The S&P 500 had its best day since April as AMD jumped 13% and chip stocks roared back, even as Nvidia slid to a seven-month low

Wall Street spent Monday undoing a large part of last week's damage. The stocks that were sold hardest after the midterm elections, chipmakers and the companies building out artificial intelligence infrastructure, led a broad rally that lifted every sector of the S&P 500. A sharp drop in oil prices helped, by easing some of the inflation worry that has hung over markets ahead of Tuesday's consumer price report. The one big name left behind was the most important chip stock of all.

How the session ended

The S&P 500 rose 173.08 points, or 2.35%, to 7,549.94, Reuters reported, as carried by The Business Times, matching Yahoo Finance data. It was the index's biggest daily percentage gain since April 8, and AP described it as the market's best day since April. The Dow Jones Industrial Average gained 1,104.02 points, or 2.15%, to 52,389.75. The Nasdaq Composite rose 673.71 points, or 2.74%, to 25,253.14, its largest one-day gain since July 30, according to Dow Jones Market Data.

The rally was broad. All 11 major S&P 500 sector indexes rose, nine of them by more than 1%, with industrials and consumer discretionary leading at more than 3% each, Reuters reported. The Cboe Volatility Index, Wall Street's fear gauge, fell 22.31% to 19.92, according to Yahoo Finance data, back below 20 after last week's spike.

The Nasdaq is not all the way back. Dow Jones Market Data shows the index still 8.50% below its record close of 27,599.79 on Oct. 6, and down 0.72% for the month so far.

The chip rebound

AMD led the semiconductor rally, rising 13.26% to $508.58, according to Yahoo Finance data. Oppenheimer upgraded the stock to outperform on Monday, with analyst Rick Schafer citing strong momentum in its data center business, Investing.com reported. AMD Chief Executive Lisa Su has pushed back against concerns that AI chip demand could weaken, saying demand is exceeding supply, The Economic Times reported.

Others followed. Broadcom rose 8.78% to $319.48 and Micron Technology 6.25% to $733.15, according to Yahoo Finance data. Barchart reported that Applied Materials gained more than 11%, and Lam Research and Seagate Technology more than 10%, while the iShares Semiconductor ETF rose more than 6%. Optical networking company Coherent climbed 16.79% to $225.19, Yahoo Finance data show, one of several AI infrastructure suppliers that CNBC said rebounded after last week's selling.

Nvidia goes the other way

Nvidia fell 4.27% to $178.67, according to Yahoo Finance data, its lowest close since April 7, Reuters reported. The shares were down as much as 8.8% early in the session before recovering part of the loss, according to AFP-Yonhap. The drop came after Nvidia's board said on Sunday that a committee of independent directors would investigate reports that Huang had been the target of a foreign intelligence effort.

The investigation follows a New York Times report that Huang had a close relationship with a businesswoman whom U.S. intelligence officials believe passed information to the Chinese government. Huang has acknowledged an affair and apologized, the BBC reported. Nvidia has said it has no reason to believe that national security or company secrets were compromised, and China's government has called the claims a smear. President Trump said Huang is "a fine person, but you never know what's going on," according to the BBC.

"I'm pushing to investigate Jensen Huang and Nvidia to determine whether our national security was compromised." - Sen. Chris Coons, a Delaware Democrat, in a post on X, as quoted by Reuters

Megacaps, airlines and oil

The rest of the largest technology companies rallied. Tesla rose 5.54% to $378.05, according to Yahoo Finance data, and Barchart said Meta Platforms also gained more than 5%, with Amazon and Microsoft up more than 3%. Airline stocks climbed as fuel costs fell: United Airlines rose 6.78% to $120.38, Yahoo Finance data show.

Oil was a big part of the story. U.S. crude for December delivery fell $3.98, or 4.38%, to settle at $86.85 a barrel, Xinhua reported, after President Trump played down the likelihood of renewed strikes on Iran. That compares with Friday's settlement of $90.83. Gold moved the other way: December futures settled 1% higher at $4,114.50 an ounce, CNBC reported.

What carries into Tuesday

The next test arrives before the opening bell. The October consumer price index is due at 8:30 a.m. ET on Tuesday, and economists polled by Dow Jones expect a 0.3% monthly rise in headline prices and 0.2% in core prices, CNBC reported. After Friday's strong jobs report, investors will be watching whether inflation gives the Federal Reserve more reason to raise rates in December.

"With inflation elevated and the economy on solid footing, we expect the Federal Reserve to remain focused on the inflation side of its dual mandate and to deliver another 0.25-percentage-point interest-rate increase in December." - Brock Weimer, investment strategy analyst at Edward Jones, as quoted by CNBC

Treasury yields edged up ahead of the data. The 10-year yield ended at 4.88%, up from 4.86% on Friday, and the 2-year yield rose to 4.56% from 4.51%, according to the Treasury Department's daily rates. Investors will also be watching for more news from Nvidia's board, and whether Monday's rebound in the rest of the chip sector can hold if the leader of the AI trade stays under pressure.