1. Home
  2. AMPH

as of 03-26-2026 3:59pm EST

$19.51
$0.06
-0.31%
Stocks Health Care Biotechnology: Pharmaceutical Preparations Nasdaq

Amphastar Pharmaceuticals Inc is a bio-pharmaceutical company focusing on developing, manufacturing, marketing, and selling technically challenging generic and proprietary injectable, inhalation, and intranasal products, as well as insulin active pharmaceutical ingredient, or insulin API products. The company's finished products are used in hospital or urgent care clinical settings and are contracted and distributed through group purchasing organizations and drug wholesalers. The company has one reportable segment pharmaceutical products. Geographically the business presence of the firm is seen in the United States, China and France of which the U.S. accounts for the majority of the revenue.

Founded: 1996 Country:
United States
United States
Employees: N/A City: RANCHO CUCAMONGA
Market Cap: 1.2B IPO Year: 2005
Target Price: $30.29 AVG Volume (30 days): 594.4K
Analyst Decision: Buy Number of Analysts: 7
Dividend Yield:
N/A
Dividend Payout Frequency: N/A
EPS: 2.03 EPS Growth: -33.66
52 Week Low/High: $17.03 - $31.26 Next Earning Date: 05-06-2026
Revenue: $719,887,000 Revenue Growth: -1.65%
Revenue Growth (this year): 7.19% Revenue Growth (next year): 4.76%
P/E Ratio: 9.64 Index: N/A
Free Cash Flow: 121.2M FCF Growth: -29.66%

AI-Powered AMPH Daily Prediction

Machine learning model trained on 25+ technical indicators

Updated 20 hours ago

AI Recommendation

hold
Model Accuracy: 74.23%
74.23%
Confidence

Disclaimer: This prediction is generated by an AI model and should not be considered as financial advice. Always conduct your own research and consult with financial professionals before making investment decisions.

Earnings Transcripts

SEC 8-K filings with transcript text

View All
2025
Q4

Q4 2025 Earnings

8-K SELL

Feb 26, 2026 · 100% conf.

AI Prediction SELL

1D

-7.05%

$24.62

Act: -24.42%

5D

-7.89%

$24.40

Act: -22.84%

20D

-12.04%

$23.30

Price: $26.49 Prob +5D: 0% AUC: 1.000
0001297184-26-000007

Amphastar Pharmaceuticals, Inc._February 26, 2026 0001297184false00012971842026-02-262026-02-26 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): February 26, 2026 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On February 26, 2026, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months and fiscal year ended December 31, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No. ​ ​ ​ Description

99.1 ​ Press release, dated February 26, 2026, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: February 26, 2026 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2025
Q3

Q3 2025 Earnings

8-K

Nov 6, 2025

0001297184-25-000062

Amphastar Pharmaceuticals, Inc._November 6, 2025 0001297184falseDE00012971842025-11-062025-11-06 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): November 6, 2025 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On November 6, 2025, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended September 30, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated November 6, 2025, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: November 6, 2025 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2025
Q2

Q2 2025 Earnings

8-K

Aug 7, 2025

0001297184-25-000048

0001297184falseDE00012971842025-08-072025-08-07 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): August 7, 2025 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On August 7, 2025, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended June 30, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated August 7, 2025, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: August 7, 2025 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2025
Q1

Q1 2025 Earnings

8-K

May 7, 2025

0001297184-25-000025

0001297184false00012971842025-05-072025-05-07 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): May 7, 2025 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act: ​ T

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On May 7, 2025, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended March 31, 2025. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated May 7, 2025, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: May 7, 2025 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2024
Q4

Q4 2024 Earnings

8-K

Feb 27, 2025

0001297184-25-000003

0001297184falseDE00012971842025-02-272025-02-27 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): February 27, 2025 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On February 27, 2025, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months and fiscal year ended December 31, 2024. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated February 27, 2025, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: February 27, 2025 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2024
Q3

Q3 2024 Earnings

8-K

Nov 6, 2024

0001297184-24-000055

0001297184falseDE00012971842024-11-062024-11-06 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): November 6, 2024 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On November 6, 2024, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended September 30, 2024. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated November 6, 2024, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: November 6, 2024 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2024
Q2

Q2 2024 Earnings

8-K

Aug 7, 2024

0001297184-24-000045

0001297184falseDE00012971842024-08-072024-08-07 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): August 7, 2024 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On August 7, 2024, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended June 30, 2024. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated August 7, 2024, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: August 7, 2024 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2024
Q1

Q1 2024 Earnings

8-K

May 8, 2024

0001297184-24-000033

0001297184false00012971842024-05-082024-05-08 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): May 8, 2024 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act: ​ T

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On May 8, 2024, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended March 31, 2024. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated May 8, 2024, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: May 8, 2024 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2023
Q4

Q4 2023 Earnings

8-K

Feb 28, 2024

0001297184-24-000004

0001297184falseDE00012971842024-02-282024-02-28 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): February 28, 2024 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On February 28, 2024, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months and fiscal year ended December 31, 2023. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated February 28, 2024, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: February 28, 2024 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2023
Q3

