Form SCHEDULE 13D/A HF Sinclair Corp Filed by: REH Advisors Inc.

The information contained in the explanatory note and Items 3 and 6 of the Schedule 13D is incorporated herein by reference. On May 18, 2026, the Issuer entered into a Stock Purchase Agreement (the "Twenty-First Purchase Agreement") with the Reporting Person to repurchase 1,455,180 shares of Common Stock, for $68.72 per share, for the aggregate purchase price of $99,999,970 in a privately negotiated transaction (the "Twenty-Second Repurchase Transaction"). The Twenty-Second Repurchase Transaction is expected to close on or about May 21, 2026, subject to customary closing conditions. The foregoing description of the Twenty-First Purchase Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Twenty-First Purchase Agreement, which is filed as Exhibit 10.23 hereto and is incorporated herein by reference. As previously reported, the Reporting Person has sold its Common Stock from time to time in both open market sales and sales to the Issuer. Subject to the terms of the Stockholders Agreement, the Reporting Person expects to continue to engage in such sales (with a strong preference for sales to the Issuer), but the Reporting Person may both acquire additional Common Stock or dispose of any or all of the Common Stock, in each case, depending upon an ongoing evaluation of the investment in the Common Stock, prevailing market conditions, other investment opportunities, other investment considerations and/or other factors. The Reporting Person evaluates its investments in the Common Stock on a continual basis. Additionally, while the Reporting Person reserves the right to make sales from time to time, it is its intent as of the date of this Amendment to maintain such sufficient ownership of Common Stock so the Reporting Person retains the right to appoint at least one director to the Board of the Issuer pursuant to the Stockholders Agreement. The Reporting Person may, at any time and from time to time, review or reconsider such position.

(a.) - (b.) The aggregate number and percentage of Common Stock beneficially owned by the Reporting Person (on the basis of a total of 180,275,437 shares of Common Stock outstanding as of April 27, 2026, as reported in the Issuer's Quarterly Report on Form 10-Q, filed with the SEC on May 1, 2026, less the Common Stock acquired by the Issuer pursuant to the Twenty-Second Repurchase Transaction) are as follows: A. REH Advisors Inc. i. Amount beneficially owned: 11,256,662 Percentage: 6.3% a. Sole power to vote or to direct the vote: 0 b. Shared power to vote or to direct the vote: 11,256,662 c. Sole power to dispose or to direct the disposition of: 0 d. Shared power to dispose or to direct the disposition of: 11,256,662

To the best knowledge of the Reporting Person, no transactions were effected by the Reporting Person during the past 60 days other than the transactions described herein.

No other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, any of the Common Stock beneficially owned by the Reporting Person, other than as described herein.

Not applicable.

The information contained in the explanatory note and Items 3 and 4 of the Schedule 13D is incorporated herein by reference.

Exhibit 10.23 Stock Purchase Agreement, dated as of May 18, 2026, by and among HF Sinclair Corporation and REH Advisors Inc. (incorporated by reference to Exhibit 10.1 to the Issuer's Current Report on Form 8-K (File No. 001-41325) filed on May 19, 2026).