UNITED STATES
 SECURITIES AND EXCHANGE COMMISSION
 Washington, D.C. 20549

 FORM 10-K/A
 (Amendment No.1)

 (Mark One)
 ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES AND EXCHANGE ACT OF 1934
 For the fiscal year ended December 31, 2023
 OR
 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
 For the transition period from to
 Commission File Number: 001-39450

 HARMONY BIOSCIENCES HOLDINGS, INC.
 (Exact name of registrant as specified in its charter)

 Delaware

 82-2279923

 (State or other jurisdiction of

 (I.R.S. Employer

 incorporation or organization)

 Identification No.)

 630 W. Germantown Pike, Suite 215, Plymouth Meeting, PA

 19462

 (Address of principal executive offices)

 (Zip Code)

 ( 484) 539-9800

 (Registrant's telephone number, including area code)

 Securities registered pursuant to Section 12(b) of the Act:

 Trading

 Name of each exchange

 Title of each class

 Symbol(s)

 on which registered

 Common Stock, par value $0.00001 value per share

 HRMY

 The Nasdaq Stock Market LLC

 (Nasdaq Global Market)

 Securities registered pursuant to Section 12(g) of the Act: None
 Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes No
 Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes No
 Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes No
 Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes No
 Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule 12b-2 of the Exchange Act:

 Large accelerated filer

 Accelerated filer

 Non-accelerated filer

 Smaller reporting company

 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.
 Indicate by check mark whether the registrant has filed a report on and attestation to its management's assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.
 If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.
 Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant's executive officers during the relevant recovery period pursuant to §240.10D-1(b).
 Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes No
 The aggregate market value of the voting and non-voting stock held by non-affiliates of the Registrant, as of June 30, 2023, the last business day of the registrant's most recently completed second fiscal quarter, was $ 1,174.5 million. As of February 16, 2024, the registrant had 56,769,081 shares of common stock, $0.00001 par value per share, outstanding.

 Auditor Firm ID: 34 Auditor Name: Deloitte & Touche LLP Auditor Location: Philadelphia, Pennsylvania

 DOCUMENTS INCORPORATED BY REFERENCE
 Portions of the registrant's definitive proxy statement relating to its 2024 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission within 120 days after the end of the fiscal year ended December 31, 2023, are incorporated herein by reference in Part III where indicated.

 Explanatory Note
 Harmony Biosciences Holdings, Inc. (the "Company") is filing this Amendment No. 1 on Form 10-K/A (this "Amendment") to its Annual Report on Form 10-K for the fiscal year ended December 31, 2023, which was originally filed with the Securities and Exchange Commission (the "SEC") on February 22, 2024 (the "Original Filing"). This Amendment is being filed to revise Part II "Item 9B. Other Information" by adding Rule 10b5-1 trading arrangements entered into or modified by certain of our officers during the quarter ended December 31, 2023.
 In addition, as required by Rule 12b-15 under the Securities Exchange Act of 1934, as amended ("Exchange Act"), new certifications of our principal executive officer and principal financial officer are filed as exhibits to this Amendment under Item 15 of Part IV hereof. Because no financial statements have been included in this Amendment and this Amendment does not contain or amend any disclosure with respect to Items 307 and 308 of Regulation S-K, paragraphs 3, 4 and 5 of the certifications have been omitted. The Company is also not including new certifications under Section 1350 of Chapter 63 of Title 18 of the United States Code (18 U.S.C. 1350) (Section 906 of the Sarbanes-Oxley Act of 2002), as no financial statements are being filed with this Amendment.
 This Amendment does not otherwise change or update any of the disclosures set forth in the Original Form 10-K and does not otherwise reflect any events occurring after the filing of the Original Form 10-K. No changes have been made to the financial statements of the Company as contained in the Original Filing. Accordingly, the Amendment should be read in conjunction with the Original Form 10-K and the Company's filings made with the SEC subsequent to the filing of the Original Form 10-K. Capitalized terms used herein and not otherwise defined are defined as set forth in the Original Form 10-K.

 Item 9B. Other Information.
 (a) None.
 (b) On November 2, 2023, Sandip Kapadia, Chief Financial Officer and Chief Administrative Officer of the Company, modified a Rule 10b5-1 trading arrangement, originally adopted on February 22, 2023, to change the amount of shares to be sold related to the exercise of options under the plan. The modified plan is intended to satisfy the affirmative defense of Rule 10b5-1(c) and provides for the sale of up to 30,000 shares of the Company's common stock until April 3, 2024. On November 2, 2023, Mr. Kapadia also adopted a Rule 10b5-1 trading arrangement that is intended to satisfy the affirmative defense of Rule 10b5-1(c) and provides for the sale of up to 55,000 shares of the Company's common stock related to the exercise of options beginning on April 4, 2024 and until December 30, 2024.
 On December 7, 2023, Jeffrey Dierks, Chief Commercial Officer of the Company, adopted a Rule 10b5-1 trading arrangement that is intended to satisfy the affirmative defense of Rule 10b5-1(c) for the sale of up to 16,097 shares of the Company's common stock until June 30, 2024 related to the exercise of options.
 During the quarter ended December 31, 2023, no director or officer of the Company terminated a "Rule 10b5-1 trading arrangement" or " non-Rule 10b5-1 trading arrangement," as each term is defined in Item 408(a) of Regulation S-K.

 Item 15. Exhibits, Financial Statement Schedules.
 (a)(3) Exhibits.
 The documents set forth below are filed herewith or incorporated herein by reference to the location indicated.
 EXHIBIT INDEX
 Exhibit

 Incorporated by Reference

 Filed

 No.

 Exhibit Description

 Form

 Date

 Number

 Herewith

 31.1

 Certification of Chief Executive Officer pursuant to Rules 13a-14(a) and 15d-14(a) of the Securities Exchange Act of 1934, as amended, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

 X

 31.2

 Certification of Chief Financial Officer pursuant to Rules 13a-14(a) and 15d-14(a) of the Securities Exchange Act of 1934, as amended, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

 X

 X

 Signatures
 Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

 HARMONY BIOSCIENCES HOLDINGS, INC.

 By:

 /s/ Jeffrey M. Dayno

 Name:

 Jeffrey M. Dayno

 Title:

 President, Chief Executive Officer and Director (principal executive officer)

 Date: February 28, 2024