Columbia Banking director reports 32,931 shares

Newly reported Columbia Banking System director Simone Lagomarsino discloses indirect ownership of common stock through a family trust and an IRA.

Rhea-AI Filing Summary

COLUMBIA BANKING SYSTEM, INC. (COLB) director Simone Lagomarsino filed an initial ownership report showing indirect holdings of the company’s Common Stock. The filing lists 32,931 shares held indirectly through a family trust and an additional 7 shares held indirectly through an IRA as of September 1, 2026.

Insider Trade Summary

2 transactions reported

Mixed 2 txns

Insider LAGOMARSINO SIMONE

Role Director

Type	Security	Shares	Price	Value
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 32,931 shares (Indirect, by family trust); Common Stock — 7 shares (Indirect, by IRA)

Key Figures

Indirect shares by family trust: 32,931 shares Indirect shares by IRA: 7 shares Number of holding entries: 2 entries

3 metrics

Indirect shares by family trust 32,931 shares Common Stock held indirectly by family trust following the reported holdings as of September 1, 2026

Indirect shares by IRA 7 shares Common Stock held indirectly by IRA following the reported holdings as of September 1, 2026

Number of holding entries 2 entries Two indirect Common Stock holding lines reported (family trust and IRA)

Key Terms

indirect, family trust, IRA

3 terms

indirect financial

"The filing lists indirect holdings of Common Stock by family trust and by IRA"

family trust financial

"Total shares following transaction were held indirect by family trust"

IRA financial

"Total shares following transaction were held indirect by IRA"

An individual retirement account (IRA) is a savings account designed to help people put aside money for their retirement, often with tax advantages that encourage long-term savings. It matters to investors because it can grow over time, providing financial security later in life, and offers benefits that can reduce current taxes or allow investments to compound more effectively.

FAQ

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

What does the Form 3 filing report for COLB director Simone Lagomarsino?

It reports Simone Lagomarsino’s initial ownership in COLUMBIA BANKING SYSTEM, INC. common stock, consisting of indirect holdings through a family trust and an IRA as of September 1, 2026.

How many COLB shares are held through the family trust?

The filing shows 32,931 shares of COLUMBIA BANKING SYSTEM, INC. common stock held indirectly by Simone Lagomarsino by family trust as of September 1, 2026.

How many COLB shares are held through the IRA?

The Form 3 indicates that 7 shares of COLUMBIA BANKING SYSTEM, INC. common stock are held indirectly by Simone Lagomarsino by IRA as of September 1, 2026.

Does the Form 3 for COLB show any recent stock purchases or sales?

No. The entry is an initial ownership report and lists holding positions only, with no reported transaction code or share amounts acquired or disposed on September 1, 2026.

Are Simone Lagomarsino’s COLB holdings direct or indirect?

All reported positions are indirect. The filing states 32,931 shares held indirectly by a family trust and 7 shares held indirectly by an IRA.

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

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Available on EDGAR 09/02/2026 - 04:38 PM EDT Accepted by SEC EDGAR 09/02/2026 - 04:37 PM EDT Learn about SEC filing dates

SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

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:			3235-0104
Estimated average burden
hours per response:			0.5

1. Name and Address of Reporting Person^*

LAGOMARSINO SIMONE

(Last) (First) (Middle)

C/O COLUMBIA BANKING SYSTEM, INC.

1301 A STREET

(Street)

TACOMA WASHINGTON 98402

(City) (State) (Zip)

UNITED STATES

(Country)

2. Date of Event Requiring Statement (Month/Day/Year)
09/01/2026

3. Issuer Name and Ticker or Trading Symbol
COLUMBIA BANKING SYSTEM, INC. [ COLB ]

3a. Foreign Trading Symbol

5. If Amendment, Date of Original Filed (Month/Day/Year)

4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	32,931	I	by family trust
Common Stock	7	I	by IRA

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

Remarks:

	/s/ Kumi Yamamoto Baruffi, Attorney-in-fact	09/02/2026
	** 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 5 (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.
* Form 3: SEC 1473 (03-26)