William J. Peters - 09 Mar 2026 Form 4 Insider Report for Amphastar Pharmaceuticals, Inc. (AMPH)

Role: CFO, EVP & TREASURER, Director
Signature: /s/ William J. Peters
Issuer symbol: AMPH
Transactions as of: 09 Mar 2026
Net transactions value: $0
Form type: 4
Filing time: 11 Mar 2026, 21:29:26 UTC
Previous filing: 10 Mar 2026
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
PETERS WILLIAM J	CFO, EVP & TREASURER, Director	C/O AMPHASTAR PHARMACEUTICALS, INC., 11570 6TH STREET, RANCHO CUCAMONGA	/s/ William J. Peters	11 Mar 2026	0001263136

Transactions Table

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Ownership	Footnotes
transaction	AMPH	Common Stock	Award		+58,693	+48%	$0.000000^*	180,333	09 Mar 2026	Direct	F1
transaction	AMPH	Common Stock	Tax liability		-3,297	-1.8%	$18.91^*	177,036	10 Mar 2026	Direct	F2

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	AMPH	Employee Stock Option (right to buy)	Award		+121,071		$0.000000^*	121,071	09 Mar 2026	Common Stock	121,071	$19.21	Direct	F3

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The reported shares are represented by restricted stock units, or RSUs, which vest in four equal annual installments beginning on March 9, 2027.
F2	The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of RSUs.
F3	The shares subject to the option vest in four equal annual installments beginning on March 9, 2027.