Tech Stocks Tumble, Putting Pressure on Broader Market The Nasdaq and the S&P 500 had their worst day since June as investors worried about spending on A.I. infrastructure.

Stock index performance in October A sell-off in artificial intelligence stocks accelerated on Friday, as investors fretted about whether the industry’s debt-fueled spending spree still justified such high share prices.

The tech-heavy Nasdaq Composite index dropped 2.9 percent on the last trading session of the month, while the broader S&P 500 index shed 1.8 percent, the worst one-day showing since June for both.

The makers of computer chips were particularly hard hit. Intel plunged 29.2 percent after the chipmaker reported financial results that fell short of Wall Street’s expectations. The Philadelphia Semiconductor Index, a benchmark for the industry, fell 7.2 percent. The shares of Amazon, Nvidia and other tech giants also fell.

Still, in the face of the tech sell-off, the market as a whole has shown resilience, bolstered by strength in sectors like energy and utilities, and in companies selling everyday goods. Shares of consumer staples companies rose 1.4 percent on Friday; the energy sector rose 1.9 percent.

For some investors, the diverging trajectories have helped allay fears that if the A.I. trade falters, the entire market will fall with it. It points to investor confidence in sectors that have languished for years. And it shows how even as worries about some A.I. companies have intensified, money has not fled the stock market but is instead being redeployed within it.

Even after Friday’s slide, the S&P 500 posted a loss of only 0.9 percent for October, extending a modest 0.5 percent loss in September. The index is not far below its record high, set earlier this month. S&P 500 index How stocks are trading in the United States“Money is sloshing around,” said Chris Galipeau, an economist at the Franklin Templeton Institute, the research arm of the asset manager. “We are still close to the all-time high.”A.I. and technology stocks more broadly have been the backbone of the market rally for years. But investors are increasingly questioning whether the A.I. industry’s lofty valuations are realistic, as worries mount about whether profit growth can keep pace with the expectations embedded in high stock prices.

This month, investors dialed down bets on some A.I. companies, leading to a flurry of sharp, volatile sell-offs. And as companies have reported financial results for the three months through September, investors have looked for more evidence from new, unproven A.I. businesses that their big bets will pay off.

Nasdaq Composite Index How the tech-heavy index in the United States is trading The communication services sector fell 15.2 percent in October, led by losses for technology companies AppLovin and Reddit, and closely followed by Alphabet and Meta, two of the companies at the forefront of the A.I. build-out.

Alphabet this week reported earnings that fell short of investors’ expectations, especially in light of the vast sums it is spending. Google’s parent company suffered its worst day in the stock market on Thursday, with its share price falling 12.6 percent and into negative territory for the year. Alphabet has slid roughly 30 percent since its peak in May, putting the company into a bear market, defined as a loss of 20 percent or more from a recent high. It shed another 1.4 percent on Friday.

Alphabet is one of five “hyperscalers” driving the A.I infrastructure build-out. Two of the others — Oracle and Meta — are also in a bear market. Amazon’s earnings report on Thursday sent its shares falling, leaving it up just 4.1 percent for the year. Microsoft is 7.9 percent higher, close to its high for the year.

“A lot of conversations we’re having with clients is, ‘You’ve done well with A.I. because you were in the market or you were concentrated, but now it’s time to think about rebalancing and putting money elsewhere,’” said Joe Quinlan, head of market strategy for the chief investment office for Merrill and Bank of America Private Bank. Even A.I. companies that are seen as more restrained in their spending, and that surpassed earnings expectations, have struggled.

Microsoft reported earnings that broadly beat investors’ expectations on Wednesday, but the company’s stock price still nudged lower on Thursday after it announced that it would raise a further $25 billion from bond investors.

It fell 1.5 percent on Friday. “The earnings bar is very high,” Mr. Galipeau said. “We have seen what happens when companies don’t hit that bar.”As investors have reduced their growth expectations, Treasury yields, which are sensitive to such expectations, have also fallen. The 10-year Treasury yield dipped back below 5 percent this week, having peaked at 5.3 percent earlier in October.

And that decline in Treasury yields, which represent the base-line government borrowing costs that underpin interest rates for consumers and companies, has helped lift some of the parts of the market that are more sensitive to interest rates.

Overall, nine of the 11 sectors of the S&P 500 have risen in October, with investors pouring roughly $60 billion into funds that buy U.S. stocks, according to data from EPFR Global, a research company.

Energy stocks have led the index higher, lifted by a renewed rise in oil prices that has bolstered the earnings of Exxon, Chevron and other major players in the industry. Brent crude, the international oil benchmark, rose to $117.64 per barrel on Friday, up from just above $102 at the end of September and around $72 just before the war with Iran started at the end of February. The energy sector of the S&P 500 has risen 14 percent this month.

Stocks in utilities and consumer staples, two sectors that are seen as very sensitive to the path of interest rates, have risen more than 10 percent in October. The Russell 2000 index of smaller companies, which fell over 11 percent from mid-August to mid-October, ended the month slightly higher.

Risks remain. The midterm elections on Tuesday and the continuing war with Iran create uncertainty over the month ahead. Investors are also mindful that inflation could accelerate and Treasury yields rise again, reapplying pressure to the parts of the market that have risen this month while potentially slowing the A.I. expansion.

“Investors are essentially reallocating some of that A.I. capital into sectors that are more defensive for now, as they see how the A.I. trade plays out,” said Malik Ahmed Khan, a technology analyst at Morningstar.

Joe Rennison writes about financial markets, a beat that ranges from chronicling the vagaries of the stock market to explaining the often-inscrutable trading decisions of Wall Street insiders.

Aruni Soni is a business reporter and a member of the 2026-27 Times Fellowship, a program for journalists early in their careers.