Amphastar CFO trades stock under 10b5-1 plan

Amphastar Pharmaceuticals, Inc. director and CFO/EVP/Treasurer William J. Peters reported an options exercise and share sale.

Rhea-AI Filing Summary

Amphastar Pharmaceuticals, Inc. director and CFO/EVP/Treasurer William J. Peters reported an options exercise and share sale. On August 7, 2026, he exercised 5,053 Employee Stock Options at an exercise price of $19.79 per share, receiving 5,053 shares of common stock and closing out that option grant. The same day, he sold 8,180 shares of common stock at $22.48 per share in a transaction described as a sale in the open market or a private transaction. The sale was executed pursuant to a Rule 10b5-1 trading plan adopted on March 10, 2026. A related holding footnote states that reported common stock holdings include 910 shares acquired on May 31, 2026 under the company’s 2014 Employee Stock Purchase Plan.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 3 txns

Insider PETERS WILLIAM J

Role CFO, EVP & TREASURER

Sold 8,180 shs ($184K)

Approx. gross sale proceeds $184K

Approx. exercise cost $100K

Type	Security	Shares	Price	Value
Exercise	Employee Stock Option (right to buy) F3	5,053	$0.00	$0.00
Exercise	Common Stock F1	5,053	$19.79	$100K
Sale	Common Stock F2	8,180	$22.48	$184K

Holdings After Transaction: Employee Stock Option (right to buy) — 0 contracts (Direct); Common Stock — 172,846 shares (Direct)

Footnotes (3)

1. F1. Includes 910 shares acquired on May 31, 2026 under the Issuer's 2014 Employee Stock Purchase Plan.
2. F2. The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 10, 2026.
3. F3. Shares subject to the option are fully vested and immediately exercisable.

Key Figures

Options Exercised: 5,053 shares Option Exercise Price: $19.79 per share Shares Sold: 8,180 shares +4 more

7 metrics

Options Exercised 5,053 shares Employee Stock Option exercised on August 7, 2026

Option Exercise Price $19.79 per share Exercise price for 5,053 Employee Stock Options

Shares Sold 8,180 shares Common stock sale on August 7, 2026

Sale Price $22.48 per share Price for 8,180 common shares sold

Options Remaining in This Grant 0 shares Shares subject to the reported option following exercise

ESPP Shares Included 910 shares Common shares acquired May 31, 2026 under 2014 Employee Stock Purchase Plan

Net Buy/Sell Shares -8,180 shares Transaction summary net-sell direction across reported trades

Key Terms

Employee Stock Option, Rule 10b5-1 trading plan, Employee Stock Purchase Plan, Exercise or conversion of derivative security, +1 more

5 terms

Employee Stock Option financial

"Employee Stock Option (right to buy)"

An employee stock option is a promise that lets a worker buy company shares later at a predetermined price, often after they stay for a certain period or meet performance goals — think of it like a coupon that locks in today's price for a future purchase. It matters to investors because options align employees’ incentives with company performance, can increase the number of shares outstanding (dilution) when exercised, and represent a compensation cost that affects reported profits and shareholder value.

Rule 10b5-1 trading plan regulatory

"sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

Employee Stock Purchase Plan financial

"Includes 910 shares acquired on May 31, 2026 under the Issuer's 2014 Employee Stock Purchase Plan."

An employee stock purchase plan is a company program that lets workers buy shares through small payroll deductions, often at a discount to the market price and after a set offering period. Think of it like a workplace savings plan that turns into ownership: it encourages employees to share in the company’s success and can create predictable buying or selling of stock that investors watch because it affects supply, demand and employee incentives.

Exercise or conversion of derivative security financial

"transaction_code_description":"Exercise or conversion of derivative security"

Sale in open market or private transaction financial

"transaction_code_description":"Sale in open market or private transaction"

FAQ

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

What did Amphastar (AMPH) CFO William J. Peters report in this Form 4?

He reported exercising 5,053 stock options at $19.79 per share and selling 8,180 common shares at $22.48 per share on August 7, 2026.

How many Amphastar (AMPH) shares did the CFO sell and at what price?

William J. Peters sold 8,180 shares of common stock at a price of $22.48 per share on August 7, 2026, in an open-market or private transaction.

Were the Amphastar (AMPH) insider sales under a Rule 10b5-1 plan?

Yes. The filing notes the August 7, 2026 sale of 8,180 shares was made pursuant to a Rule 10b5-1 trading plan adopted on March 10, 2026.

What options did the Amphastar (AMPH) CFO exercise in this Form 4?

He exercised an Employee Stock Option for 5,053 shares of common stock at an exercise price of $19.79 per share; the option was fully vested and immediately exercisable.

Does the Form 4 mention Amphastar (AMPH) shares from an Employee Stock Purchase Plan?

Yes. A holding footnote states reported common stock holdings include 910 shares acquired on May 31, 2026 under Amphastar’s 2014 Employee Stock Purchase Plan.

What is the net share effect of the Amphastar (AMPH) CFO’s reported transactions?

Across the reported transactions, the Form 4 summary shows a net-sell of 8,180 shares, reflecting one options exercise and one sale of common stock.

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

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Available on EDGAR 08/11/2026 - 04:57 PM Accepted by SEC EDGAR 08/11/2026 - 04:57 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).

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^*

PETERS WILLIAM J

(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)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	CFO, EVP & TREASURER

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/07/2026

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	08/07/2026		M		5,053	A	$19.79	181,026(1)	D
Common Stock	08/07/2026		S(2)		8,180	D	$22.48	172,846	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
Employee Stock Option (right to buy)	$19.79	08/07/2026		M			5,053	(3)	03/15/2028	Common Stock	5,053	$0	0	D

Explanation of Responses:

1. Includes 910 shares acquired on May 31, 2026 under the Issuer's 2014 Employee Stock Purchase Plan.

2. The sale reported in this Form 4 was effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on March 10, 2026.

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

	/s/ William J. Peters	08/11/2026
	** 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)