Wall Street’s enthusiasm for artificial intelligence has given way to doubts about the infrastructure needed to sustain it. Stocks plunged this week as investors weighed potential restrictions on data centers alongside disappointing corporate results.

The S&P 500 fell 4.4%, its sharpest daily decline since April 2025. The Dow Jones Industrial Average lost 1,833 points, or 3.4%, while the Nasdaq Composite dropped 5.5%, leaving it more than 10% below its recent peak. Chipmakers bore heavy losses, with Nvidia declining 9.3% and Advanced Micro Devices sinking 17.3%. Power equipment supplier GE Vernova fell 7.5%, illustrating how quickly concerns about AI spending reached beyond technology companies.

The retreat erased a rally following Democrats’ congressional victories. Investors subsequently focused on whether election results and local opposition could obstruct data center construction. A UBS analysis estimated that potential construction pauses could disrupt roughly 30% of projected American capacity additions in 2028.

Weak smartphone chip sales at Qualcomm and a disappointing outlook from Arm compounded the pressure. Still, despite the rout, all three major indexes remained higher for 2026.

The AI boom has inexorably tied expectations for future corporate profits to an enormous program of physical construction. Investors buying chipmakers are also betting that developers can secure land, electricity, water, and permission to build. A bottleneck in any one of these areas undermines demand across the supply chain…

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This makes the political reaction much more consequential than other disputes over tech regulations. Communities are facing immediate high costs from projects whose purported economic benefits may arrive later or accrue elsewhere. Ignoring concerns about utility bills and water supplies could strengthen opposition enough to delay otherwise viable investment.

Republicans can blame Democratic victories for the reversal, but the market rallied after those same results before falling. Disappointing earnings and doubts about valuations complicate any claim that one party caused the losses. The economic risk is that delayed projects prompt suppliers to trim orders, hiring, and expansion.

Construction workers and equipment manufacturers would then absorb consequences originating in technology companies’ investment plans. This most recent decline, while notable, does not establish that such a contraction has begun. Rather, it reveals how much confidence rests on an expansion that still requires public consent.

Millions of Americans have a financial stake in AI through their retirement accounts. Technology giants helped lift S&P 500 index funds, and doubts about their prospects can pull those same funds down. Thursday showed how quickly confidence in future profits can evaporate.

The deeper concern is whether AI investment has made the economy look stronger than its foundations warrant. If companies scale back before other sources of growth emerge, households could face weaker hiring and spending alongside falling portfolio values. AI may yet justify the money committed to it, but a technology can transform an economy without rewarding every company financing its expansion.

Americans’ savings now depend partly on how much of that promised prosperity has been priced in before it has actually been earned by the businesses involved.