FORM 4
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 that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.         
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
                                                                                  
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OMB Number: 3235-0287
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940
                      

1. Name and Address of Reporting Person *

Zhang Jack Y.
2. Issuer Name and Ticker or Trading Symbol

Amphastar Pharmaceuticals, Inc. [ AMPH ]
5. Relationship of Reporting Person(s) to Issuer (Check all applicable)

__X__ Director                    __X__ 10% Owner
__X__ Officer (give title below)    _____ Other (specify below)
CEO & CHIEF SCIENTIFIC OFFICER
(Last)          (First)          (Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC., 11570 6TH STREET
3. Date of Earliest Transaction (MM/DD/YYYY)

6/10/2024
(Street)

RANCHO CUCAMONGA, CA 91730
4. If Amendment, Date Original Filed (MM/DD/YYYY)

 
6. Individual or Joint/Group Filing (Check Applicable Line)

___ Form filed by One Reporting Person
_ X _ 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. Trans. Date 2A. Deemed Execution Date, if any 3. Trans. 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 6/10/2024  M  100,000 A$14.69 2,533,554 D 
 
Common Stock         1,229,756 I See footnote (1)
Common Stock         6,827,679 I See footnote (2)

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security
(Instr. 3)
2. Conversion or Exercise Price of Derivative Security3. Trans. Date3A. Deemed Execution Date, if any4. Trans. Code
(Instr. 8)
5. Number of Derivative Securities Acquired (A) or Disposed of (D)
(Instr. 3, 4 and 5)
6. Date Exercisable and Expiration Date7. 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 of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Employee Stock Option (right to buy) $14.69 6/10/2024  M     100,000   (3)3/16/2025 Common Stock 100,000 $0 390,477 D 
 

Explanation of Responses:
(1) The securities are held of record by Mary Z. Luo. The reporting persons are husband and wife.
(2) The shares are held of record by Applied Physics and Chemistry Laboratories, Inc., of which the reporting persons and The Bill Luobei Zhang 2004 Irrevocable Trust are the sole owners.
(3) Shares subject to the option are fully vested and immediately exercisable.

Reporting Owners
Reporting Owner Name / Address
Relationships
Director10% OwnerOfficerOther
Zhang Jack Y.
C/O AMPHASTAR PHARMACEUTICALS, INC.
11570 6TH STREET
RANCHO CUCAMONGA, CA 91730
XXCEO & CHIEF SCIENTIFIC OFFICER
Luo Mary Z.
C/O AMPHASTAR PHARMACEUTICALS, INC.
11570 6TH STREET
RANCHO CUCAMONGA, CA 91730
XXCOO, Chief Scientist, Chairman

Signatures
/s/ Eva Wen, by power of attorney for Jack Y. Zhang6/11/2024
**Signature of Reporting PersonDate

/s/ Eva Wen, by power of attorney for Mary Z. Luo6/11/2024
**Signature of Reporting PersonDate


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 control number.