SCHEDULE 13D/A

SOUTHWEST GAS CORP

Common Stock, Par Value $1.00 per share · CUSIP: 844895102

Event date: 2026-01-27

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• Icahn Partners Master Fund LPReported CIK 0001322827

  Shares: 1,559,508.00 · Class: 2.16%

• Icahn Offshore LPReported CIK 0001322825

  Shares: 1,559,508.00 · Class: 2.16%

• Icahn Partners LPReported CIK 0001313666

  Shares: 2,040,492.00 · Class: 2.83%

• Icahn Onshore LPReported CIK 0001322826

  Shares: 2,040,492.00 · Class: 2.83%

• Icahn Capital LPReported CIK 0001412093

  Shares: 3,600,000.00 · Class: 4.99%

• IPH GP LLCReported CIK 0001412091

  Shares: 3,600,000.00 · Class: 4.99%

• Icahn Enterprises Holdings L.P.Reported CIK 0001034563

  Shares: 3,600,000.00 · Class: 4.99%

• Icahn Enterprises G.P. Inc.Reported CIK 0001257324

  Shares: 3,600,000.00 · Class: 4.99%

• Beckton Corp.Reported CIK 0001080113

  Shares: 3,600,000.00 · Class: 4.99%

• IEP Utility Holdings LLCReported CIK 0001889149

  Shares: 0.00 · Class: 0%

• Carl C. IcahnReported CIK 0000921669

  Shares: 3,600,000.00 · Class: 4.99%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.