William J. Peters - 07 Aug 2026 Form 4 Insider Report for Amphastar Pharmaceuticals, Inc. (AMPH)

Reporting relationship: CFO, EVP & TREASURER, Director
Issuer ticker: AMPH
Reported as of: 07 Aug 2026
Net transaction value: -$183,886
SEC form: 4
Accepted by SEC: 11 Aug 2026, 16:57:01 UTC
Prior SEC filing: 17 Mar 2026
Source filing: View source filing
Reporting owner signature: /s/ William J. Peters

Key filing fact

William J. Peters filed Form 4 for Amphastar Pharmaceuticals, Inc. (AMPH) on 11 Aug 2026.

Key facts

This page summarizes William J. Peters's Form 4 filing for Amphastar Pharmaceuticals, Inc. (AMPH).
3 reported transactions and 1 derivative row are listed below.
Accepted by SEC: 11 Aug 2026, 16:57.

Change

Previous filing in this sequence was filed on 17 Mar 2026.
Current net transaction value: -$183,886.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001263136 Primary reporting owner

PETERS WILLIAM J

Relationship: CFO, EVP & TREASURER, Director
Address: C/O AMPHASTAR PHARMACEUTICALS, INC., 11570 6TH STREET, RANCHO CUCAMONGA
Signature: /s/ William J. Peters
Signature date: 11 Aug 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

AMPH transaction

Common Stock

Options Exercise

Transaction value
Shares: +5,053
Change %: +2.9%
Price: $19.79^*
Shares after: 181,026
Date: 07 Aug 2026
Ownership: Direct
Footnotes: F1

AMPH transaction

Common Stock

Sale

Transaction value: $183,886
Shares: -8,180
Change %: -4.5%
Price: $22.48
Shares after: 172,846
Date: 07 Aug 2026
Ownership: Direct
Footnotes: F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

AMPH transaction Derivative

Employee Stock Option (right to buy)

Options Exercise

Transaction value
Shares: -5,053
Change %: -100%
Price: $0.000000^*
Shares after: 0
Date: 07 Aug 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 5,053
Exercise price: $19.79
Footnotes: F3

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Rule 10b5-1 trading plan

These transactions were reported as open-market trades under a Rule 10b5-1 plan. The plan lets an insider set trading instructions in advance, which can reduce the risk of trading while in possession of material nonpublic information.

Original filing language: transaction made pursuant to a contract, instruction, or written plan intended to satisfy Rule 10b5-1(c).

Explanation of responses 3 footnotes

Footnote F1

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

Footnote 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.

Footnote F3

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