Amphastar (AMPH) EVP Yakob has 965 shares withheld for RSU taxes

Rhea-AI Filing Summary

Amphastar Pharmaceuticals director and EVP Liawatidewi Yakob reported a tax-related share disposition. On March 4, 2026, 965 shares of common stock were withheld at $19.96 per share to satisfy her tax liability upon vesting of restricted stock units.

After this tax-withholding disposition, she directly held 90,489 common shares. She also indirectly held 2,459 shares through the Yakob and Sunmoon Trust dated July 25, 2013, which includes 545 shares acquired on May 31, 2025 under Amphastar’s 2014 Employee Stock Purchase Plan.

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^*

Liawatidewi Yakob

(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)
	EVP CORP ADMIN CENTER

3. Date of Earliest Transaction (Month/Day/Year)
03/04/2026

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	03/04/2026		F		965(1)	D	$19.96	90,489(2)	D
Common Stock								2,459	I	See footnote(3)

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

Explanation of Responses:

1. The reported shares were withheld to satisfy the reporting person's tax liability in connection with the vesting of restricted stock units, or RSUs.

2. Includes 545 shares acquired on May 31, 2025 under the Issuer's 2014 Employee Stock Purchase Plan.

3. The reported shares are held of record by the Yakob and Sunmoon Trust dated July 25, 2013 for which the reporting person serves as a trustee.

	/s/ Yakob Liawatidewi	03/06/2026
	** 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).
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FAQ

What did Amphastar (AMPH) executive Liawatidewi Yakob report in this Form 4?

She reported a tax-withholding disposition of Amphastar common stock. On March 4, 2026, 965 shares were withheld to cover taxes from restricted stock unit vesting, rather than sold in an open-market transaction, and her updated direct and indirect holdings were disclosed.

How many Amphastar (AMPH) shares were disposed of in Yakob’s March 4, 2026 transaction?

A total of 965 Amphastar common shares were disposed of. These shares were withheld at $19.96 per share to satisfy Liawatidewi Yakob’s tax liability related to vesting restricted stock units, according to the Form 4 and its accompanying explanatory footnote.

Was Liawatidewi Yakob’s Amphastar (AMPH) Form 4 transaction an open-market sale?

No, the Form 4 describes a tax-withholding disposition, not an open-market sale. Shares were withheld by Amphastar to pay taxes triggered by restricted stock unit vesting, as indicated by transaction code F and the related footnote explanation.

What are Liawatidewi Yakob’s direct Amphastar (AMPH) share holdings after this Form 4?

Following the tax-withholding disposition, she directly held 90,489 shares of Amphastar common stock. This updated post-transaction balance reflects the 965 shares withheld on March 4, 2026 to satisfy her associated tax obligation from restricted stock unit vesting.

What indirect Amphastar (AMPH) share holdings are reported for Yakob?

She indirectly held 2,459 Amphastar common shares. These shares are recorded under the Yakob and Sunmoon Trust dated July 25, 2013, where she serves as trustee, and include 545 shares acquired on May 31, 2025 through the 2014 Employee Stock Purchase Plan.

What does transaction code F mean in this Amphastar (AMPH) Form 4?

Transaction code F indicates shares were used to pay an exercise price or tax liability. Here, 965 Amphastar shares were withheld on March 4, 2026 to satisfy Liawatidewi Yakob’s tax obligation upon restricted stock unit vesting, rather than through a discretionary market sale.