Page 1

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 March 31 , 2021 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ADVANCED DRAINAGE SYSTEMS , INC . ( Exact name of registrant as specified in its charter ) Delaware ( State or other jurisdiction of incorporation or organization ) to COMMISSION FILE NO .: 001-36557 0 4640 Trueman Boulevard , Hilliard , Ohio 43026 ( Address of principal executive offices and zip code ) ( 614 ) 658-0050 ( Registrant's telephone number , including area code ) 51-0105665 ( I.R.S. Employer Identification Number ) Securities registered pursuant to Section 12 ( b ) of the Act : Common Stock , $ 0.01 par value per share Trading Symbol ( s ) WMS Title of Each Class Common Stock , $ 0.01 par value per share 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 风 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 区 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 New York Stock Exchange 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 , 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 ) Large Accelerated Filer Non - Accelerated Filer 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 . Accelerated Filer Smaller Reporting Company 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 F - 1 No 风 Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . Yes The aggregate market value of the shares of common stock held by non - affiliates of the registrant ( treating all executive officers and directors of the registrant , for this purpose , as affiliates of the registrant ) was $ 3,115 million as of September 30 , 2020 , the last business day of the registrant's most recently completed second fiscal quarter , based on the reported closing price of the shares of common stock as reported on the New York Stock Exchange on September 30 , 2020 . As of May 18 , 2021 , the registrant had 71,591,660 shares of common stock outstanding . The shares of common stock trade on the New York Stock Exchange under the ticker symbol " WMS . " In addition , as of May 18 , 2021 , 382,895 shares of unvested restricted common stock were outstanding and 19,273,951 shares of ESOP preferred stock , convertible into 14,825,523 shares of common stock , were outstanding . As of May 18 , 2021 , 86,800,078 shares of common stock were outstanding , inclusive of outstanding shares of unvested restricted common stock and on an as - converted basis with respect to the outstanding shares of ESOP preferred stock . DOCUMENTS INCORPORATED BY REFERENCE