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Table of Contents 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 UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 Maryland ( Equity Residential ) Illinois ( ERP Operating Limited Partnership ) ( State or other jurisdiction of incorporation or organization ) Two North Riverside Plaza , Chicago , Illinois 60606 ( Address of principal executive offices ) ( Zip Code ) Securities registered pursuant to Section 12 ( b ) of the Act : Title of each class Common Shares of Beneficial Interest , $ 0.01 Par Value ( Equity Residential ) 7.57 % Notes due August 15 , 2026 ( ERP Operating Limited Partnership ) For the transition period from Commission File Number : 1-12252 ( Equity Residential ) Commission File Number : 0-24920 ( ERP Operating Limited Partnership ) EQUITY RESIDENTIAL ERP OPERATING LIMITED PARTNERSHIP ( Exact name of registrant as specified in its charter ) ☐ ☐ ☐ ■ Trading Symbol ( s ) EQR N / A to ■ 13-3675988 ( Equity Residential ) 36-3894853 ( ERP Operating Limited Partnership ) ( I.R.S. Employer Identification No. ) ( 312 ) 474-1300 ( Registrant's telephone number , including area code ) Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Equity Residential Yes No Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . Equity Residential Yes No ERP Operating Limited Partnership 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 . Name of each exchange on which registered New York Stock Exchange New York Stock Exchange Securities registered pursuant to Section 12 ( g ) of the Act : None ( Equity Residential ) Units of Limited Partnership Interest ( ERP Operating Limited Partnership ) ( Title of each class ) Equity Residential Yes No ERP Operating Limited Partnership Yes No 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 ) . Equity Residential Yes No ERP Operating Limited Partnership 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 definitions of " large accelerated filer , " " accelerated filer , " " smaller reporting company , " and " emerging growth company " in Rule 12b - 2 of the Exchange Act . Equity Residential : Large accelerated filer Non - accelerated filer Emerging growth company ERP Operating Limited Partnership : 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 . Equity Residential ERP Operating Limited Partnership Yes No Accelerated filer Smaller reporting company Accelerated filer Smaller reporting company 0 0 ERP Operating Limited Partnership ☐ 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 . | ERP Operating Limited Partnership Equity Residential Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Act ) . Equity Residential Yes No ERP Operating Limited Partnership Yes No The aggregate market value of Common Shares held by non - affiliates of the Registrant was approximately $ 21.7 billion based upon the closing price on June 30 , 2020 of $ 58.82 using beneficial ownership of shares rules adopted pursuant to Section 13 of the Securities Exchange Act of 1934 to exclude voting shares owned by Trustees and Executive Officers , some of whom may not be held to be affiliates upon judicial determination . The number of Common Shares of Beneficial Interest , $ 0.01 par value , outstanding on February 12 , 2021 was 372,663,215 .