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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , DC 20549 ( Mark One ) ANNUAL REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended 12/31/2020 . OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to FORM 10 - K Delaware ( State or Other Jurisdiction of Incorporation or Organization ) Title of each class Common Stock , par value $ .01 per share Commission file number 001-32147 GREENHILL & CO INC . ( Exact Name of Registrant as Specified in its Charter ) 1271 Avenue of the Americas New rk , New York ( Address of Principal Executive Offices ) 51-0500737 ( I.R.S. Employer Identification No. ) Registrant's telephone number , including area code : ( 212 ) 389-1500 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) . GHL Yes ¨ No p No p 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 . Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 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 p No " 10020 ( ZIP Code ) Non - accelerated filer * 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 p 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 ) : Large accelerated filer Accelerated Filer þ 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 ý The aggregate market value of the common stock held by non - affiliates of the registrant , computed by reference to the closing price as of the last business day of the registrant's most recently completed second fiscal quarter , June 30 , 2020 , was approximately $ 141 million . The registrant has no non voting stock . As of February 22 , 2021 , there were 19,511,810 shares of the registrant's common stock outstanding . DOCUMENTS INCORPORATED BY REFERENCE Portions of the Registrant's definitive proxy statement to be delivered to stockholders in connection with the 2021 annual meeting of stockholders to be held on April 27 , 2021 are incorporated by reference in response to Part III of this Report .