[Form 4] Columbia Banking Systems Inc Insider Trading Activity

Rhea-AI Filing Summary

Jaynie M. Studenmund, a director of Columbia Banking System, Inc. (COLB), reported acquisition of Columbia common stock related to Columbia's acquisition of Pacific Premier Bancorp, Inc. Pursuant to the merger, each Pacific Premier share held by the reporting person converted into the right to receive 0.9150 shares of Columbia common stock, with fractional shares paid in cash. The reporter acquired 15,653 shares directly and 3,843 shares indirectly (via a Morgan Stanley IRA) on 08/31/2025, and an additional 2,205 restricted shares were acquired on 09/02/2025 that vest in full on 05/15/2026. The form notes closing prices on 08/29/2025: Columbia $26.77 and Pacific Premier $24.49.

Positive

• Merger consideration received in stock: Reporting person acquired Columbia shares under the Pacific Premier acquisition at a 0.9150 conversion ratio
• Clear disclosure of ownership forms: Filing separates direct, indirect (Morgan Stanley IRA), and restricted stock with a specific vesting date of 05/15/2026

Negative

• None.

Insights

M&A Specialist

TL;DR: Share conversion from Pacific Premier to Columbia reflects merger consideration delivered as Columbia stock, with restricted awards outstanding.

The Form 4 documents a share-for-share conversion under Columbia's acquisition of Pacific Premier, using a fixed conversion ratio of 0.9150 Columbia shares per Pacific Premier share and cash for fractional holdings. The reporting person received 15,653 direct shares and 3,843 indirect shares on the merger closing date, plus 2,205 restricted shares that vest on May 15, 2026. The filing simply reports the mechanics and post-transaction holdings; it contains no valuation adjustments beyond reported closing prices on August 29, 2025.

Corporate Governance Expert

TL;DR: Routine insider reporting of merger-related equity issuance and a director's indirect holdings via an IRA; disclosure appears complete.

The filing identifies the reporting person as a director and shows both direct and indirect beneficial ownership arising from the merger and a separate restricted stock grant. It specifies the indirect ownership vehicle (Morgan Stanley IRA) and the vesting date for restricted shares. The signature is by an attorney-in-fact, consistent with delegated filing authority. There are no statements of sale, loans, or other peculiar governance issues disclosed here.

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^*

STUDENMUND JAYNIE M

(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
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
08/31/2025

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	08/31/2025		A		15,653(1)	A	$0(1)	15,653	D
Common Stock	08/31/2025		A		3,843(1)	A	$0(1)	3,843	I	By Morgan Stanley IRA
Common Stock	09/02/2025		A		2,205(2)	A	$0(2)	17,858	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:

1. 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.

2. Restricted stock awards that vest in their entirety on May 15, 2026.

Remarks:

	/s/ Lisa M. White, Attorney-in-fact	09/03/2025
	** 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 did Jaynie M. Studenmund report on Form 4 for COLB?

She reported acquisitions of Columbia common stock related to the Columbia acquisition of Pacific Premier: 15,653 direct shares, 3,843 indirect shares, and 2,205 restricted shares.

Why were the shares acquired on 08/31/2025?

They were acquired pursuant to the merger in which Pacific Premier shares converted into Columbia shares at a ratio of 0.9150 per Pacific Premier share.

How many total Columbia shares does the report show after the transactions?

The form shows 17,858 shares beneficially owned following the reported transactions (direct ownership figure reported after the last acquisition).

Are any of the reported shares subject to vesting?

Yes. The filing discloses 2,205 restricted stock awards that vest in full on 05/15/2026.

What prices are referenced in the Form 4?

Closing prices on August 29, 2025 are cited: Columbia common stock $26.77 and Pacific Premier common stock $24.49; fractional shares were paid in cash.