Amphastar EVP has shares withheld for RSU taxes

Amphastar Pharmaceuticals director and EVP Liawatidewi Yakob reported a tax-withholding share disposition related to RSU vesting.

Rhea-AI Filing Summary

Amphastar Pharmaceuticals director and EVP Liawatidewi Yakob reported a tax-withholding share disposition related to RSU vesting. On 2026-03-15, 1,033 shares of Common Stock were withheld at $18.18 per share to cover her tax liability from vested restricted stock units.

After this non-market tax-withholding event, she directly holds 121,892 shares of Amphastar Common Stock. An additional 2,459 shares are held indirectly by the Yakob and Sunmoon Trust dated July 25, 2013, for which she serves as a trustee.

Insider Trade Summary

Exercise Price or Tax Liability: 1,033 shares

Exercise Price or Tax Liability 2 txns

Insider Liawatidewi Yakob

Role EVP CORP ADMIN CENTER

Type	Security	Shares	Price	Value
Exercise Price or Tax Liability	Common Stock	1,033	$18.18	$19K
holding	Common Stock	--	--	--

Holdings After Transaction: Common Stock — 121,892 shares (Direct); Common Stock — 2,459 shares (Indirect, See footnote)

Footnotes (2)

1. F1. 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. F2. 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

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

She reported 1,033 Amphastar shares withheld to cover taxes from RSU vesting. This tax-withholding disposition is coded “F” and is not an open-market sale, but a routine mechanism to satisfy personal tax obligations on equity compensation.

How many Amphastar (AMPH) shares were withheld for taxes in the filing?

The filing shows 1,033 shares of Amphastar Common Stock withheld at a price of $18.18 per share. These shares covered Liawatidewi Yakob’s tax liability arising from the vesting of restricted stock units granted as part of her compensation.

Does the Form 4 indicate an open-market sale of AMPH shares by the EVP?

No, the Form 4 reports a tax-withholding disposition, not an open-market sale. Shares were withheld by the company to pay taxes on vested RSUs, which is a standard administrative transaction rather than a discretionary buy or sell decision.

What are Liawatidewi Yakob’s Amphastar (AMPH) direct holdings after this transaction?

Following the tax-withholding event, she directly holds 121,892 shares of Amphastar Common Stock. This figure reflects her remaining direct ownership position after the 1,033 shares were withheld to satisfy tax obligations related to restricted stock unit vesting.

What indirect Amphastar (AMPH) holdings are disclosed for Liawatidewi Yakob?

The Form 4 shows 2,459 shares held indirectly by the Yakob and Sunmoon Trust dated July 25, 2013. Liawatidewi Yakob serves as a trustee of this trust, which is listed as holding these additional Amphastar Common Stock shares of record.

How does the filing classify the tax-related AMPH share disposition?

The disposition is classified with transaction code “F,” described as payment of tax liability by delivering securities. It is also labeled as a tax-withholding disposition, emphasizing that shares were used to cover taxes on RSU vesting, not sold on the open market.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 03/17/2026 - 08:17 PM EDT Learn about SEC filing dates

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^*

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)
03/15/2026

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	03/15/2026		F		1,033(1)	D	$18.18	121,892	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	03/17/2026
	** 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.