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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K 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 Commission File Number : 1-13199 ( SL Green Realty Corp. ) Commission File Number : 33-167793-02 ( SL Green Operating Partnership , L.P. ) SL Green Realty Corp. SL Green Operating Partnership , L.P. Registrant SL Green Realty Corp. SL Green Realty Corp. SL GREEN REALTY CORP . SL GREEN OPERATING PARTNERSHIP , L.P. ( Exact name of registrant as specified in its charter ) SECURITIES REGISTERED PURSUANT TO SECTION 12 ( B ) OF THE ACT : Trading Symbol SLG SLG.PRI Maryland Delaware ( State or other jurisdiction of incorporation or organization ) to 420 Lexington Avenue , New York , NY 10170 ( Address of principal executive offices - Zip Code ) ( 212 ) 594-2700 ( Registrant's telephone number , including area code ) Title of Each Class Common Stock , $ 0.01 par value 6.500 % Series I Cumulative Redeemable Preferred Stock , $ 0.01 par value 13-3956775 13-3960938 ( I.R.S. Employer Identification No. ) 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 Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . SL Green Realty Corp. Yes x No o SL Green Operating Partnership , L.P. Yes o No x Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15 ( d ) of the Act . SL Green Realty Corp. Yes o No X SL Green Operating Partnership , L.P. Yes o No X 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 . SL Green Realty Corp. Yes x No o SL Green Operating Partnership , L.P. Yes x No o 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 ) . SL Green Realty Corp. Yes x No o SL Green Operating Partnership , L.P. Yes x No o Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S - K is not contained herein , and will not be contained , to the best of the registrant's knowledge , in definitive proxy or information statements incorporated by reference in Part III of this Form 10 - K or any amendment to this Form 10 - K . SL Green Realty Corp. O SL Green Operating Partnership , L.P. O 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 . SL Green Realty Corp.