Key facts
- This page summarizes William J. Peters's Form 4 filing for Amphastar Pharmaceuticals, Inc. (AMPH).
- 6 reported transactions and 2 derivative rows are listed below.
- Accepted by SEC: 06 Nov 2026, 16:17.
William J. Peters - 04 Nov 2026 Form 4 Insider Report for Amphastar Pharmaceuticals, Inc. (AMPH)
- Reporting relationship
- CFO, EVP & TREASURER, Director
- Issuer ticker
- AMPH
- Reported as of
- 04 Nov 2026
- Net transaction value
- -$814,669
- SEC form
- 4
- Accepted by SEC
- 06 Nov 2026, 16:17:08 UTC
- Prior SEC filing
- 23 Sep 2026
- Source filing
- View source filing
- Reporting owner signature
- /s/ William J. Peters
Source evidence
Original filing metadata and source links for verification.
4 source fields
Reporting owner
1 detail
Filing notes and source
Key filing fact
William J. Peters filed Form 4 for Amphastar Pharmaceuticals, Inc. (AMPH) on 06 Nov 2026.
Change
- Previous filing in this sequence was filed on 23 Sep 2026.
- Current net transaction value: -$814,669.
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
View source filing
Ownership activity is grounded in SEC Form 4 disclosures.
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
- 06 Nov 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
- +16,000
- Change %
- +9.5%
- Price
- $13.03*
- Shares after
- 184,707
- Date
- 04 Nov 2026
- Ownership
- Direct
AMPH
transaction
Common Stock
Sale
- Transaction value
- -$448,480
- Shares
- -16,000
- Change %
- -8.7%
- Price
- $28.03
- Shares after
- 168,707
- Date
- 04 Nov 2026
- Ownership
- Direct
- Footnotes
- F1
AMPH
transaction
Common Stock
Options Exercise
- Transaction value
- Shares
- +11,000
- Change %
- +6.5%
- Price
- $17.99*
- Shares after
- 179,707
- Date
- 05 Nov 2026
- Ownership
- Direct
AMPH
transaction
Common Stock
Sale
- Transaction value
- -$366,189
- Shares
- -12,631
- Change %
- -7%
- Price
- $28.99
- Shares after
- 167,076
- Date
- 05 Nov 2026
- Ownership
- Direct
- Footnotes
- F1, 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
- -16,000
- Change %
- -68%
- Price
- $0.000000*
- Shares after
- 7,674
- Date
- 04 Nov 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 16,000
- Exercise price
- $13.03
- Footnotes
- F3
AMPH
transaction
Derivative
Employee Stock Option (right to buy)
Options Exercise
- Transaction value
- Shares
- -11,000
- Change %
- -14%
- Price
- $0.000000*
- Shares after
- 67,833
- Date
- 05 Nov 2026
- Ownership
- Direct
- Underlying class
- Common Stock
- Underlying amount
- 11,000
- Exercise price
- $17.99
- 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
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 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.
Footnote F3
Shares subject to the option are fully vested and immediately exercisable.