Material Event (Form 8-K)

Item 8.01 Other Events.

As previously announced, on November 2, 2025, SM Energy Company, a Delaware corporation ("SM Energy" or the "Company"), Cars Merger Sub, Inc., a Delaware corporation and direct wholly owned subsidiary of the Company ("Merger Sub"), and Civitas Resources, Inc., a Delaware corporation ("Civitas"), entered into an Agreement and Plan of Merger pursuant to which (i) Merger Sub will merge with and into Civitas, with Civitas surviving as a wholly owned subsidiary of the Company (the "First Company Merger"), and (ii) immediately following the First Company Merger, Civitas as the surviving corporation will merge with and into the Company, with the Company continuing as the surviving corporation (the "Second Company Merger" and, together with the First Company Merger, the "Mergers").

On December 5, 2025, the Company filed with the U.S. Securities and Exchange Commission (the "SEC") a Registration Statement on Form S-4 (Registration No. 333-291956) (the "Registration Statement"), which was declared effective by the SEC on December 19, 2025, and which included a joint proxy statement/prospectus of the Company and Civitas in connection with the Mergers (such joint proxy statement/prospectus as filed by the Company on December 22, 2025, the "Joint Proxy Statement/Prospectus").

Stockholder Communications Related to the Mergers

Since the filing of the Joint Proxy Statement/Prospectus, as of the date hereof, the Company has received multiple demand letters from purported stockholders of the Company (the "Demand Letters") alleging that the Joint Proxy Statement/Prospectus contains certain disclosure deficiencies and/or incomplete information regarding the Mergers. It is possible that additional, similar demand letters may be received by the Company regarding the Mergers or that complaints may be filed against the Company or the Company's board of directors. Absent new or different allegations that are material or a disclosure obligation under the U.S. federal securities laws, the Company will not necessarily disclose such additional demands or complaints.

The Company and the Company's directors deny that any further disclosure beyond that already contained in the Joint Proxy Statement/Prospectus is required under applicable law. However, in order to avoid the risk that the Demand Letters may delay or otherwise adversely affect the consummation of the Mergers, to avoid nuisance and minimize the distractions, uncertainties and expense inherent in litigation, and without admitting any liability or wrongdoing, the Company is voluntarily making certain disclosures below that supplement those contained in the Joint Proxy Statement/Prospectus. These disclosures, and disclosures of certain other matters, are provided in this Current Report on Form 8-K. Nothing in this Current Report on Form 8-K shall be deemed an admission of the legal necessity or materiality under applicable laws of any of the disclosures set forth herein. To the contrary, the Company and the Company's directors specifically deny all allegations in the Demand Letters and specifically deny that any additional disclosure was or is required and that the supplemental disclosures below are otherwise material.

SUPPLEMENT TO PROXY STATEMENT

The Company is supplementing the Joint Proxy Statement/Prospectus with certain additional information set forth below. These disclosures should be read in connection with the Joint Proxy Statement/Prospectus, which should be read in its entirety and is available on the SEC's website at https://www.sec.gov, along with the periodic reports and other information the Company files with the SEC. The supplemental disclosures contained herein will not affect the timing of special meetings of the Company's and Civitas' stockholders, which are scheduled to be held on January 27, 2026, at 10:00 a.m. Mountain Time.

All page references are to pages in the Joint Proxy Statement/Prospectus, and terms used below, unless otherwise defined, have the meanings set forth in the Joint Proxy Statement/Prospectus. To the extent the following information differs from or conflicts with the information contained in the Joint Proxy Statement/Prospectus, the information set forth below shall be deemed to supersede the respective information in the Joint Proxy Statement/Prospectus. New text within the amended and supplemented language from the Joint Proxy Statement/Prospectus is indicated in bold and underlined text (e.g., bold, underlined text), and deleted text within the amended and supplemented language from the Joint Proxy Statement/Prospectus is indicated in bold and strikethrough text (e.g., bold, strikethrough text).