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Table of Contents 0 UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON , D.C. 20549 ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( D ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE FISCAL YEAR ENDED DECEMBER 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( D ) OF THE SECURITIES EXCHANGE ACT OF 1934 FOR THE TRANSITION PERIOD FROM ΤΟ COMMISSION FILE NUMBER 001-36485 FORM 10 - K DELAWARE ( STATE OR OTHER JURISDICTION OF INCORPORATION OR ORGANIZATION ) Title of Each Class Common Stock , par value $ 0.0001 per share ARDELYX , INC . ( EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER ) A Large accelerated filer Non - accelerated filer 26-1303944 ( I.R.S. EMPLOYER IDENTIFICATION NO . ) 34175 ARDENWOOD BLVD . , FREMONT , CALIFORNIA 94555 400 FIFTH AVE . , SUITE 210 , WALTHAM , MASSACHUSETTS 02451 ( ADDRESS OF PRINCIPAL EXECUTIVE OFFICES , INCLUDING ZIP CODE ) ( 510 ) 745-1700 ( REGISTRANT'S TELEPHONE NUMBER , INCLUDING AREA CODE ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) ARDX 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 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 Name of Each Exchange on Which Registered The Nasdaq Global Market 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 the definition of " large accelerated filer " , " accelerated filer " , " smaller reporting company " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Accelerated filer Small 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 . The number of shares of Registrant's Common Stock outstanding as of March 3 , 2021 , was 98,680,264 . DOCUMENTS INCORPORATED BY REFERENCE : 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 , June 30 , 2020 , based on the last reported sales price of the Registrant's common stock of $ 6.92 per share was $ 611,732,242 . Portions of the Registrant's Definitive Proxy Statement for its 2021 Annual Meeting of Stockholders , which will be filed with the Commission within 120 days of December 31 , 2020 , the close of the Registrant's 2020 fiscal year , are incorporated by reference into Part III of this Report .