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OR 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 TRANSITION REPORT PURSUANT TO SECTION 13 OR 15 ( d ) OF THE SECURITIES EXCHANGE ACT OF 1934 Delaware from to Commission File Number 1-3876 HOLLYFRONTIER CORPORATION ( Exact name of registrant as specified in its charter ) ( State or other jurisdiction of incorporation or organization ) 2828 N. Harwood , Suite 1300 Dallas Texas ( Address of principal executive offices ) Title of each class Common Stock $ 0.01 par value ( 214 ) 871-3555 Registrant's telephone number , including area code 75-1056913 ( I.R.S. Employer Identification No. ) Securities registered pursuant to 12 ( b ) of the Securities Exchange Act of 1934 : Trading Symbol ( s ) HFC 75201 ( Zip Code ) For the transition period Name of each exchange on which registered New York Stock Exchange Indicate by check mark if the registrant is a well - known seasoned issuer , as defined in Rule 405 of the Securities Act . 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 . 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 . Yes No ☐ Indicate by check mark whether the registrant has submitted electronically and posted on its corporate web site , if any , 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 ) . 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 . Large accelerated filer Emerging growth company ☑ ☐ Accelerated filer ☐ Non - accelerated filer ☐ Smaller reporting 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 ☑ On June 30 , 2020 , the last business day of the registrant's most recently completed second fiscal quarter , the aggregate market value of the Common Stock , par value $ 0.01 per share , held by non - affiliates of the registrant was approximately $ 4.3 billion , based upon the closing price on the New York Stock Exchange on such date . ( This is not deemed an admission that any person whose shares were not included in the computation of the amount set forth in the preceding sentence necessarily is an " affiliate " of the registrant . ) 162,414,838 shares of Common Stock , par value $ .01 per share , were outstanding on February 16 , 2021 . DOCUMENTS INCORPORATED BY REFERENCE Portions of the registrant's proxy statement for its annual meeting of stockholders to be held on May 12 , 2021 , which proxy statement will be filed with the Securities and Exchange Commission within 120 days after December 31 , 2020 , are incorporated by reference in Part III .