Wall Street closed out October's last trading Friday with a brutal day for technology shares. Fresh doubts about whether the huge bets on artificial intelligence will ever pay for themselves pushed investors to dump chipmakers and cloud names in bulk.

The S&P 500 slid 1.8% to finish at 7,580.07. That was the broad index's steepest one-day fall since June and it locked in a third losing week in a row. The tech-heavy Nasdaq composite took the hardest hit with a 2.9% drop to 25,437.00. The Dow gave up 572 points, or 1.1%, to end at 51,770.31.

The Nasdaq-100 lost about 3.4% by itself as more than $1 trillion in market value vanished. That left the index flirting with a correction, the term traders use for a 10% slide from a recent peak. Technology was easily the weakest of the 11 S&P sectors with a loss of more than 4%.

Intel leads the plunge

Intel was the day's biggest casualty. Its shares collapsed roughly 29% after the company gave a sales forecast for the months ahead that fell well short of hopes. Market records going back to the 1980s show no worse single session for the chipmaker.

The pain spread fast across the chip world. AMD, Arm, Qualcomm and Marvell each dropped near 10%. Memory maker SanDisk sank 13% while Micron lost about 5%. Nvidia, the bellwether of the AI trade, shed around 4%. The Philadelphia semiconductor index, a key gauge for the group, tumbled 7.2%.

Companies that rent out AI computing power were punished as well. CoreWeave and Nebius both fell by more than 10%.

Why investors are nervous

The worries built up on Thursday. Amazon told investors it is spending on AI data centers even faster than expected while growth in its online store cooled. Its stock dove in late trading that night but clawed back most of the damage and closed Friday off only 1.4%. Alphabet had already posted its worst session on record a day earlier after its core ad sales came up short.

The biggest tech firms are pouring hundreds of billions of dollars into chips and data centers. Fund managers now want clear proof that the spending turns into profit. Some customers that buy access to AI models have also started trimming what they spend.

Not every corner of the market suffered. Money moved toward steadier names such as Procter & Gamble and Berkshire Hathaway. Even after Friday's slide the S&P 500 sits only about 3% under its all-time high.

Traders will be watching Monday to see whether bargain hunters step in or whether the selling deepens with a busy election week ahead.