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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 December 31 , 2020 OR TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Commission File Number 1-9317 Maryland ( State or Other Jurisdiction of Incorporation or Organization ) EQUITY COMMONWEALTH ( Exact Name of Registrant as Specified in Its Charter ) Two North Riverside Plaza , Suite 2100 , Chicago , IL ( Address of Principal Executive Offices ) Securities registered pursuant to Section 12 ( b ) of the Act : Title Of Each Class Large accelerated filer Non - accelerated filer ( 312 ) 646-2800 ( Registrant's Telephone Number , Including Area Code ) Common Shares of Beneficial Interest 6.50 % Series D Cumulative Convertible Preferred Shares of Beneficial Interest Trading Symbol EQC EQCpD 04-6558834 ( IRS Employer Identification No. ) X O 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 ý No o 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 o No ý 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 ý No o 60606 ( Zip Code ) 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 y No o Name of Each Exchange On Which Registered New York Stock Exchange New York Stock Exchange 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 . 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 . o 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 voting common shares of beneficial ownership , $ 0.01 par value , or common shares , of the registrant held by non - affiliates was approximately $ 3.8 billion based on the $ 32.20 closing price per common share on the New York Stock Exchange on June 30 , 2020. For purposes of calculating the aggregate market value of shares held by non - affiliates , we have assumed that all outstanding shares are held by non - affiliates , except for shares held by each of our trustees , executive officers , and any 10 % or greater stockholders . These assumptions should not be deemed to constitute an admission that all trustees , executive officers , and 10 % or greater stockholders are , in fact , affiliates of our company , or that there are not other persons who may be deemed to be affiliates of our company . Further information concerning shareholdings of our trustees , officers , and principal stockholders is included or incorporated by reference in Part III , Item 12 of this Annual Report on Form 10 - K . Number of registrant's common shares outstanding as of February 5 , 2021 : 121,645,021 . DOCUMENTS INCORPORATED BY REFERENCE Certain Information required by Items 10 , 11 , 12 , 13 and 14 of Part III of this Annual Report on Form 10 - K is incorporated herein by reference to the definitive Proxy Statement for the 2021 Annual Meeting of Shareholders , or the definitive Proxy Statement , which Equity Commonwealth intends to file no later than 120 days after the end of its fiscal year ended December 31 , 2020 .