[Form 4] Amphastar Pharmaceuticals, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Amphastar Pharmaceuticals, Inc. (AMPH)16,679 shares of common stock at an exercise price of $16.69 per share and acquired those shares. On the same date, the director sold 16,679 shares of common stock at a weighted average price of $26.4906 per share, with individual sale prices ranging from $26.43 to $26.57. After these transactions, the director beneficially owned 75,531 shares of Amphastar common stock directly. The stock option covering 16,679 shares, which was fully vested and immediately exercisable and had an expiration date of 06/07/2026, now shows 0 derivative securities remaining beneficially owned.

11/17/2025 - 04:16 PM

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^*

Petersen Floyd F.

(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
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
11/13/2025

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	11/13/2025		M		16,679	A	$16.69	92,210	D
Common Stock	11/13/2025		S		16,679	D	$26.4906(1)	75,531	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
Stock Option (right to buy)	$16.69	11/13/2025		M			16,679	(2)	06/07/2026	Common Stock	16,679	$0	0	D

Explanation of Responses:

1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $26.43 to $26.57, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price.

2. Shares subject to the option are fully vested and immediately exercisable.

	/s/ Eva Wen, by power of attorney	11/17/2025
	** 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 insider transaction did Amphastar (AMPH) report in this Form 4?

The filing reports that a director of Amphastar Pharmaceuticals, Inc. (AMPH) exercised a stock option for 16,679 shares of common stock at $16.69 per share and sold 16,679 shares of common stock on 11/13/2025.

At what prices were Amphastar (AMPH) shares sold by the director?

The director sold 16,679 shares of Amphastar common stock at a weighted average price of $26.4906 per share, with individual sale prices ranging from $26.43 to $26.57 on 11/13/2025.

How many Amphastar (AMPH) shares does the director own after the transaction?

Following the reported transactions, the director beneficially owned 75,531 shares of Amphastar common stock directly.

What happened to the Amphastar (AMPH) stock option reported in Table II?

The director exercised a stock option (right to buy) covering 16,679 shares of Amphastar common stock at an exercise price of $16.69 per share. After the exercise, the number of derivative securities beneficially owned from this option was reported as 0.

Were the Amphastar (AMPH) option shares fully vested at the time of exercise?

Yes. The filing states that the shares subject to the option were fully vested and immediately exercisable at the time of the transaction.

What was the expiration date of the exercised Amphastar (AMPH) stock option?

The exercised stock option for 16,679 shares of Amphastar common stock had an expiration date of 06/07/2026 before it was exercised in full.

How is the sale price of Amphastar (AMPH) shares described in the Form 4?

The sale price is reported as a weighted average price of $26.4906 per share, with sales occurring in multiple transactions between $26.43 and $26.57 per share.