Equity awards and tax withholding for Amphastar Pharmaceuticals (AMPH) insiders

Rhea-AI Filing Summary

Amphastar Pharmaceuticals insiders reported routine equity compensation and related tax withholding. CEO Jack Y. Zhang and COO Mary Z. Luo, who are also major shareholders and directors, received grants of restricted stock units (RSUs) and employee stock options tied to common stock. The RSUs, totaling 180,504 shares held directly and 72,462 shares held indirectly, vest in four equal annual installments beginning on March 9, 2027. They also received employee stock options for 372,338 shares held directly and 149,472 shares held indirectly, with a $19.21 exercise price and the same four-year vesting schedule. In connection with RSU vesting, 14,785 directly held shares and 4,395 indirectly held shares of common stock were withheld at $18.91 per share to cover tax liabilities, a non‑market transaction. Following these updates, reported holdings include 3,014,621 shares of common stock held directly, 1,252,428 shares held indirectly, and 6,827,679 additional shares held indirectly through Applied Physics and Chemistry Laboratories, Inc. and a related trust.

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

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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 for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Zhang Jack Y.

(Last) (First) (Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC.

11570 6TH STREET

(Street)

RANCHO CUCAMONGA CA 91730

(City) (State) (Zip)

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

3. Date of Earliest Transaction (Month/Day/Year)
03/09/2026

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	03/09/2026		A		180,504(1)	A	$0	3,014,621	D
Common Stock	03/10/2026		F		14,785(2)	D	$18.91	2,999,836	D
Common Stock	03/09/2026		A		72,462(1)	A	$0	1,252,428	I	See footnote(3)
Common Stock	03/10/2026		F		4,395(2)	D	$18.91	1,248,033	I	See footnote(3)
Common Stock								6,827,679	I	See footnote(4)

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
Employee Stock Option (right to buy)	$19.21	03/09/2026		A		372,338		(5)	03/09/2036	Common Stock	372,338	$0	372,338	D
Employee Stock Option (right to buy)	$19.21	03/09/2026		A		149,472		(5)	03/09/2036	Common Stock	149,472	$0	149,472	I	See footnote(3)

1. Name and Address of Reporting Person^*

Zhang Jack Y.

(Last) (First) (Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC.

11570 6TH STREET

(Street)

RANCHO CUCAMONGA CA 91730

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
X	Officer (give title below)		Other (specify below)
	CEO & CHIEF SCIENTIFIC OFFICER

1. Name and Address of Reporting Person^*

Luo Mary Z.

(Last) (First) (Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC.

11570 6TH STREET

(Street)

RANCHO CUCAMONGA CA 91730

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director	X	10% Owner
X	Officer (give title below)		Other (specify below)
	COO, Chief Scientist, Chairman

Explanation of Responses:

1. The reported shares are represented by restricted stock units, or RSUs, which vest in four equal annual installments beginning on March 9, 2027.

2. The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of RSUs.

3. The securities are held of record by Mary Z. Luo. The reporting persons are husband and wife.

4. 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.

5. The shares subject to the option vest in four equal annual installments beginning on March 9, 2027.

	/s/ Eva Wen, by power of attorney for Jack Y. Zhang	03/11/2026
	/s/ Eva Wen, by power of attorney for Mary Z. Luo	03/11/2026
	** Signature of Reporting Person	Date
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FAQ

What insider transactions were reported for Amphastar Pharmaceuticals (AMPH)?

Amphastar insiders reported grants of RSUs and stock options plus share withholding for taxes. Awards increased equity exposure, while 19,180 common shares were withheld at $18.91 to cover RSU-related tax liabilities, reflecting routine, non-market compensation activity rather than open-market buying or selling.

How many RSUs did Amphastar (AMPH) insiders receive and when do they vest?

Reporting persons received 180,504 directly held and 72,462 indirectly held RSUs. These restricted stock units vest in four equal annual installments beginning on March 9, 2027, creating a multi‑year equity incentive structure tied to continued service and long‑term alignment with shareholders.

What stock options were granted to Amphastar (AMPH) insiders in this Form 4?

Insiders were granted employee stock options on 372,338 underlying shares held directly and 149,472 held indirectly. These options have a $19.21 exercise price, expire in 2036, and vest in four equal annual installments starting March 9, 2027, reinforcing long‑term compensation incentives.

Why were Amphastar (AMPH) shares disposed of in this insider report?

The reported dispositions were tax-withholding events, not open-market sales. A total of 14,785 directly held and 4,395 indirectly held common shares were withheld at $18.91 per share to satisfy tax liabilities triggered by RSU vesting, a standard administrative mechanism for equity awards.

What are the post-transaction share holdings reported for Amphastar (AMPH) insiders?

Post-transaction entries show 3,014,621 common shares held directly, 1,252,428 shares held indirectly, and 6,827,679 additional indirect shares held through Applied Physics and Chemistry Laboratories, Inc. and a related trust, underscoring substantial continuing ownership by the reporting persons and affiliated entities.

Do the Amphastar (AMPH) insider transactions indicate open-market buying or selling?

No open-market purchases or sales are reported. Activity consists of equity grants—RSUs and stock options—and share withholding to cover taxes at $18.91 per share. These are routine compensation and administrative events, not discretionary trades that change market float directly.