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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 For the fiscal year ended September 30 , 2021 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 001-35839 ENANTA PHARMACEUTICALS , INC . ( Exact name of registrant as specified in its charter ) DELAWARE ( State or other jurisdiction of incorporation or organization ) Large accelerated filer Non - accelerated filer 2834 ( Primary Standard Industrial Classification Code Number ) 500 Arsenal Street Watertown , Massachusetts 02472 ( 617 ) 607-0800 Title of each class Common Stock , par value $ 0.01 per share 04-3205099 ( I.R.S. Employer Identification Number ) ( Address , including zip code , and telephone number , including area code , of registrant's principal executive offices ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) Name of each exchange on which registered NASDAQ ENTA 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 No 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 , 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 : 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 . 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 registrant's common stock held by non - affiliates of the registrant as of the last business day of the registrant's most recently completed second fiscal quarter , March 31 , 2021 , based on the last reported sale price of the registrant's common stock of $ 49.32 per share was $ 864,668,968 . The number of shares of the registrant's Common Stock , $ 0.01 par value , outstanding as of November 1 , 2021 was 20,324,795 shares . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's Definitive Proxy Statement for its 2022 Annual Meeting of Stockholders scheduled to be held on March 3 , 2022 , which Definitive Proxy will be filed with the Securities and Exchange Commission not later than 120 days after the registrant's fiscal year end of September 30 , 2021 are incorporated by reference into Part III of this Form 10 - K .