Amphastar officer proposes $448K share sale

William J Peters' two earlier common-share sales were listed at $183,886.40 on August 7, 2026 and $103,475.00 on September 21, 2026.

Available on EDGAR 11/04/2026 - 04:09 PM EST Accepted by SEC EDGAR 11/04/2026 - 04:09 PM EST Learn about SEC filing dates

Rhea-AI Filing Summary

Amphastar Pharmaceuticals, Inc. officer William J Peters reported a proposed sale of 16,000 common shares through UBS Financial Services, Inc., with an aggregate market value of $448,480.00 and November 4, 2026 listed as the sale date. The notice lists 16,000 shares as acquired from the issuer through an exercise of stock options for cash on November 4, 2026. It also records earlier sales of 8,180 shares on August 7, 2026 and 4,139 shares on September 21, 2026.

Key Figures

Proposed common shares for sale: 16,000 shares Aggregate market value: $448,480.00 Shares outstanding: 42,537,944 shares +4 more

7 metrics

Proposed common shares for sale 16,000 shares Sale listed for November 4, 2026

Aggregate market value $448,480.00 Proposed sale

Shares outstanding 42,537,944 shares Issuer shares outstanding

Earlier shares sold 8,180 shares August 7, 2026

Earlier sale value $183,886.40 August 7, 2026

Earlier shares sold 4,139 shares September 21, 2026

Earlier sale value $103,475.00 September 21, 2026

Key Terms

Rule 144, Exercise of Stock Options, attorney-in-fact

3 terms

Rule 144 regulatory

"paragraph (a) of Rule 144"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Exercise of Stock Options financial

"Exercise of Stock Options"

attorney-in-fact regulatory

"as attorney-in-fact for William J Peters"

An attorney-in-fact is the person or entity given legal authority through a power of attorney to act on behalf of another for specific tasks, such as signing documents, voting shares, or handling transactions. For investors, this matters because it lets a trusted representative make timely decisions or complete paperwork when the owner cannot, much like handing keys to someone to run errands on your behalf—so checks on scope and limits of that authority are important.

FAQ

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

How many AMPH shares is William J Peters proposing to sell?

William J Peters reported a proposed sale of 16,000 common shares, with an aggregate market value of $448,480.00. November 4, 2026 is listed as the sale date, and UBS Financial Services, Inc. is listed as the broker.

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

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Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK	0001263136
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	Amphastar Pharmaceuticals, Inc.
SEC File Number	001-36509
Address of Issuer	11570 SIXTH STREET RANCHO CUCAMONGA CALIFORNIA 91730
Phone	909-980-9484
Name of Person for Whose Account the Securities are To Be Sold	PETERS WILLIAM J
See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.
Relationship to Issuer	Officer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	UBS Financial Services, Inc. 1000 Harbor Blvd 3rd Floor Weehawken NJ 07086	16000	448480.00	42537944	11/04/2026	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	11/04/2026	Exercise of Stock Options	Issuer			16000	11/04/2026	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
William J Peters 11570 Sixth Street Rancho Cucamonga CA 91730	Common	08/07/2026	8180	183886.40
William J Peters 11570 Sixth Street, Rancho Cucamonga CA 91730	Common	09/21/2026	4139	103475.00

144: Remarks and Signature

Remarks
Date of Notice	11/04/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	03/10/2026
ATTENTION:
The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.
Signature	/s/ UBS Financial Services Inc, as attorney-in-fact for William J Peters
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)