Columbia Banking EVP exercises RSUs, covers taxes

Columbia Banking System EVP Aaron James Deer exercised restricted stock units into common shares as part of his compensation.

Rhea-AI Filing Summary

Columbia Banking System EVP Aaron James Deer exercised restricted stock units into common shares as part of his compensation. On March 13, 2026 he converted 1,567 restricted stock units into common stock, with 617 common shares withheld at $26.23 per share to cover tax obligations, rather than sold in the market.

Following these transactions, he directly owns 41,875 common shares and 7,133 restricted stock units. The RSUs convert into common stock on a one-for-one basis. They stem from a 4,699-unit grant made on February 25, 2025, vesting in three annual installments beginning March 13, 2026.

Insider Trade Summary

1,567 shares exercised/converted

Exercise 3 txns

Insider Deer Aaron James

Role EVP Chief Strategy/Innov Offcr

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Unit	1,567	$0.00	$0.00
Exercise	Common Stock	1,567	$26.23	$41K
Exercise Price or Tax Liability	Common Stock	617	$26.23	$16K

Holdings After Transaction: Restricted Stock Unit — 7,133 contracts (Direct); Common Stock — 41,875 shares (Direct)

Footnotes (1)

1. F1. Restricted Stock Units convert into common stock on a one-for-one basis. On February 25, 2025, the reporting person was granted 4,699 Restricted Stock Units, which vest in three annual installments beginning on March 13, 2026.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transaction did COLB executive Aaron James Deer report?

Executive Aaron James Deer reported exercising 1,567 restricted stock units into common stock. The transaction occurred on March 13, 2026, as part of a previously granted equity award that vests over time, reflecting routine compensation rather than a discretionary open-market trade.

Did the COLB EVP buy or sell common stock in the open market?

He did not conduct an open-market purchase or sale. Shares were acquired through exercising restricted stock units, and 617 common shares were withheld at $26.23 per share solely to satisfy tax obligations, a standard non-market mechanism in equity compensation programs.

How many Columbia Banking (COLB) shares does the EVP hold after this Form 4?

After the reported transactions, he directly holds 41,875 shares of common stock. He also has 7,133 restricted stock units outstanding, which are scheduled to convert into common shares on a one-for-one basis as they vest under the original award terms.

What is the origin of the restricted stock units exercised by COLB’s EVP?

The restricted stock units come from a 4,699-unit grant awarded on February 25, 2025. This grant vests in three equal annual installments beginning March 13, 2026, and the units convert into Columbia Banking common stock on a one-for-one basis upon vesting.

Is the COLB insider transaction mainly an option exercise or a tax-related event?

The transaction is primarily an equity award vesting and exercise, combined with a tax-related share withholding. 1,567 restricted stock units converted into common shares, and 617 of those shares were withheld to cover tax liabilities, which does not represent a market sale.

What was the price used for COLB shares withheld for taxes?

The shares withheld for taxes were valued at $26.23 per share. A total of 617 common shares were retained by the issuer at this price to satisfy the executive’s tax obligations related to the restricted stock unit conversion event.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/17/2026 - 12:00 AM Learn about SEC filing dates

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

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

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^*

Deer Aaron James

(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 Strategy/Innov Offcr

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		1,567	A	$26.23	42,492	D
Common Stock	03/13/2026		F		617	D	$26.23	41,875	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			1,567	(1)	(1)	Common Stock	1,567	$0	7,133	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 4,699 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).
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