UNITED STATES
          
          SECURITIES AND EXCHANGE COMMISSION
          
          Washington, D.C. 20549
          SCHEDULE 14A
          
          PROXY STATEMENT PURSUANT TO SECTION 14(a) OF THE
          
          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-11(c) or  ☐ 240.14a-2 | 
Harmony Biosciences Holdings, Inc.
          
          (Name of Registrant as Specified In Its Charter)
          Payment of Filing Fee (Check the appropriate box): 
          | ☒ |  |  | No fee required. | 
| ☐ | Fee computed on table below per Exchange Act Rules 14a-6(i)(1) and 0-11. | ||
|  ☐ |  |  | Fee paid previously with preliminary materials. | 
|  ☐ |  |  | Fee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a-6(i)(1) and
                    0-11. | 

