Sec Form 4 Filing - Bucher James B @ Harpoon Therapeutics, Inc. - 2024-03-11

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 Bucher James B 2. Issuer Name and Ticker or Trading Symbol Harpoon Therapeutics, Inc. [ HARP] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director _____ 10% Owner X __ Officer (give title below) _____ Other (specify below) Chief Legal Officer (Last) (First) (Middle) C/O HARPOON THERAPEUTICS, INC., 611 GATEWAY BOULEVARD, SUITE 400 3. Date of Earliest Transaction (MM/DD/YY) 03/11/2024 (Street) SOUTH SAN FRANCISCO, CA94080 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

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 Employee Stock Option (Right to Buy) $ 11.3 03/11/2024 D( 1 ) 110,000 ( 2 )( 3 ) ( 2 )( 3 ) Common Stock 110,000 ( 2 ) ( 3 ) 0 D

Reporting Owners Reporting Owner Name / Ad dress Relationships Director 10% Owner Officer Other Bucher James B C/O HARPOON THERAPEUTICS, INC. 611 GATEWAY BOULEVARD, SUITE 400 SOUTH SAN FRANCISCO, CA94080 Chief Legal Officer Signatures /s/ James B. Bucher 03/11/2024 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This Form 4 reports securities disposed of pursuant to the terms of the Agreement and Plan of Merger (the "Merger Agreement"), dated as of January 7, 2024, by and among the Issuer, Merck Sharp & Dohme LLC, a New Jersey limited liability company ("Parent"), and Hawaii Merger Sub, Inc., a Delaware corporation and a wholly owned subsidiary of Parent ("Merger Sub"), pursuant to which Merger Sub merged with and into the Issuer on March 11, 2024, with the Issuer surviving the merger as a wholly owned subsidiary of Parent (the "Merger"). ( 2 )Pursuant to the terms of the Merger Agreement, immediately prior to the effective time of the Merger (the "Effective Time"), each outstanding option to purchase shares of the Issuer's common stock, par value $0.0001 per share ("Common Stock") granted under an Issuer equity plan (each, a "Stock Option"), to the extent unvested, became fully vested and exercisable effective immediately prior to, and contingent upon, the Effective Time. Pursuant to the terms of the Merger Agreement, at the Effective Time, (i) each Stock Option that was outstanding and unexercised immediately prior to the Effective Time and that had a per share exercise price that is less than $23.00 in cash per share of Common Stock, without interest (the "Common Stock Merger Consideration" and each such Stock Option, an ( 3 )(Continued from footnote 2) "In the Money Option") was cancelled in exchange for the right to receive an amount in cash (without interest and subject to any applicable withholding or other taxes) equal to the product of (1) the total number of shares of Common Stock subject to such Stock Option immediately prior to the Effective Time and (2) the excess of the Common Stock Merger Consideration over the per share exercise price payable for such Stock Option immediately prior to the Effective Time and (ii) each Stock Option other than an In the Money Option then outstanding and unexercised was cancelled with no consideration payable in respect thereof.

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).

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