Amphastar director granted RSUs and stock options

Amphastar Pharmaceuticals director Diane G. Gerst received equity compensation consisting of 8,143 shares of common stock in the form of restricted stock units and a stock option for 17,365 shares at an exercise price of $18.42 per share.

Rhea-AI Filing Summary

Amphastar Pharmaceuticals director Diane G. Gerst received equity compensation consisting of 8,143 shares of common stock in the form of restricted stock units and a stock option for 17,365 shares at an exercise price of $18.42 per share. All RSUs and option shares vest on June 1, 2027. Following these awards, she directly holds 31,899 shares of common stock.

Insider Trade Summary

Grant/Award: 25,508 shares

Grant/Award 2 txns

Insider Gerst Diane G.

Role Director

Type	Security	Shares	Price	Value
Grant/Award	Stock Option (right to buy)	17,365	$0.00	$0.00
Grant/Award	Common Stock	8,143	$0.00	$0.00

Holdings After Transaction: Stock Option (right to buy) — 17,365 contracts (Direct); Common Stock — 31,899 shares (Direct)

Footnotes (2)

1. F1. The reported shares are represented by restricted stock units, or RSUs, all of which vest on June 1, 2027.
2. F2. All of the shares subject to the option vest on June 1, 2027.

Key Figures

RSU grant: 8,143 shares Stock option size: 17,365 shares Option exercise price: $18.42 per share +3 more

6 metrics

RSU grant 8,143 shares Restricted stock units vesting on June 1, 2027

Stock option size 17,365 shares Option covering Amphastar common stock granted June 1, 2026

Option exercise price $18.42 per share Exercise price for 17,365-share stock option

Option expiration June 1, 2036 Expiration date of director stock option

Post-award holdings 31,899 shares Common stock directly owned after June 1, 2026 grants

Award vesting date June 1, 2027 Vesting date for all RSUs and option shares granted

Key Terms

restricted stock units, stock option, vest

3 terms

restricted stock units financial

"The reported shares are represented by restricted stock units, or RSUs, all of which vest on June 1, 2027."

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

stock option financial

"Stock Option (right to buy) with 17,365 shares at an exercise price of $18.42 per share."

A stock option is a contract that gives you the right to buy or sell a company's stock at a specific price within a certain time frame. People use them to potentially make money if the stock's price moves favorably or to protect against losses. It's like holding a coupon that can be used to buy or sell stock at a set price later on.

vest financial

"All of the shares subject to the option vest on June 1, 2027."

A vest is the process by which an employee earns the right to receive certain benefits or ownership interests, such as stock or retirement funds, over time. It’s similar to earning a reward gradually, ensuring that the benefit becomes fully yours only after a set period or meeting specific conditions. This makes it important for investors because it determines when they can actually claim or use those benefits.

FAQ

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

What insider transactions did AMPH director Diane G. Gerst report?

Diane G. Gerst reported receiving equity awards, not open-market trades. She was granted 8,143 restricted stock units and a stock option for 17,365 shares of Amphastar common stock as part of her director compensation.

How many Amphastar (AMPH) shares were granted to Diane G. Gerst?

She received 8,143 restricted stock units representing common shares and a stock option covering 17,365 additional common shares. These awards increase her potential ownership if the options are later exercised after vesting.

What is the exercise price and term of Diane G. Gerst’s AMPH stock option?

Her stock option covers 17,365 shares at an exercise price of $18.42 per share. The option expires on June 1, 2036, giving her a long-dated right to purchase Amphastar common stock after vesting.

When do Diane G. Gerst’s AMPH restricted stock units and options vest?

All of Diane G. Gerst’s newly granted equity awards vest on June 1, 2027. This includes both the 8,143 restricted stock units and all 17,365 shares subject to the stock option granted on the same date.

How many Amphastar (AMPH) shares does Diane G. Gerst own after these grants?

After these awards, Diane G. Gerst directly holds 31,899 shares of Amphastar common stock. This figure reflects her reported direct ownership immediately following the June 1, 2026 equity grants.

Were Diane G. Gerst’s AMPH transactions open-market buys or sales?

No, the reported transactions are classified as grants or awards, not market trades. She acquired restricted stock units and stock options as compensation rather than buying or selling shares on the open market.

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

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Accepted by SEC EDGAR 06/03/2026 - 08:33 PM EDT 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^*

Gerst Diane G.

(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
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
06/01/2026

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	06/01/2026		A		8,143(1)	A	$0	31,899	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
Stock Option (right to buy)	$18.42	06/01/2026		A		17,365		(2)	06/01/2036	Common Stock	17,365	$0	17,365	D

Explanation of Responses:

1. The reported shares are represented by restricted stock units, or RSUs, all of which vest on June 1, 2027.

2. All of the shares subject to the option vest on June 1, 2027.

	/s/ Eva Wen, by power of attorney	06/03/2026
	** 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)