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Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 TRANSMISSION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Delaware ( State or other jurisdiction of incorporation or organization ) 9715 Key West Avenue ( Address of Principal Executive Offices ) FOR THE FISCAL YEAR ENDED December 31 , 2020 TITLE OF EACH CLASS : Common Stock , $ 0.001 Par Value SUPERNUS PHARMACEUTICALS , INC . ( Exact name of registrant as specified in its charter ) or FOR THE TRANSITION PERIOD FROM COMMISSION FILE NUMBER : 001-35518 Large accelerated filer Non - accelerated filer Rockville MD ( 301 ) 838-2500 ( Registrant's telephone number , including area code ) SECURITIES REGISTERED PURSUANT TO SECTION 12 ( b ) OF THE ACT : Outstanding at February 28 , 2021 Trading Symbol 52,923,107 ☐ ΤΟ SUPN 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 > 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 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 Accelerated filer Smaller reporting company Emerging growth company 20-2590184 ( I.R.S. Employer Identification Number ) 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 20850 ( zip code ) NAME OF EACH EXCHANGE ON WHICH REGISTERED : NASDAQ Stock Market LLC No 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 the definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . ( Check one ) : 1 ■ 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 . Yes No Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Yes No As of June 30 , 2020 , the aggregate market value of the common stock held by non - affiliates of the registrant based on the closing price of the common stock on the NASDAQ Global Market was $ 1,205,174,821 . DOCUMENTS INCORPORATED BY REFERENCE Certain portions of the registrant's definitive Proxy Statement for its 2021 Annual Meeting of Stockholders , which will be filed with the Securities and Exchange Commission not later than 120 days after the end of the registrant's 2020 fiscal year end , are incorporated by reference into Part III of this Annual Report on Form 10 - K .