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

1. Name and Address of Reporting Person* Merck & Co., Inc. (Last) (First) (Middle) 126 EAST LINCOLN AVENUE (Street) RAHWAY NJ 07065 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol Harpoon Therapeutics, Inc. [ HARP ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 03/11/2024
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X 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, par value $0.0001	03/11/2024		P		21,397,205(1)(2)	A	$23	1,000(1)(2)	I	See Footnote(1)(2)

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

1. Name and Address of Reporting Person* Merck & Co., Inc. (Last) (First) (Middle) 126 EAST LINCOLN AVENUE (Street) RAHWAY NJ 07065 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* MERCK SHARP & DOHME LLC (Last) (First) (Middle) 126 EAST LINCOLN AVENUE (Street) RAHWAY NJ 07065 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. Pursuant to the Agreement and Plan of Merger, dated as of January 7, 2024 by and among Merck Sharp & Dohme LLC, a wholly owned subsidiary of Merck & Co. Inc. ("Parent"), Hawaii Merger Sub, Inc., a wholly owned subsidiary of Merck Sharp & Dohme LLC ("Merger Sub"), and Harpoon Therapeutics, Inc. ("Harpoon"), Merger Sub merged with and into Harpoon (the "Merger") on March 11, 2024. Upon completion of the Merger, each share of common stock of Harpoon that was issued and outstanding immediately prior to the effective time of the Merger was cancelled, and each share of common stock of Merger Sub was converted into one share of common stock of the surviving corporation.

2. (Continued from footnote 1) Consequently, upon the consummation of the Merger on March 11, 2024, Parent became the direct beneficial owner of 1,000 shares of common stock of the surviving corporation, representing 100% of the issued and outstanding shares of common stock of the surviving corporation. Merck & Co., Inc. is the indirect beneficial owner of such shares.

	/s/ Kelly E.W. Grez, Kelly E.W. Grez, Corporate Secretary	03/11/2024
	/s/ Anthony Wildasin, Anthony Wildasin, Assistant Secretary	03/11/2024
	** 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.