Amphastar director disposes 500 shares; 76,531 remain owned

Rhea-AI Filing Summary

Floyd F. Petersen, a director of Amphastar Pharmaceuticals (AMPH), sold 500 shares on 09/02/2025 under a pre-existing Rule 10b5-1 trading plan. The sales were executed at a weighted-average price of $30.9833 per share, with individual sale prices ranging from $30.60 to $31.225. Following the reported disposition, Petersen is recorded as beneficially owning 76,531 shares. The Form 4 was signed by Eva Wen by power of attorney on 09/03/2025.

Insights

Securities Analyst

TL;DR: Routine insider sale under a 10b5-1 plan; small absolute size relative to typical director holdings.

The transaction shows a director-initiated sale of 500 shares executed pursuant to a Rule 10b5-1 plan adopted on November 26, 2024. The disclosure includes the weighted-average sale price and the remaining beneficial ownership of 76,531 shares. This filing appears procedural and consistent with planned trading activity rather than an opportunistic or ad hoc trade. No derivative transactions or other unusual instruments are reported.

Corporate Governance Expert

TL;DR: Governance controls appear in place via a documented 10b5-1 plan; disclosure meets Section 16 requirements.

The report identifies the 10b5-1 plan adoption date and discloses the weighted-average price range, enabling transparency about execution. The Form 4 is signed by a power of attorney, which is common for administrative filings. There are no indications of change in director status or other governance events in this filing.

Insider Trade Summary

Net Seller: 500 shares ($15,492)

Net Sell 1 txn

Insider Petersen Floyd F.

Role Director

Sold 500 shs ($15K)

Type	Security	Shares	Price	Value
Sale	Common Stock	500	$30.9833	$15K

Holdings After Transaction: Common Stock — 76,531 shares (Direct)

Footnotes (1)

1. The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 26, 2024. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.60 to $31.225, 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.

Form 4 Insider Transactions: What Each Field Means →

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).

X

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)
09/02/2025

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	09/02/2025		S(1)		500	D	$30.9833(2)	76,531	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

Explanation of Responses:

1. The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 26, 2024.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.60 to $31.225, 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	09/03/2025
	** 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 Floyd F. Petersen report on Form 4 for AMPH?

The Form 4 reports that Floyd F. Petersen sold 500 shares of Amphastar on 09/02/2025 pursuant to a 10b5-1 plan.

At what price were the AMPH shares sold in the Form 4?

The shares were sold at a weighted-average price of $30.9833, with individual sale prices ranging from $30.60 to $31.225.

How many AMPH shares does Petersen beneficially own after the reported sale?

Following the reported transaction, Petersen beneficially owns 76,531 shares.

Was the sale reported on Form 4 part of a Rule 10b5-1 plan?

Yes. The sale was effected pursuant to a Rule 10b5-1 trading plan adopted on November 26, 2024.

Who signed the Form 4 for the reporting person?

The Form 4 was signed by Eva Wen by power of attorney on 09/03/2025.