Key Highlights

● MasTec, Dycom and Primoris all hit 52-week lows in Thursday's AI power selloff.

● Quanta Services sank to $552.44 and GE Vernova plunged to $827.42.

● Comfort Systems reported earnings of $13.91 a share and a backlog of $17.81 billion.

● Railroads rallied after strong results, with CSX jumping to $51.67.

Engineering and construction stocks tied to the artificial-intelligence power build-out tumbled on Thursday, October 22, with several names sinking to 52-week lows as Wall Street grew nervous about the cost of funding AI infrastructure.

MasTec (NYSE:MTZ), Dycom Industries (NYSE:DY) and Primoris Services (NYSE:PRIM) all hit 52-week lows in what was described as a broad engineering-and-construction and power selloff. Quanta Services (NYSE:PWR) sank to $552.44. The declines came as the S&P 500 fell 93.74 points to 7,663.43, its worst day since July, and the Nasdaq Composite sank 694 points.

From AI winners to AI casualties

Investors have linked these companies to the AI power build-out, which left them exposed when sentiment toward AI spending soured.

The trigger was the report from Meta Platforms (NASDAQ:META) on Wednesday evening. Meta said it expects 2026 capital spending of $135 billion to $145 billion, posted negative free cash flow of $2.12 billion and disclosed about $825 billion in spending commitments. The scale of the outlays raised questions about how such projects will be paid for.

Nvidia (NASDAQ:NVDA) CEO Jensen Huang added to the anxiety. "The demand of the capital is much greater than the availability of the capital," he said. IBM (NYSE:IBM) CEO Arvind Krishna said customers "are also getting worried if some of the AI spending is completely out of control with no real return."

The power trade unwinds

The selling spread across the AI power complex. GE Vernova (NYSE:GEV) plunged to $827.42 and was one of the three worst performers in the S&P 500, selling off on Meta-driven worries about financing for AI data centers ahead of its own third-quarter report.

Vertiv (NYSE:VRT) tumbled on hyperscaler spending fears. Eaton (NYSE:ETN) slid to about $369. Power producer Vistra (NYSE:VST) also sank, while one brokerage trimmed its price target by just $1, to $226, and kept an Overweight rating. Caterpillar (NYSE:CAT) was the worst performer in the Dow Jones Industrial Average.

Comfort Systems slides after hours despite a beat

Comfort Systems USA (NYSE:FIX) fell during the regular session and slid again in after-hours trading on Thursday despite strong third-quarter results.

The company reported earnings of $13.91 a share, up from $8.25 a year earlier, on revenue of $3.77 billion, compared with a $3.39 billion figure in market data. Its backlog grew to $17.81 billion from $14.06 billion at the end of June. Bloom Energy (NYSE:BE) also fell after hours despite beating estimates and raising its 2026 outlook.

Money moved elsewhere

Investors did not abandon industrial stocks entirely. Railroads rallied after strong results, with CSX (NASDAQ:CSX) jumping to $51.67 and Union Pacific (NYSE:UNP) climbing. Lockheed Martin (NYSE:LMT) jumped after beating estimates and raising its full-year profit outlook. United Rentals (NYSE:URI) reported adjusted EBITDA of $2.33 billion, beating estimates, and raised its guidance.

Overall, the industrials sector edged lower, while staples, health care and utilities led the market.

GE Vernova and Big Tech Spending on Deck

GE Vernova's upcoming third-quarter report will be closely watched for its view on data-center power demand. Caterpillar reports on October 29, the same day as Amazon (NASDAQ:AMZN).

Microsoft (NASDAQ:MSFT) and Alphabet (NASDAQ:GOOGL) report on October 28. Their capital spending plans will shape sentiment toward the companies that build AI's physical infrastructure. Any sign that spending growth is slowing could weigh further on the group.