Page 1

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( Mark One ) X 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 to Commission file number : 001-33225 Delaware ( State or other jurisdiction of incorporation or organization ) Great Lakes Dredge & Dock Corporation ( Exact name of registrant as specified in its charter ) 9811 Katy Freeway , Suite 1200 , Houston , TX ( Address of principal executive offices ) Title of each class Common Stock , ( Par Value $ 0.0001 ) CAT 1890 000 ( 346 ) 359-1010 ( Registrant's telephone number , including area code ) Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) . 20-5336063 ( I.R.S. Employer Identification No. ) 77024 ( Zip Code ) GLDD 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 Name of each exchange on which registered Nasdaq Stock Market , LLC 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 Part of 10 - K Part III No X 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 . Large accelerated filer Non - accelerated filer 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 voting stock held by non - affiliates of the Registrant was $ 586,573,144 at June 30 , 2020. The aggregate market value was computed using the closing price of the common stock as of June 30 , 2020 on the Nasdaq Stock Market . ( For purposes of a calculating this amount only , all directors and executive officers of the registrant have been treated as affiliates . ) As of February 19 , 2021 , 65,120,437 shares of Registrant's Common Stock , par value $ .0001 per share , were outstanding . DOCUMENTS INCORPORATED BY REFERENCE Documents Incorporated by Reference Portions of the Proxy Statement to be filed with the Securities and Exchange Commission in connection with the 2021 Annual Meeting of Stockholders .