Amphastar (AMPH) CFO granted RSUs, stock options and withholds shares for taxes

Rhea-AI Filing Summary

Amphastar Pharmaceuticals CFO William J. Peters reported equity compensation and related tax withholding transactions. On March 9, 2026, he received 58,693 shares of Common Stock in the form of restricted stock units that vest in four equal annual installments beginning on March 9, 2027.

On the same date, he was granted an employee stock option covering 121,071 shares of Common Stock at an exercise price of $19.21 per share, expiring in 2036, also vesting in four equal annual installments beginning on March 9, 2027. On March 10, 2026, 3,297 shares of Common Stock were withheld to cover his tax liabilities from RSU vesting, leaving him with 177,036 shares of Common Stock held directly.

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

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^*

PETERS WILLIAM J

(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		10% Owner
X	Officer (give title below)		Other (specify below)
	CFO, EVP & TREASURER

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)

X	Form filed by One Reporting Person
	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		58,693(1)	A	$0	180,333	D
Common Stock	03/10/2026		F		3,297(2)	D	$18.91	177,036	D

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		121,071		(3)	03/09/2036	Common Stock	121,071	$0	121,071	D

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

	/s/ William J. Peters	03/11/2026
	** 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.

FAQ

What equity awards did Amphastar (AMPH) CFO William J. Peters receive?

William J. Peters received a grant of 58,693 restricted stock units (RSUs) and an employee stock option over 121,071 shares of Common Stock at $19.21 per share. Both awards vest in four equal annual installments starting March 9, 2027.

How many Amphastar (AMPH) shares does the CFO hold after these Form 4 transactions?

After the reported transactions, William J. Peters directly holds 177,036 shares of Amphastar Common Stock. This figure reflects his position following the 3,297-share tax-withholding disposition related to RSU vesting disclosed in the Form 4.

What are the vesting terms of the CFO’s new RSUs at Amphastar (AMPH)?

The reported RSUs representing 58,693 shares of Amphastar Common Stock vest in four equal annual installments, beginning on March 9, 2027. Each year, one-quarter of the RSUs is scheduled to vest if applicable service conditions are met.

What are the key terms of the CFO’s new stock option grant at Amphastar (AMPH)?

The employee stock option covers 121,071 shares of Common Stock at an exercise price of $19.21 per share and expires in 2036. The option vests in four equal annual installments starting on March 9, 2027, aligning with typical long-term incentives.

Was there any open-market buying or selling by the Amphastar (AMPH) CFO in this Form 4?

No open-market purchases or sales are reported. The Form 4 shows equity grants (RSUs and options) and a 3,297-share tax-withholding disposition to cover RSU-related taxes, which is a mechanical process rather than a discretionary market trade.

Why were 3,297 Amphastar (AMPH) shares disposed of in the CFO’s Form 4?

The 3,297 shares of Common Stock were withheld to satisfy William J. Peters’ tax liability in connection with the vesting of RSUs. This tax-withholding disposition is recorded with transaction code F, indicating payment of taxes by delivering shares.