NEW YORK (Reuters) -The three major U.S. stock indexes ended higher on Monday, with Apple giving the S&P 500 a strong boost as the White House exempted smartphones and computers from new tariffs.

Uncertainty over future tariffs kept investors cautious, however, as investors remain worried about how companies will manage supply chains as more developments are expected on the tariff front.

The United States unveiled the exemptions on Friday, but President Donald Trump on Sunday said he would be announcing the tariff rate on imported semiconductors over the next week.

Global technology shares mostly rose on the news, especially for companies that rely on imports from China. Shares of iPhone maker Apple ended higher.

Monday's trading was choppy as it has been since Trump announced sweeping tariffs on April 2. Investors have seen some of the biggest swings in indexes in years amid worries that a global trade war will push the economy into recession.

"Really what we have is just continued uncertainty and inability for consumers and businesses and investors to plan much going forward or have reason to commit to long-term spending plans," said Jed Ellerbroek, a portfolio manager at Argent Capital Advisors in St. Louis, Missouri.

According to preliminary data, the S&P 500 gained 42.70 points, or 0.80%, to end at 5,406.06 points, while the Nasdaq Composite gained 107.78 points, or 0.64%, to 16,832.24. The Dow Jones Industrial Average rose 312.82 points, or 0.78%, to 40,525.53.

The CBOE Volatility Index, Wall Street's "fear gauge," eased from eight-month highs hit last week.

Markets will be closed on Good Friday, but this week is still expected to bring some key results from U.S. companies.

U.S. companies have begun to report results for the 2025 first quarter and, with tariff troubles looming, corporate executives may hold back on giving much guidance.

"Everybody knows the future is going to look a fair amount different than the past, and management teams are going to be really hesistant to commit to much," Ellerbroek said.

Still, shares of Goldman Sachs rose on Monday after the bank reported higher first-quarter profit. Quarterly earnings from companies including Netflix and UnitedHealth Group are also on the radar this week.

Also gaining were some drugmakers after Pfizer said it would end the development of its experimental weight-loss pill.

(Reporting by Caroline Valetkevitch in New York; Additional reporting by Lisa Mattackal and Purvi Agarwal in Bengaluru; Editing by Shinjini Ganguli, Pooja Desai and Matthew Lewis)