Oil prices eased on Monday, helping to calm Wall Street's concerns that inflation could worsen further. The decline fueled a rally across U.S. stock indexes, though sharp swings continued to roil markets beneath the surface.

The S&P 500 rose 1.5 percent, recovering from a volatile July in which it swung up and down as oil prices shot higher due to the war with Iran and other mounting worries. The Dow Jones Industrial Average climbed 591 points, or 1.1 percent, as of 1:57 p.m. Eastern time, and the Nasdaq composite gained 2.2 percent.

Stocks received a lift as the price of a barrel of Brent crude sank 5 percent to $83.49. The drop came after President Donald Trump said over the weekend that he had decided to hold off on new strikes against Iran at the urging of allies in the region.

Brent's price had careened between $72 and $102 last month as worries fluctuated over when the war with Iran would allow oil tankers to freely exit the Persian Gulf again and deliver crude to customers worldwide. The Persian Gulf includes the Strait of Hormuz, through which roughly a fifth of the world's daily oil supply routinely passes. Trump's latest decision on Iran helped ease concerns about the global flow of crude, and Treasury yields fell correspondingly in the bond market.

The yield on the 10-year Treasury sank to 4.69 percent from 4.75 percent late Friday. It remains well above its 3.97 percent level from before the war with Iran, however. Higher yields threaten to undercut prices for stocks and other investments while slowing the economy by making borrowing more expensive for U.S. households and businesses. The average long-term U.S. mortgage rate has already jumped to its highest level in a year. The Federal Reserve has been watching oil-driven inflation closely as it weighs whether to continue holding its benchmark interest rate at its highest level in over two decades.

Monday's decline in oil prices helped airlines and other companies with substantial fuel costs lead the market. United Airlines surged 5.2 percent, American Airlines climbed 4.2 percent, and Norwegian Cruise Line Holdings advanced 3.9 percent.

Tyson Foods rose 2 percent after the meat company reported a slightly stronger profit for the spring than analysts had expected. CEO Donnie King said strength is continuing in the company's chicken business and its prepared foods segment, which includes brands such as Jimmy Dean and Hillshire Farm.

Tyson joined a lengthening list of major U.S. companies to deliver a bigger profit for the spring than analysts anticipated. That is imperative for Wall Street because stock prices tend to follow the trajectory of corporate earnings over the long term, and worries had been intensifying that stock prices may have already risen too far, too fast.

Companies in the S&P 500 are on track to deliver earnings per share for the spring that are 47 percent higher than a year earlier, according to FactSet, with more than half of the companies having already reported. If that holds, it would represent the strongest growth since the spring of 2021, when the economy was roaring out of the COVID-19 pandemic.

Also offering encouragement for the profit outlook was a report on Monday showing that U.S. manufacturing growth accelerated to its strongest level since 2022.

Still keeping Wall Street unsettled were swings in the stocks of computer chip manufacturers. They have been veering up and down for weeks on concerns about whether their surging revenues from the artificial intelligence boom are sustainable. Because a handful of large technology and semiconductor companies account for a disproportionate share of major U.S. index returns, their volatility has outsized influence on the broader market. If AI ultimately produces less profit and productivity than hoped, Big Tech companies could curtail their spending sprees on data centers that have driven chip stocks to extraordinary heights.

Micron Technology, for example, swung from a 6.4 percent decline to a 0.7 percent gain during Monday's first 90 minutes of trading. The stock remains up roughly 190 percent for the year so far.

The manic swings for AI stocks have been most dramatic in South Korea, where the Kospi index is dominated by just two technology titans: Samsung Electronics and SK Hynix. Seoul's Kospi fell 5.1 percent on Monday, coming off Friday's 17.9 percent surge — its best day in history.

In neighboring Japan, Tokyo's Nikkei 225 fell 0.9 percent after the United States and Japan confirmed they had moved together to prop up the value of the Japanese yen against the dollar. A stronger yen would help limit inflation in Japan, but it could also potentially hurt the country's exporters.

In Germany, Trump's announcement that there would be new talks with Iran drove the DAX to an all-time high on Monday, surpassing the previous record set in July.