Q3 2023 Earnings

8-K

Nov 8, 2023

0001297184-23-000079

0001297184falseDE00012971842023-11-082023-11-08 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): November 8, 2023 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On November 8, 2023, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended September 30, 2023. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated November 8, 2023, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: November 8, 2023 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2023
Q2

Q2 2023 Earnings

8-K

Aug 8, 2023

0001297184-23-000063

0001297184falseDE00012971842023-08-082023-08-08 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): August 8, 2023 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On August 8, 2023, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended June 30, 2023. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated August 8, 2023, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: August 8, 2023 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2023
Q1

Q1 2023 Earnings

8-K

May 9, 2023

0001297184-23-000046

0001297184false00012971842023-05-092023-05-09 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): May 9, 2023 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act: ​ T

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On May 9, 2023, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended March 31, 2023. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated May 9, 2023, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: May 9, 2023 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2022
Q4

Q4 2022 Earnings

8-K

Feb 28, 2023

0001297184-23-000012

0001297184falseDE00012971842023-02-282023-02-28 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): February 28, 2023 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 ​ ​ ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On February 28, 2023, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months and fiscal year ended December 31, 2022. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated February 28, 2023, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: February 28, 2023 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2022
Q3

Q3 2022 Earnings

8-K

Nov 7, 2022

0001297184-22-000053

0001297184falseDE00012971842022-11-072022-11-07 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): November 7, 2022 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On November 7, 2022, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended September 30, 2022. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated November 7, 2022, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: November 7, 2022 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer, Executive Vice President and Treasurer

​ ​ ​

2022
Q2

Q2 2022 Earnings

8-K

Aug 8, 2022

0001297184-22-000041

0001297184falseDE00012971842022-08-082022-08-08 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): August 8, 2022 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On August 8, 2022, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended June 30, 2022. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated August 8, 2022, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: August 8, 2022 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer and Executive Vice President

​ ​ ​

2022
Q1

Q1 2022 Earnings

8-K

May 9, 2022

0001297184-22-000026

0001297184false00012971842022-05-092022-05-09 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): May 9, 2022 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act: ​ T

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On May 9, 2022, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended March 31, 2022. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated May 9, 2022, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: May 9, 2022 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer and Senior Vice President

​ ​ ​

2021
Q4

Q4 2021 Earnings

8-K

Mar 10, 2022

0001297184-22-000003

0001297184falseDE00012971842022-03-102022-03-10 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): March 10, 2022 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On March 10, 2022, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months and fiscal year ended December 31, 2021. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated March 10, 2022, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: March 10, 2022 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer and Executive Vice President

​ ​ ​

2021
Q3

Q3 2021 Earnings

8-K

Nov 8, 2021

0001297184-21-000062

0001297184falseDE00012971842021-11-082021-11-08 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): November 8, 2021 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On November 8, 2021, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended September 30, 2021. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated November 8, 2021, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: November 8, 2021 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer and Executive Vice President

​ ​ ​

2021
Q2

Q2 2021 Earnings

8-K

Aug 9, 2021

0001297184-21-000046

0001297184falseDE00012971842021-08-092021-08-09 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): August 9, 2021 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act:

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On August 9, 2021, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended June 30, 2021. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated August 9, 2021, issued by Amphastar Pharmaceuticals, Inc.

104 ​ Cover Page Interactive Data File (embedded within the Inline XBRL document)

​ ​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: August 9, 2021 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer and Executive Vice President

​ ​ ​

2021
Q1

Q1 2021 Earnings

8-K

May 6, 2021

0001297184-21-000022

0001297184false00012971842021-05-062021-05-06 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(d) OF THE

SECURITIES EXCHANGE ACT OF 1934

​ Date of Report (Date of earliest event Reported): May 6, 2021 ​ Amphastar Pharmaceuticals, Inc. (Exact Name of Registrant as Specified in Charter) ​ ​

Delaware 001-36509 33-0702205

(State or Other Jurisdiction of Incorporation) (Commission File Number) (I.R.S. Employer Identification Number)

​ ​

11570 6th Street ​

Rancho Cucamonga, California 91730

(Address of Principal Executive Offices) (Zip Code)

​ Registrant's telephone number, including area code: (909) 980-9484 Not Applicable (Former name or former address, if changed since last report) Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions: ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act: ​ T

Title of each class ​ Trading Symbol(s) ​ Name of each exchange on which registered

Common Stock, par value $0.0001 per share ​

AMPH

​ The NASDAQ Stock Market LLC

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ◻ ​ ​ ​ ​

Item 2.02. Results of Operations and Financial Condition. ​ On May 6, 2021, Amphastar Pharmaceuticals, Inc. issued a press release announcing its financial results for the three months ended March 31, 2021. A copy of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K. ​ The information in this Current Report on Form 8-K, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits: ​ ​

Exhibit No.

Description

99.1 ​ Press release, dated May 6, 2021, issued by Amphastar Pharmaceuticals, Inc.

​ ​

SIGNATURE

​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

Date: May 6, 2021 Amphastar Pharmaceuticals, Inc.

​ ​

​ By: /s/ WILLIAM J. PETERS

​ ​ William J. Peters

​ ​ Chief Financial Officer and Senior Vice President

​ ​ ​

Share on Social Networks: