SWX Gas Utilities · Regulated utility · Natural gas · Rate base growth · Thesis updated June 14, 2026

A cleaner utility, with one big build

SWX is now a pure-play regulated gas utility after selling its remaining Centuri shares in September 2025.
The core business serves about 2.3 million customers across Arizona, Nevada, and California.
The Great Basin expansion is the main growth lever, with about $1.7 billion of possible capital investment and a late 2028 target in-service date.
Customer growth slowed to 1.0% for the twelve months ended March 31, 2026, down from 1.6% in the prior period.
The setup is steadier than before, but Finn still flags a price and balance sheet question, with valuation and financial health scores below the overall score.

01 Running thesis

Cleaner story, heavier project risk

Southwest Gas has become a simpler company. It finished the Centuri sale in September 2025, so the story is no longer split between a gas utility and a construction services business. That makes earnings easier to understand and lowers the old breakup risk.

The bull case now rests on regulated utility growth. The Great Basin expansion has become the key prize. The project was helped by an April 2026 binding open season that was significantly oversubscribed, with expressions of incremental interest totaling 2.5 billion cubic feet per day. The company has described about $1.7 billion of possible capital investment and a late 2028 in-service date, subject to FERC approval.

The bear case is that the base business is not growing fast enough to carry the whole story by itself. Customer growth slowed to 1.0% for the twelve months ended March 31, 2026, from 1.6% in the prior period. That puts more pressure on Great Basin to arrive on time and close to budget.

There is also an accounting control issue that has not gone away. Management said disclosure controls were not effective as of March 31, 2026 because of a material weakness first disclosed in the 2025 Form 10-K. Until that is fixed, investors have to treat the reported numbers with extra care.

May 2026→The Great Basin open season was significantly oversubscribed, which strengthened the long-term growth case. At the same time, customer growth slowed to 1.0% and the material weakness in controls remained open.

Feb 2026→The 2025 Form 10-K made Great Basin more concrete, with about $1.7 billion of possible investment and a late 2028 target. The same filing added concerns about internal controls, labor, materials, and slower 1.6% customer growth.

Nov 2025▲SWX completed the sale of its remaining Centuri shares. The company became a pure-play regulated gas utility, shifting the debate toward rate cases and Great Basin execution.

Aug 2025▲Management raised the possible Great Basin capital opportunity to a range of $1.2 billion to $1.6 billion. This gave the market a larger and clearer long-term growth project to judge.

Aug 2025▲The company sold down more of its Centuri stake and reported progress toward full separation. Great Basin also closed a binding open season with potential incremental capacity of up to about 1.76 billion cubic feet per day.

May 2025▲The Q1 2025 call gave more clarity on the path to sell the remaining Centuri stake. Management also pointed to a binding open season for a possible Great Basin expansion.

May 2025▲Arizona regulators approved an annual rate increase of about $80.2 million and a 9.84% return on common equity. That helped support the regulated utility earnings base.

02 Business model

Rates decide most of the money

Southwest Gas buys, distributes, and transports natural gas through Southwest Gas Corporation. It serves residential, commercial, industrial, and other customers in Arizona, Nevada, and California.

This is a regulated utility model. State regulators approve the rates customers pay. In plain English, the company is allowed to earn a set return on approved assets, like pipes and meters. That can make profits steadier than a normal industrial company.

Revenue is largely decoupled from sales volume, which means the company is less exposed to weather or short-term gas usage than a simple volume-based business would be. The tradeoff is regulatory lag. If costs rise before regulators approve higher rates, earnings can get squeezed.

Recent rate cases matter. California rates tied to the 2026 general rate case took effect July 1, 2026 for many settled items, while return on equity and capital structure were still awaiting a CPUC decision. Arizona and Nevada rate cases filed in early 2026 are also important watch points.

03 Product portfolio

One utility, several jobs

Cash cow

Residential gas distribution

This is the everyday home gas service that makes up over 99% of the customer base. It is regulated, steady, and tied to approved utility rates.

Steady

Commercial and industrial service

SWX also serves businesses and industrial users that need natural gas. This is smaller by customer count, but it adds demand across the same gas network.

Steady

Gas transportation

The company moves gas through its system for customers and shippers. These services depend on pipeline capacity and regulatory approvals.

Steady

Pipeline, meters, and maintenance

Southwest Gas invests in pipes, meters, safety work, and system upkeep. Regulators decide how much of that spending can enter rate base and earn a return.

Growth engine

Great Basin expansion

Great Basin is the main long-term growth project. The April 2026 open season was significantly oversubscribed, but the project still needs approvals, labor, materials, and clean execution.

04 Business segments

Geography drives the mix

Arizona natural gas distribution53%modest

Nevada natural gas distribution35%modest

California natural gas distribution12%flat

SWX reports one operating business, Natural Gas Distribution. For the twelve months ended March 31, 2026, operating margin contribution was 53% Arizona, 35% Nevada, and 12% California.

05 Risk factors

What could break the thesis

Great Basin delays or overruns

High impact · Medium odds

The Great Basin expansion is now the biggest growth driver. Management has warned that limited contract labor, steel pipe, compression equipment, rights of way, and construction resources could delay the project or raise its cost. If the project slips past late 2028 or costs much more than planned, the growth case weakens.

We watchFERC application progress, updated capital cost guidance, and any change to the late 2028 in-service target.

Slower customer growth

Medium impact · High odds

Customer growth slowed to 1.0% for the twelve months ended March 31, 2026. That was down from 1.6% in the prior period. If this slowdown continues, SWX has less organic growth and needs more from rate cases and Great Basin.

We watchNet customer growth in each quarterly filing, especially in Arizona and Nevada.

Unfavorable rate case outcomes

High impact · Medium odds

The company depends on regulators in Arizona, Nevada, and California to approve rates that recover costs and allow a fair return. California settled many revenue requirement items, but return on equity and capital structure remained open as of July 2026. Arizona and Nevada cases filed in 2026 are still key earnings events.

We watchFinal CPUC decision on return on equity and capital structure, the Arizona GRC schedule, and the Nevada GRC hearing and order.

Internal control weakness

High impact · Medium odds

SWX disclosed a material weakness in internal control over financial reporting in the 2025 Form 10-K. The weakness still existed as of March 31, 2026, and management said disclosure controls were not effective. This does not prove the numbers are wrong, but it raises the risk of errors or late reporting.

We watchManagement's remediation update and any statement that disclosure controls are effective again.

Inflation and interest cost lag

Medium impact · Medium odds

Utilities often recover higher costs through rates, but not always right away. Higher operating costs and higher interest expense can hurt earnings before regulators approve customer rate increases. This is called regulatory lag.

We watchInterest expense trends, operating expense growth, and allowed rate increases in new orders.

06 Quick answers

In one breath

What does Southwest Gas Holdings do?

Southwest Gas Holdings owns Southwest Gas Corporation, a regulated natural gas utility. It distributes and transports gas for customers in Arizona, Nevada, and California.

Why did the Centuri sale matter for SWX?

Centuri was a utility infrastructure services business, which made SWX harder to value and more exposed to construction market swings. After the September 2025 sale, SWX became a simpler pure-play gas utility.

What is the Great Basin expansion?

Great Basin is a planned pipeline expansion tied to new shipper demand. The company has described about $1.7 billion of possible capital investment and a late 2028 target in-service date, but it still needs approvals and good project execution.

Is SWX a high-growth stock?

Not in the usual sense. It is a regulated utility with steady earnings traits, but customer growth slowed to 1.0% and the largest growth driver is a large project that will take years to build.