Amphastar CFO Peters sells 16,000 shares at $28.03

Both reported sales were made under a Rule 10b5-1 trading plan adopted March 10, 2026.

Available on EDGAR 11/06/2026 - 04:17 PM EST Accepted by SEC EDGAR 11/06/2026 - 04:17 PM EST

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Rhea-AI Filing Summary

Amphastar Pharmaceuticals, Inc. CFO, EVP & Treasurer William J. Peters exercised options covering 16,000 shares on November 4, 2026, at an exercise price of $13.03 per share, and 11,000 shares on November 5 at $17.99 per share. He sold 16,000 shares at $28.03 per share on November 4 and 12,631 shares at a weighted average price of $28.9913 per share on November 5. Both sales were made under a Rule 10b5-1 trading plan adopted March 10, 2026. The November 5 sale involved multiple transactions at prices from $28.99 to $29.00, inclusive.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 6 txns

Insider PETERS WILLIAM J

Role CFO, EVP & TREASURER

Sold 28,631 shs ($815K)

Approx. gross sale proceeds $815K

Approx. exercise cost $406K

Type	Security	Shares	Price	Value
Exercise	Employee Stock Option (right to buy) ^F3	11,000	$0.00	$0.00
Exercise	Common Stock	11,000	$17.99	$198K
Sale	Common Stock ^{F1, F2}	12,631	$28.9913	$366K
Exercise	Employee Stock Option (right to buy) ^F3	16,000	$0.00	$0.00
Exercise	Common Stock	16,000	$13.03	$208K
Sale	Common Stock ^F1	16,000	$28.03	$448K

Holdings After Transaction: Employee Stock Option (right to buy) — 75,507 options (Direct); Common Stock — 167,076 shares (Direct)

Footnotes (3)

F1. 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.
F2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.99 to $29.00, 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.
F3. Shares subject to the option are fully vested and immediately exercisable.

Key Figures

Options exercised: 16,000 shares Exercise price: $13.03 per share Sale: 16,000 shares at $28.03 per share +3 more

6 metrics

Options exercised 16,000 shares November 4, 2026

Exercise price $13.03 per share Options exercised November 4, 2026

Sale 16,000 shares at $28.03 per share November 4, 2026

Options exercised 11,000 shares November 5, 2026

Exercise price $17.99 per share Options exercised November 5, 2026

Sale 12,631 shares at a weighted average price of $28.9913 per share November 5, 2026

Key Terms

Rule 10b5-1 trading plan, weighted average price, Employee Stock Option (right to buy)

3 terms

Rule 10b5-1 trading plan regulatory

"pursuant to a Rule 10b5-1 trading plan adopted by the reporting person"

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.

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.

Employee Stock Option (right to buy) financial

"Employee Stock Option (right to buy)"

FAQ

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

How many AMPH shares did William J. Peters sell?

William J. Peters sold 16,000 shares on November 4, 2026, at $28.03 per share and 12,631 shares on November 5, 2026, at a weighted average price of $28.9913 per share. The November 5 sales were made in multiple transactions at prices from $28.99 to $29.00, inclusive. Both sales were under a Rule 10b5-1 plan adopted March 10, 2026.

How many AMPH options did William J. Peters exercise?

He exercised options covering 16,000 shares on November 4, 2026, at an exercise price of $13.03 per share and options covering 11,000 shares on November 5, 2026, at an exercise price of $17.99 per share.

Were William J. Peters's AMPH options vested?

Both option positions were fully vested and immediately exercisable. The option covering 16,000 shares had an expiration date of March 16, 2030, and the option covering 11,000 shares had an expiration date of March 17, 2031.

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

Form 4 Insider Transactions: What Each Field Means →

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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^*

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)
11/04/2026

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)
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	11/04/2026		M		16,000	A	$13.03	184,707	D
Common Stock	11/04/2026		S⁽¹⁾		16,000	D	$28.03	168,707	D
Common Stock	11/05/2026		M		11,000	A	$17.99	179,707	D
Common Stock	11/05/2026		S⁽¹⁾		12,631	D	$28.9913⁽²⁾	167,076	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)
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)	$13.03	11/04/2026		M			16,000	⁽³⁾	03/16/2030	Common Stock	16,000	$0	7,674	D
Employee Stock Option (right to buy)	$17.99	11/05/2026		M			11,000	⁽³⁾	03/17/2031	Common Stock	11,000	$0	67,833	D

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 March 10, 2026.

2. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.99 to $29.00, 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.

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

	/s/ William J. Peters	11/06/2026
	** 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)

Source: View Original Filing on SEC EDGAR