Amphastar (AMPH) EVP Yakob reports RSU tax withholding, holds over 89K shares

Rhea-AI Filing Summary

Amphastar Pharmaceuticals EVP Liawatidewi Yakob reported a routine tax-related share disposition. On March 6, 2026, 1,144 shares of common stock were withheld at $19.34 per share to cover taxes on vesting restricted stock units, not as an open-market sale.

After this withholding, Yakob directly holds 89,345 shares of Amphastar common stock and indirectly holds 2,459 shares through the Yakob and Sunmoon Trust dated July 25, 2013, where she serves as trustee.

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)
03/06/2026

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	03/06/2026		F		1,144(1)	D	$19.34	89,345	D
Common Stock								2,459	I	See footnote(2)

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. 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/ Eva Wen, by power of attorney	03/10/2026
	** 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) EVP Liawatidewi Yakob report in this Form 4?

EVP Liawatidewi Yakob reported a routine tax-withholding disposition involving 1,144 Amphastar common shares. The shares were withheld to satisfy her tax liability from vesting restricted stock units, rather than being sold in the open market, and her overall ownership remains substantial.

How many Amphastar (AMPH) shares were withheld for Liawatidewi Yakob’s taxes?

A total of 1,144 Amphastar common shares were withheld at $19.34 per share. This withholding satisfied her tax obligation related to vesting restricted stock units, a common administrative step when equity awards convert into shares for executives.

How many Amphastar (AMPH) shares does Liawatidewi Yakob hold after this filing?

Following the tax withholding, Liawatidewi Yakob directly holds 89,345 Amphastar common shares. She also indirectly holds 2,459 additional shares through the Yakob and Sunmoon Trust dated July 25, 2013, where she serves as trustee with record ownership.

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

No, the Form 4 shows a tax-withholding disposition, not an open-market sale. The 1,144 shares were withheld by the issuer to cover her tax liability from vesting restricted stock units, a standard mechanism that does not reflect discretionary selling activity.

What is the Yakob and Sunmoon Trust mentioned in the Amphastar (AMPH) Form 4?

The Yakob and Sunmoon Trust dated July 25, 2013 holds 2,459 Amphastar shares of record. Liawatidewi Yakob serves as a trustee of this trust, and these indirect holdings are reported separately from her directly owned Amphastar common stock.

Does this Amphastar (AMPH) Form 4 indicate a major change in insider ownership?

The filing reflects a small tax-withholding event of 1,144 shares alongside substantial remaining holdings. With 89,345 direct shares and 2,459 indirect trust shares reported, the transaction appears administrative rather than a large, discretionary change in insider ownership.