Amphastar director reports stock sales on December 11 and 12

Rhea-AI Filing Summary

Amphastar Pharmaceuticals reported that one of its directors sold Amphastar common stock in two open-market transactions. On December 11, 2025, the director sold 1,737 shares at $25.688 per share. On December 12, 2025, the director sold 2,426 shares at a weighted average price of $25.9226 per share, with individual trades ranging from $25.9225 to $25.945.

After these sales, the director beneficially owned 71,368 shares of Amphastar common stock, held directly. The report states that full detail on the number of shares sold at each separate price is available upon request from the issuer, any security holder, or the SEC staff.

Insider Trade Summary

Net Seller: 4,163 shares

Net Sell 2 txns

Insider Petersen Floyd F.

Role Director

Sold 4,163 shs ($108K)

Type	Security	Shares	Price	Value
Sale	Common Stock	2,426	$25.9226	$63K
Sale	Common Stock	1,737	$25.688	$45K

Holdings After Transaction: Common Stock — 71,368 shares (Direct)

Footnotes (1)

1. F1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $25.9225 to $25.945, 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.

FAQ

What insider transaction did Amphastar Pharmaceuticals (AMPH) report in this Form 4?

A director of Amphastar Pharmaceuticals reported selling Amphastar common stock in two transactions on December 11 and 12, 2025.

How many Amphastar (AMPH) shares did the director sell and on which dates?

The director sold 1,737 shares on December 11, 2025 and 2,426 shares on December 12, 2025.

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

Shares were sold at $25.688 per share on December 11, 2025 and at a weighted average price of $25.9226 per share on December 12, 2025, with trades from $25.9225 to $25.945.

How many Amphastar Pharmaceuticals (AMPH) shares does the director own after these sales?

Following the reported transactions, the director beneficially owned 71,368 shares of Amphastar common stock, held directly.

What is the reporting person’s relationship to Amphastar Pharmaceuticals (AMPH)?

The reporting person is identified as a director of Amphastar Pharmaceuticals.

Was this Amphastar (AMPH) Form 4 filed for one or multiple reporting persons?

The Form 4 indicates it was filed by one reporting person.

Does the filing explain how the weighted average sale price for Amphastar (AMPH) shares was calculated?

Yes. It states the weighted average price reflects multiple transactions between $25.9225 and $25.945, and detailed trade data is available upon request.

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Accepted by SEC EDGAR 12/15/2025 - 05:17 PM 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^*

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)
12/11/2025

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	12/11/2025		S		1,737	D	$25.688	73,794	D
Common Stock	12/12/2025		S		2,426	D	$25.9226(1)	71,368	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

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 $25.9225 to $25.945, 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.

	/s/ Eva Wen, by power of attorney	12/15/2025
	** 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.