# EDGAR Filing Document

**Accession Number:** 0001297184
**File Stem:** 0001297184-26-000025
**Filing Date:** 2026-4
**Character Count:** 4995
**Document Hash:** f6f6da14f33575f448b78b1a62372d81
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001297184-26-000025.hdr.sgml**: 20260413

**ACCESSION NUMBER**: 0001297184-26-000025

**CONFORMED SUBMISSION TYPE**: DEFA14A

**PUBLIC DOCUMENT COUNT**: 3

**FILED AS OF DATE**: 20260413

**DATE AS OF CHANGE**: 20260413

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Amphastar Pharmaceuticals, Inc.
- **CENTRAL INDEX KEY:** 0001297184
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **ORGANIZATION NAME:** 03 Life Sciences
- **EIN:** 330702205
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** DEFA14A
- **SEC ACT:** 1934 Act
- **SEC FILE NUMBER:** 001-36509
- **FILM NUMBER:** 26858101

**BUSINESS ADDRESS:**
- **STREET 1:** 11570 SIXTH STREET
- **CITY:** RANCHO CUCAMONGA
- **STATE:** CA
- **ZIP:** 91730
- **BUSINESS PHONE:** 909-980-9484

**MAIL ADDRESS:**
- **STREET 1:** 11570 SIXTH STREET
- **CITY:** RANCHO CUCAMONGA
- **STATE:** CA
- **ZIP:** 91730

#### UNITED STATES

#### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### SCHEDULE 14A INFORMATION

#### PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE<br>SECURITIES EXCHANGE ACT OF 1934
Filed by the Registrant ⌧

Filed by a Party other than the Registrant ◻

Check the appropriate box:

◻Preliminary Proxy Statement

◻**Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))**

◻Definitive Proxy Statement

⌧Definitive Additional Materials

◻Soliciting Material Pursuant to §240.14a-12

**AMPHASTAR PHARMACEUTICALS, INC.**

**(Name of Registrant as Specified In Its Charter)**

Payment of Filing Fee (Check all boxes that apply):

⌧No fee required.

◻ Fee paid previously with preliminary materials.

◻Fee computed in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(4) and 0-11.

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| &nbsp;&nbsp;![GRAPHIC](amph-20260413xdefa14a_bg001.jpg) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Your Vote Counts! Smartphone users Point your camera here and vote without entering a control number For complete information and to vote, visit www.ProxyVote.com Control # V87312-P49656 \*Please check the meeting materials for any special requirements for meeting attendance. AMPHASTAR PHARMACEUTICALS, INC. C/O BROADRIDGE CORPORATE ISSUER SOLUTIONS, INC. P.O. BOX 1342 BRENTWOOD, NY 11717 AMPHASTAR PHARMACEUTICALS, INC. 2026 Annual Meeting Vote by May 31, 2026 11:59 PM ET You invested in AMPHASTAR PHARMACEUTICALS, INC. and it's time to vote! You have the right to vote on proposals being presented at the Annual Meeting. This is an important notice regarding the availability of proxy materials for the stockholder meeting to be held on June 1, 2026. Vote Virtually at the Meeting\* June 1, 2026 11:30 AM, Pacific Time Virtually at: www.virtualshareholdermeeting.com/AMPH2026 Get informed before you vote We encourage you to access and review all of the important information contained in the proxy materials before voting. View the Notice, Proxy Statement and Annual Report online OR you can receive a free paper or email copy of the materials by requesting prior to May 18, 2026. If you would like to request a copy of the materials for this and/or future stockholder meetings, you may (1) visit www.ProxyVote.com, (2) call 1-800-579-1639 or (3) send an email to sendmaterial@proxyvote.com. If sending an email, please include your control number (indicated below) in the subject line. Unless requested, you will not otherwise receive a paper or email copy. |

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| &nbsp;&nbsp;![GRAPHIC](amph-20260413xdefa14a_bg002.jpg) | &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Vote at www.ProxyVote.com Prefer to receive an email instead? While voting on www.ProxyVote.com, be sure to click "Delivery Settings". Voting Items Board Recommends V87313-P49656 THIS IS NOT A VOTABLE BALLOT This is an overview of the proposals being presented at the upcoming stockholder meeting. Please follow the instructions on the reverse side to vote these important matters. 1. To elect three Class I directors to serve until the Company's 2029 annual meeting of stockholders and until each such director's successor is elected and qualified or until such director's earlier death, resignation or removal; Nominees: 1a. David Gaugh For 1b. William J. Peters For 1c. Jacob Liawatidewi For 2. To ratify the appointment of Ernst & Young LLP as the Company's independent registered public accounting firm for its fiscal year ending December 31, 2026; and For 3. To approve, on an advisory basis, the compensation of the Company's named executive officers. For 4. To approve, on an advisory basis, the frequency of future stockholder advisory votes on our named executive officer compensation. 1 Year NOTE: To transact such other business as may properly come before the Annual Meeting or any adjournments or postponements thereof. |

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