158,735	D
Common Stock	03/13/2026		F		7,151	D	$26.23	151,584	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
Restricted Stock Unit	(1)	03/13/2026		M			18,171	(1)	(1)	Common Stock	18,171	$0	166,984	D

Explanation of Responses:

1. Restricted Stock Units convert into common stock on a one-for-one basis. On February 25, 2025, the reporting person was granted 54,511 Restricted Stock Units, which vest in three annual installments beginning on March 13, 2026.

Remarks:

	/s/ Andrea M. Newburn, Attorney-in-fact	03/17/2026
	** 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.
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FAQ

What insider transaction did COLB CEO Clint Stein report?

Clint Stein reported exercising 18,171 restricted stock units into common shares. These units vested as part of his equity compensation, increasing his direct ownership in Columbia Banking System while some shares were withheld to cover related tax obligations.

How many COLB shares does Clint Stein hold after this Form 4?

After the reported transactions, Clint Stein directly holds 151,584 shares of Columbia Banking System common stock. This reflects the net result of his restricted stock unit vesting and the related tax withholding disposition on March 13, 2026.

Were any of Clint Stein’s COLB transactions open-market buys or sells?

No, the transactions reflect an exercise of restricted stock units and tax withholding, not open-market trades. Shares were acquired through vesting and a portion was withheld to satisfy tax obligations rather than being sold on the open market.

What is the value reference for the COLB shares in this filing?

The common stock transactions are reported at $26.23 per share. This price is used in the Form 4 for calculating the value of the vested shares and the portion withheld to cover Stein’s tax liability on the equity compensation event.

What is the size of Clint Stein’s restricted stock unit grant at COLB?

Stein was granted 54,511 restricted stock units on February 25, 2025. These units vest in three equal annual installments starting March 13, 2026, and each vested unit converts into one share of Columbia Banking System common stock upon settlement.

How many COLB shares were withheld for Clint Stein’s taxes?

A total of 7,151 common shares were withheld to satisfy tax obligations. These shares come from the 18,171 units that vested and converted, leaving the remaining shares to increase Stein’s direct ownership position in Columbia Banking System.