Results of Operations and Financial Condition. On August 5, 2026, Southwest Gas Holdings, Inc. released summary financial information to the general public, including the investment community, regarding operating performance for the quarter and six months ended June 30, 2026. A copy of the associated press release and summary financial information is attached hereto as Exhibit 99. This Form 8-K and the attached exhibit are provided under

Results of Operations and Financial Condition. On May 5, 2026, Southwest Gas Holdings, Inc. released summary financial information to the general public, including the investment community, regarding operating performance for the quarter ended March 31, 2026. A copy of the associated press release and summary financial information is attached hereto as Exhibit 99. This Form 8-K and the attached exhibit are provided under

Results of Operations and Financial Condition. On February 25, 2026 , Southwest Gas Holdings, Inc. released summary financial information to the general public, including the investment community, regarding operating performance for the quarter and twelve months ended December 31, 2025 . A copy of the associated press release and summary financial information is attached hereto as Exhibit 99. This Form 8-K and the attached exhibit are provided under

President, Chief Executive Officer and Director — Karen S. Haller: Karen S. Haller is resigning as President, CEO, and Director with a named successor.

Termination of a Material Definitive Agreement. On February 11, 2026, Southwest Gas Holdings, Inc. (the “Company”) and Carl C. Icahn and the persons and entities listed in the Cooperation Agreement (as defined below) (collectively, the “Icahn Group” and together with the Company, the “Parties”) mutually agreed to terminate that certain Amended and Restated Cooperation Agreement, dated as of October 14, 2025, by and between the Parties (the “Cooperation Agreement”). As a result of such termina…

Director — Anne L. Mariucci: Ms. Mariucci will not stand for re-election and will retire from the Board at the conclusion of the 2026 Annual Meeting.

and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing made by the Company under the Exchange Act or the Securities Act of 1933, as amended (the “Securities Act”), except as shall be expressly set forth by specific reference in such a filing. 1 Southwest Gas 2025-2029 guidance CAGRs do not include…

of this Current Report on Form 8-K shall not be deemed “filed” for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference into any filing made by the Company under the Exchange Act or the Securities Act, except as shall be expressly set forth by specific reference in such a filing. Non-GAAP Measures To supplement our financial statements, which are presented on the basis of GAAP, the following non-G…

Non-Reliance on Previously Issued Financial Statements or a Related Audit Report or Completed Interim Review On January 9, 2026, the Audit Committee, following consultation with the Company's management and PricewaterhouseCoopers LLP, the Company's independent registered public accounting firm, concluded that the Company’s unaudited Condensed Consolidated Financial Statements for the Restated Periods, previously reported in its Quarterly Reports on Form 10-Q for the three and six months ended…

Director — Andrew Teno: A designated director resigned as part of a negotiated cooperation agreement with the Icahn Group, resulting in a planned reduction of board size rather than a sudden loss of a senior executive.

CFO — Justin S. Forsberg: The filing discloses the internal promotion of a long-serving executive to the CFO role, which is a standard succession event rather than a departure.

Other Events Concurrently with this Current Report on Form 8-K, the Company is filing a prospectus supplement (the “Resale Prospectus Supplement”) to the prospectus contained in its effective Registration Statement on Form S-3ASR (File No. 333-275774) to register the resale, from time to time, of shares of the Company’s common stock, par value $1.00 per share, held by the selling stockholders named therein (the “Shares”), pursuant to the Registration Rights Agreement. The Company will not rec…

Entry into a Material Definitive Agreement In accordance with that certain Amended and Restated Cooperation Agreement, dated October 14, 2025 (the “Cooperation Agreement”), Southwest Gas Holdings, Inc. (the “Company”) and Carl C. Icahn and the persons and entities listed therein (collectively, the “Icahn Group”) entered into a registration right s agreement on November 26, 2025 (the “Registration Rights Agreement”). Pursuant to the Registration Rights Agreement, among other things, and subjec…

CFO — Robert J. Stefani: The CFO is departing to pursue new opportunities with a negotiated separation agreement and no reported disagreements, indicating an orderly executive exit rather than a forced termination or routine board change.

