U.S. equities opened mixed Thursday after Oracle Corp.’s latest results injected fresh doubt into the near-term payoff from massive artificial intelligence investments, pressuring the tech complex even as the broader market held up.

The S&P 500 slipped 0.4% at the open, edging back from record territory reached earlier in the week. The Nasdaq 100 fell 0.7% as megacap tech names retreated. The Dow Jones Industrial Average bucked the trend, rising about 193 points, or 0.4%.

Sentiment had been buoyant Wednesday after the Federal Reserve signaled a more constructive economic outlook and reinforced expectations for lower interest rates. That optimism faded after Oracle reported quarterly revenue of $16.1 billion, missing analysts’ forecasts, and sharply raised its full-year capital-expenditure outlook to $50 billion from $35 billion.

The disappointment spilled beyond Oracle. Investors have grown increasingly uneasy about the sheer scale of spending required to support AI infrastructure. Deutsche Bank estimates that capital expenditures by hyperscalers—including Amazon, Alphabet and Meta—could reach $500 billion by 2026 and swell to $4 trillion by 2030.

Those investments face a critical bottleneck: power supply. Electricity availability is emerging as one of the biggest constraints on AI monetization, Deutsche Bank said in a presentation Thursday, noting that U.S. households are already paying record electricity prices and that expanding generation and grid capacity will take years.

The market’s pullback underscores a dilemma for tech investors—AI demand is booming, but the cost and complexity of building out the ecosystem needed to support it are rising even faster.