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UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington , D.C. 20549 FORM 10 - K ( Mark One ) ☑ 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 . to Commission File Number : 001-35653 Delaware SUNOCO LP ( Exact name of registrant as specified in its charter ) ( State or other jurisdiction of incorporation or organization ) 30-0740483 ( I.R.S. Employer Identification Number ) Title of each class 8111 Westchester Drive , Suite 400 , Dallas , Texas 75225 ( Address of principal executive offices , including zip code ) Registrant's telephone number , including area code : ( 214 ) 981-0700 Securities registered pursuant to Section 12 ( b ) of the Act : Common Units Representing Limited Partner Interests Trading Symbol ( s ) . SUN Name of each exchange on which registered 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 . Yes ý 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 . Yes ☐ 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 ☐ Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Registration 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 ý 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 . Large accelerated filer Ў Non - accelerated filer ☐ 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 . □ 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 At June 30 , 2020 , the aggregate market value of common units representing limited partner interests held by non - affiliates of the registrant was approximately $ 1.2 billion based upon the closing price of its common units on the New York Stock Exchange . The registrant had 83,343,702 common units representing limited partner interests and 16,410,780 Class C units representing limited partner interests outstanding at February 12 , 2021 .