Amphastar EVP sells 3,187 shares at $23.63

Senior EVP at Amphastar Pharmaceuticals reported a modest open-market share sale while retaining a substantial direct and indirect equity position.

Rhea-AI Filing Summary

Amphastar Pharmaceuticals, Inc. (AMPH) executive Rong Zhou, Senior EVP, Production Center, reported selling 3,187 shares of common stock on September 2, 2026 in an open-market or private transaction at a weighted average price of $23.6291 per share, with trade prices ranging from $23.62 to $23.69.

After this sale, Zhou directly holds 169,203 shares of Amphastar common stock, including 836 shares acquired on May 31, 2026 under the company’s 2014 Employee Stock Purchase Plan. Additional indirect holdings are reported through the Zhou Family Trust and the reporting person’s spouse. No Rule 10b5-1 trading plan is reported.

Insider Trade Summary

Net Seller: 3,187 shares

Net Sell 3 txns

Insider Zhou Rong

Role SENIOR EVP, PRODUCTION CENTER

Sold 3,187 shs ($75K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	3,187	$23.6291	$75K
holding	Common Stock F3	--	--	--
holding	Common Stock F4	--	--	--

Holdings After Transaction: Common Stock — 169,203 shares (Direct); Common Stock — 104,668 shares (Indirect, See footnote)

Footnotes (4)

1. F1. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $23.62 to $23.69, 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. F2. Includes 836 shares acquired on May 31, 2026 under the Issuer's 2014 Employee Stock Purchase Plan.
3. F3. The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee.
4. F4. The shares are held of record by the reporting person's spouse.

Key Figures

Shares sold: 3,187 shares Weighted average sale price: $23.6291 per share Direct holdings after transaction: 169,203 shares +2 more

5 metrics

Shares sold 3,187 shares Common stock sale reported for September 2, 2026

Weighted average sale price $23.6291 per share Sale of 3,187 shares with prices from $23.62 to $23.69

Direct holdings after transaction 169,203 shares Direct Amphastar common stock held by Rong Zhou after the sale

ESPP shares included in holdings 836 shares Shares acquired on May 31, 2026 under 2014 Employee Stock Purchase Plan

Net buy/sell direction 3,187 shares net sold Transaction summary for this Form 4

Key Terms

weighted average price, 2014 Employee Stock Purchase Plan, indirect ownership

3 terms

weighted average price financial

"The price reported in Column 4 is a weighted average price."

Weighted average price is the average price of a security where each trade or component is counted according to its size, so bigger trades pull the average more than smaller ones. Think of it like calculating the average cost of a grocery haul where items you bought more of have greater influence on the final per-item cost. Investors use it to understand the true average price paid or received, judge execution quality, and compare trading performance against market movement.

2014 Employee Stock Purchase Plan financial

"Includes 836 shares acquired on May 31, 2026 under the Issuer's 2014 Employee Stock Purchase Plan."

indirect ownership financial

"The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee."

FAQ

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

What insider transaction did AMPH executive Rong Zhou report on this Form 4?

Rong Zhou reported a sale of 3,187 shares of Amphastar Pharmaceuticals common stock on September 2, 2026 in an open-market or private transaction at a weighted average price of $23.6291 per share, with prices ranging from $23.62 to $23.69.

How many AMPH shares does Rong Zhou hold after the reported sale?

After the sale, Rong Zhou directly holds 169,203 shares of Amphastar Pharmaceuticals common stock. This direct position includes 836 shares acquired on May 31, 2026 under Amphastar’s 2014 Employee Stock Purchase Plan, in addition to indirect holdings through a family trust and spouse.

At what price were the AMPH shares sold by Rong Zhou?

The reported sale was executed at a weighted average price of $23.6291 per share. The individual transaction prices ranged from $23.62 to $23.69, and the reporting person has undertaken to provide full trade-break information upon request to specified parties.

Were Rong Zhou’s AMPH share sales under a Rule 10b5-1 trading plan?

No. The filing indicates that the Rule 10b5-1 checkbox is not affirmed, and the footnotes do not describe any Rule 10b5-1 or similar pre-arranged trading plan for this 3,187-share sale of Amphastar Pharmaceuticals stock.

What indirect AMPH shareholdings are reported for Rong Zhou?

The filing notes that some Amphastar shares are held indirectly: one block is held of record by the Zhou Family Trust, where Rong Zhou serves as a trustee, and another block is held of record by the reporting person’s spouse.

What role does Rong Zhou hold at Amphastar Pharmaceuticals (AMPH)?

Rong Zhou is reported as an officer of Amphastar Pharmaceuticals, serving as Senior EVP, Production Center. The Form 4 reflects transactions and holdings in the company’s common stock associated with this reporting person.

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

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Available on EDGAR 09/03/2026 - 07:42 PM Accepted by SEC EDGAR 09/03/2026 - 07:42 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^*

Zhou Rong

(Last) (First) (Middle)

C/O AMPHASTAR PHARMACEUTICALS, INC.

11570 6TH STREET

(Street)

RANCHO CUCAMONGA CALIFORNIA 91730

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
09/02/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

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	09/02/2026		S		3,187	D	$23.6291(1)	169,203(2)	D
Common Stock								99,668	I	See footnote(3)
Common Stock								5,000	I	See footnote(4)

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 $23.62 to $23.69, 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. Includes 836 shares acquired on May 31, 2026 under the Issuer's 2014 Employee Stock Purchase Plan.

3. The shares are held of record by the Zhou Family Trust for which the reporting person serves as a trustee.

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

	/s/ Eva Wen, by power of attorney	09/03/2026
	** 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: SEC 1474 (03-26)