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( Mark One ) Annual Report Pursuant to Section 13 or 15 ( d ) of the Securities Exchange Act of 1934 Maryland 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 FORM 10 - K ( Brandywine Realty Trust ) Delaware ( Brandywine Operating Partnership , L.P. ) ( State or Other Jurisdiction of Incorporation or Organization ) Title of each class Common Shares of Beneficial Interest For the fiscal year ended December 31 , 2020 OR Brandywine Realty Trust Brandywine Operating Partnership , L.P. For the transition period from_ to Brandywine Realty Trust Brandywine Operating Partnership , L.P. ( Exact name of registrant as specified in its charter ) Securities registered pursuant to section 12 ( b ) of the Act : Brandywine Realty Trust Brandywine Operating Partnership , L.P. 001-9106 000-24407 ( Commission file number ) 2929 Walnut Street Suite 1700 Philadelphia , PA 19104 ( Address of principal executive offices ) ( Zip Code ) ( 610 ) 325-5600 ( Registrant's telephone number , including area code ) Trading Symbol ( s ) Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . BDN Yes > No 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 . Brandywine Realty Trust Yes No Yes No Brandywine Operating Partnership , L.P. 23-2413352 Yes No Yes > No 23-2862640 ( I.R.S. Employer Identification Number ) 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 NYSE 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 ) .