Sec Form 4 Filing - Seath Matthew Douglas @ TIMBERLAND BANCORP INC - 2026-07-31

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Seath Matthew Douglas 2. Issuer Name and Ticker or Trading Symbol TIMBERLAND BANCORP INC [ TSBK] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Risk Officer/EVP (Last) (First) (Middle) 624 SIMPSON AVENUE 3. Date of Earliest Transaction (MM/DD/YY) 07/31/2026 (Street) HOQUIAM, WA98550 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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, $.01 par value per share 07/31/2026 M 800 A $ 31.8 3,955 D Common Stock, $.01 par value per share 07/31/2026 M 800 A $ 27.14 4,755 D Common Stock, $.01 par value per share 07/31/2026 M 800 A $ 28.23 5,555 D Common Stock, $.01 par value per share 07/31/2026 M 600 A $ 27.4 6,155 D Common Stock, $.01 par value per share 07/31/2026 S 3,000 D $ 44.75 3,155 D Common Stock, $.01 par value per share 2,155 I By KSOP ( 1 )

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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 Stock Options (Right to Buy) $ 31.8 07/31/2026 M 800 09/25/2023 09/25/2028 Common Stock 800 $ 0 2,800 D Stock Options (Right to Buy) $ 27.14 07/31/2026 M 800 09/24/2024 09/24/2029 Common Stock 800 $ 0 2,000 D Stock Options (Right to Buy) $ 28.23 07/31/2026 M 800 09/28/2026( 2 ) 09/28/2031 Common Stock 800 $ 0 1,200 D Stock Options (Right to Buy) $ 27.4 07/31/2026 M 600 09/27/2027( 2 ) 09/27/2032 Common Stock 600 $ 0 600 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Seath Matthew Douglas 624 SIMPSON AVENUE HOQUIAM, WA98550 Chief Risk Officer/EVP Signatures /s/Cheryl Parks, Power of Attorney for Matthew Douglas Seath 08/03/2026 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents shares held in the Timberland Bank Employee Stock Ownership and 401(k) Plan ("KSOP") ( 2 )Represents date options will be fully vested

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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