Results of Operations and Financial Condition. On November 5, 2025, Southwest Gas Holdings, Inc. released summary financial information to the general public, including the investment community, regarding operating performance for the quarter and nine months ended September 30, 2025. A copy of the associated press release and summary financial information is attached hereto as Exhibit 99. This Form 8-K and the attached exhibit are provided under

Entry Into a Material Definitive Agreement. On October 14, 2025, Southwest Gas Holdings, Inc. (the “Company”) and Carl C. Icahn and the persons and entities listed therein (collectively, the “Icahn Group” and together with the Company, the “Parties”) entered into an Amended and Restated Cooperation Agreement (the “Amended Agreement”), which amends, restates, supersedes and replaces in its entirety that certain Amended and Restated Cooperation Agreement, dated as of October 15, 2024, by and be…

Other Events On September 3, 2025, Southwest Gas Holdings, Inc. (the “Company”) entered into an underwriting agreement with J.P. Morgan Securities LLC (the “Underwriter”) and Centuri Holdings, Inc. (“Centuri”), pursuant to which the Company agreed to sell 27,362,210 shares (the “Shares”) of its holdings of common stock of Centuri, par value $0.01 per share (“Centuri Common Stock”), to the Underwriter (the “Offering”). The price to the public in the Offering was $19.60 per share. The Offering…

Entry Into a Material Definitive Agreement. Underwritten Offering On August 7, 2025, Southwest Gas Holdings, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with J.P. Morgan Securities LLC, as representative (the “Representative”) of the several underwriters named therein (collectively, the “Underwriters”) and Centuri Holdings, Inc. (“Centuri”), pursuant to which the Company agreed to sell 15,000,000 shares (the “Initial Shares”) of its holdings of c…

Completion of Acquisition or Disposition of Assets. Reference is made to the information disclosed under

Results of Operations and Financial Condition. On August 6, 2025, Southwest Gas Holdings, Inc. released summary financial information to the general public, including the investment community, regarding operating performance for the quarter and six months ended June 30, 2025. A copy of the associated press release and summary financial information is attached hereto as Exhibit 99. This Form 8-K and the attached exhibit are provided under

Chief Accounting Officer — Fabio A. Pineda: The filing announces the external hire of a new Chief Accounting Officer and Controller, noting that the outgoing Controller is transitioning to a different role rather than leaving the company.

Other Events. On July 8, 2025, Southwest Gas Holdings, Inc. (the “Company”) closed the previously announced sale of an aggregate of 1,060,240 shares of its holdings of common stock of Centuri Holdings, Inc. (“Centuri”), par value $0.01 per share (the “Centuri Common Stock”) to Icahn Partners LP and Icahn Partners Master Fund LP, investment entities affiliated with Carl C. Icahn (collectively, the “Icahn Investors”), at $20.75 per share, pursuant to that certain Common Stock Purchase Agreement…

Creation of a Direct Financial Obligation or an Obligation under an Off-Balance Sheet Arrangement of a Registrant. The disclosure set forth under

Entry Into a Material Definitive Agreement. Second Amended and Restated Term Loan Agreement On June 27, 2025, Southwest Gas Holdings, Inc. (the “Company”) entered into a Second Amended and Restated Term Loan Credit Agreement (the “Amended Term Loan Agreement”) with the lenders party thereto, JPMorgan Chase Bank, N.A. as Administrative Agent, Bank of America, N.A. as Syndication Agent, JPMorgan Chase Bank, N.A., BofA Securities, Inc., Wells Fargo Securities, LLC and U.S. Bank National Associat…

Entry Into a Material Definitive Agreement. Amendment to Southwest Gas Corporation Revolving Credit Agreement On June 27, 2025, Southwest Gas Corporation entered into the First Amendment to Credit Agreement (the “First Amendment”) to its Revolving Credit Agreement, dated as of August 1, 2024, with the lenders party thereto, and Bank of America, N.A., as Administrative Agent and Swingline Lender. The First Amendment, among other things, added a swingline sub-facility and added a one-week inter…