HF Sinclair Corporation announced the promotion of Tim Go to the position of President of HF Sinclair, effective May 9, 2023. In addition, effective February 16, 2023, the Board of Directors of HF Sinclair increased the size of the Board by one to thirteen, appointed Mr. Go as a non-independent director to the Board and appointed Mr. Go to serve on the Executive Committee of the Board. Mr. Go has served as President and Chief Operating Officer of HF Sinclair since November 2021.

He served as Executive Vice President and Chief Operating Officer of HF Sinclair from June 2020 to November 2021. Prior to joining HF Sinclair, Mr. Go served as Chief Executive Officer of the general partner of Calumet Specialty Products Partners, L.P., an independent producer of specialty hydrocarbon products, from January 2016 to April 2020 and retired from Calumet in June 2020. Prior to joining Calumet, he served in various leadership roles at Koch Industries Inc. and Flint Hills Resources, LP, a wholly-owned subsidiary of Koch Industries Inc. from August 2008 to September 2015, having most recently served as Vice President, Operations of Flint Hills Resources, LP from July 2012 to September 2015.

Prior to joining Koch Industries, he held various roles of increasing responsibility in downstream operations during his 18 years at ExxonMobil Corporation. Mr. Go brings to the Board extensive industry experience and familiarity with the day-to-day operations of HF Sinclair. He provides a significant resource for the Board and facilitates communication between management and the Board.

Mr. Go succeeds Michael C. Jennings, who currently serves as the Chief Executive Officer of HF Sinclair and will continue serving in that role through May 8, 2023. In order to facilitate an orderly transition of the Chief Executive Officer duties from Mr. Jennings to Mr. Go, on February 15, 2023, HF Sinclair announced that Mr. Jennings was appointed to the position of Executive Vice President, Corporate of HF Sinclair, effective May 9, 2023, and is expected to serve in that role through his currently planned retirement date of November 9, 2023. Following his retirement date, Mr. Jennings will provide consulting services to HF Sinclair until February 9, 2024.

Mr. Jennings, who currently serves as a non-independent director on the Board, will not stand for re-election at HF Sinclair's 2023 Annual Meeting of Stockholders, at which time the size of the Board will be decreased by one to twelve. Mr. Jennings continues to serve as Chairperson of the Board of Directors, Chief Executive Officer and President of Holly Logistic Services, L.L.C., the ultimate general partner of Holly Energy Partners, L.P.