Sell4

Amphastar Pharmaceuticals, Inc.

AMPH

Total Value

$506.4K

Net $239.4K sold

Filing Date

Sep 17, 2026

1 transaction

Sales

$239.4K

1 transaction

Trade Summary

On Sep 16, 2026, Zhou Rong, Insider, sold $506.4K of Amphastar Pharmaceuticals, Inc. (AMPH) across 1 transaction. The filing covers Common Stock and reflects net selling of $239.4K. Reported prices ranged from $13.35 to $23.94. Insider transactions are sourced from SEC Form 4 disclosures and should be reviewed alongside company fundamentals and the insider's broader trading history.

Price at the Time of the Trade

AMPH daily price with the insider's sale marked at $23.94.

Sold near the 6-month high · about level with today's price.

Price data is delayed and provided for context only — not investment advice.

Insider Information

Name: Zhou Rong
Role: Insider
Location: RANCHO CUCAMONGA, CA

Filing Details

Filing Date: Sep 17, 2026
Transaction Date: Sep 16, 2026
Accession Number: 0001645326-26-000014
Form Type: 4
Net Trading Amount: -$239.4K

Non-Derivative Transactions

Date	Security	Shares	Price	Type	Value
Sep 16, 2026	Common Stock	10,000	$13.35	Exercise	$133.5K
Sep 16, 2026	Common Stock	10,000	$23.94	Sale	$239.4K

Derivative Transactions

Date	Security	Shares	Exercise Price	Type	Value
Sep 16, 2026	AMPH derivative	10,000	$13.35	Exercise	$133.5K

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Footnotes

(F1)The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $23.83 to $24.05, 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.
(F2)The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee.
(F3)The shares are held of record by the reporting person's spouse.
(F4)Shares subject to the option are fully vested and immediately exercisable.

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^*

Zhou Rong

(Last)

(First)

(Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC.

11570 6TH STREET

(Street)

RANCHO CUCAMONGA

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)

	Director	10% Owner
X	Officer (give title below)	Other (specify below)
	SENIOR EVP, PRODUCTION CENTER

3. Date of Earliest Transaction (Month/Day/Year)
09/16/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	09/16/2026		M		10,000	A	$13.35	179,203	D
Common Stock	09/16/2026		S		10,000	D	$23.9404⁽¹⁾	169,203	D
Common Stock								99,668	I	See footnote⁽²⁾
Common Stock								5,000	I	See footnote⁽³⁾

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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Employee Stock Option (right to buy)	$13.35	09/16/2026		M			10,000	⁽⁴⁾	03/16/2027	Common Stock	10,000	$0	19,424	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 $23.83 to $24.05, 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. The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee.

3. The shares are held of record by the reporting person's spouse.

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

	/s/ Eva Wen, by power of attorney	09/17/2026
	** 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.

Form 4 as rendered by the SEC from accession 0001645326-26-000014.

Amphastar Pharmaceuticals, Inc.

Trade Summary

Price at the Time of the Trade

Company Information

Insider Information

Filing Details

Non-Derivative Transactions

Derivative Transactions

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Footnotes

SEC Form 4

SEC Filing

SEC Form 4

Price at the Time of the Trade