SCHEDULE 13D/A 0001539497-26-000002 0000921669 XXXXXXXX LIVE 16 Common Stock, Par Value $1.00 per share 01/16/2026 false 0001692115 844895102 Southwest Gas Holdings, Inc.

C/O SOUTHWEST GAS CORPORATION 8360 S. DURANGO DRIVE LAS VEGAS NV 89113

Jesse A. Lynn COO (305) 422-4100 Icahn Capital LP 16690 Collins Avenue, PH-1 Sunny Isles Beach FL 33160 0001322827 N Icahn Partners Master Fund LP WC N DE 2062604.00 2062604.00 2062604.00 2062604.00 2062604.00 N 2.86 PN 0001322825 N Icahn Offshore LP OO N DE 0.00 2062604.00 0.00 2062604.00 2062604.00 N 2.86 PN 0001313666 N Icahn Partners LP WC N DE 2698753.00 2698753.00 2698753.00 2698753.00 2698753.00 N 3.74 PN 0001322826 N Icahn Onshore LP OO N DE 0.00 2698753.00 0.00 2698753.00 2698753.00 N 3.74 PN 0001412093 N Icahn Capital LP OO N DE 0.00 4761357.00 0.00 4761357.00 4761357.00 N 6.6 PN 0001412091 N IPH GP LLC OO N DE 0.00 4761357.00 0.00 4761357.00 4761357.00 N 6.6 OO 0001034563 N Icahn Enterprises Holdings L.P. OO N DE 0.00 4761357.00 0.00 4761357.00 4761357.00 N 6.6 PN 0001257324 N Icahn Enterprises G.P. Inc. OO N DE 0.00 4761357.00 0.00 4761357.00 4761357.00 N 6.6 CO 0001080113 N Beckton Corp. OO N DE 0.00 4761357.00 0.00 4761357.00 4761357.00 N 6.6 CO 0001889149 N IEP Utility Holdings LLC OO N DE 0.00 0.00 0.00 0.00 0.00 N 0 OO 0000921669 N Carl C. Icahn OO N X1 0.00 4761357.00 0.00 4761357.00 4761357.00 N 6.6 IN Common Stock, Par Value $1.00 per share Southwest Gas Holdings, Inc. C/O SOUTHWEST GAS CORPORATION 8360 S. DURANGO DRIVE LAS VEGAS NV 89113 Note to Item 1. This statement constitutes Amendment No. 16 to the Schedule 13D (as amended, the "Schedule 13D") relating to the shares of the common stock, par value $1.00 per share (the "Common Stock"), of Southwest Gas Holdings, Inc., a Delaware corporation (the "Issuer"), and hereby amends the Schedule 13D originally filed with the Securities and Exchange Commission (the "SEC") on June 3, 2022. All capitalized terms contained herein but not otherwise defined shall have the meanings ascribed to such terms in the Schedule 13D. As of the date hereof, the Reporting Persons may be deemed to beneficially own, in the aggregate, 4,761,357 shares of Common Stock, representing approximately 6.6% of the Issuer's outstanding shares of Common Stock, based on 72,183,903 shares of Common Stock outstanding as of November 21, 2025, as disclosed by the Issuer in its prospectus supplement filed with the SEC on November 26, 2025. Icahn Master has sole voting and sole dispositive power with respect to 2,062,604 shares of Common Stock. Each of Icahn Offshore, Icahn Capital, IPH GP, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn, by virtue of their relationships to Icahn Master, has shared voting power and shared dispositive power with respect to such shares. Icahn Partners has sole voting and sole dispositive power with respect to 2,698,753 shares of Common Stock. Each of Icahn Onshore, Icahn Capital, IPH GP, Icahn Enterprises Holdings, Icahn Enterprises GP, Beckton and Mr. Icahn, by virtue of their relationships to Icahn Partners, has shared voting power and shared dispositive power with respect to such shares. IEP Utility has sole voting power and sole dispositive power and shared and shared dispositive power with respect to 0 shares of Common Stock; however, IEP Utility has been included in this Schedule 13D as it is a signatory to the 2025 Agreement. Exhibit 1 attached hereto sets forth all transactions with respect to the Shares by any Reporting Person since January 2, 2025 (the date on which the last amendment to this Schedule 13D was filed with the SEC). Except as set forth Exhibit 1, no transactions in the shares of Common Stock were effected by any of the Reporting Persons during such period. Not applicable. Not applicable. 1. Transactions in Shares Icahn Partners Master Fund LP /s/ Jesse Lynn 01/21/2026 Icahn Offshore LP /s/ Jesse Lynn 01/21/2026 Icahn Partners LP /s/ Jesse Lynn 01/21/2026 Icahn Onshore LP /s/ Jesse Lynn 01/21/2026 Icahn Capital LP /s/ Jesse Lynn 01/21/2026 IPH GP LLC /s/ Ted Papapostolou 01/21/2026 Icahn Enterprises Holdings L.P. /s/ Ted Papapostolou 01/21/2026 Icahn Enterprises G.P. Inc. /s/ Ted Papapostolou 01/21/2026 Beckton Corp. /s/ Ted Papapostolou 01/21/2026 IEP Utility Holdings LLC /s/ Ted Papapostolou 01/21/2026 Carl C. Icahn /s/ Carl C. Icahn 01/21/2026