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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 For the transition period from Title of Each Class Common Stock , $ 0.01 par value UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 Maryland ( UDR , Inc. ) Delaware ( United Dominion Realty , L.P. ) ( State or other jurisdiction of incorporation or organization ) UDR , Inc. United Dominion Realty , L.P. 1745 Shea Center Drive , Suite 200 , Highlands Ranch , Colorado 80129 ( Address of principal executive offices ) ( zip code ) Registrant's telephone number , including area code : ( 720 ) 283-6120 Securities registered pursuant to Section 12 ( b ) of the Act : Trading Symbol ( s ) UDR Securities registered pursuant to Section 12 ( g ) of the Act : None ( Title of Class ) Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . Commission file number 1-10524 ( UDR , Inc. ) Commission file number 333-156002-01 ( United Dominion Realty , L.P. ) UDR , Inc. United Dominion Realty , L.P. ( Exact name of registrant as specified in its charter ) to UDR , Inc. United Dominion Realty , L.P. 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 Yes United Dominion Realty , L.P .: Large Accelerated Filer Yes Yes UDR , Inc. United Dominion Realty , L.P. Accelerated Filer Accelerated Filer 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 . UDR , Inc. United Dominion Realty , L.P. Yes þ Yes þ Yes þ Yes þ 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 ) . UDR , Inc. United Dominion Realty , L.P. Non - Accelerated Filer Non - Accelerated Filer þ 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 .: UDR , Inc .: Large Accelerated Filer þ 54-0857512 54-1776887 UDR , Inc. United Dominion Realty , L.P. Indicate by check mark whether the registrant is a shell company ( as defined in Rule 12b - 2 of the Exchange Act ) . ( I.R.S. Employer Identification No. ) Yes þ Yes Name of Each Exchange on Which Registered New York Stock Exchange No □ No þ Yes Yes No þ No þ No □ No □ DOCUMENTS INCORPORATED BY REFERENCE 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 . No □ No □ 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 . Smaller Reporting Company Emerging Growth Company No No þ Smaller Reporting Company Emerging Growth Company No þ No þ The aggregate market value of the shares of common stock of UDR , Inc. held by non - affiliates on June 30 , 2020 was approximately $ 5.8 billion . This calculation excludes shares of common stock held by the registrant's officers and directors and each person known by the registrant to beneficially own more than 5 % of the registrant's outstanding shares , as such persons may be deemed to be affiliates . This determination of affiliate status should not be deemed conclusive for any other purpose . As of February 16 , 2021 , there were 296,820,995 shares of UDR , Inc.'s common stock outstanding . There is no public trading market for the partnership units of United Dominion Realty , L.P. As a result , an aggregate market value of the partnership units of United Dominion Realty , L.P. cannot be determined .