On Monday, New York Governor Andrew Cuomo outlined a phased reopening of business in the state hardest hit by the Covid-19 pandemic. California Governor Gavin Newsom said that retail businesses in the state may begin reopening as early as this week.
"Can you lift restrictions and begin to phase in economic activity and yet keep the number of cases at bay? That is what the market is focused on right now," said Quincy Krosby, chief market strategist at Prudential Financial in Newark, New Jersey.
The Dow Jones Industrial Average rose 26.07 points, or 0.11 per cent, to 23,749.76, the S&P 500 gained 12.03 points, or 0.42 per cent, to 2,842.74 and the Nasdaq Composite added 105.77 points, or 1.23 per cent, to 8,710.72.
Gains in Microsoft , Apple and Amazon were the biggest lifts for the S&P 500, following mixed reaction last week to reports from big tech names.
Energy was the best performing S&P 500 sector, rising 3.7 per cent, as oil prices gained.
"The key turnaround this afternoon stemmed from (the) California governor's optimistic tone," said Edward Moya, senior market analyst at OANDA. "Some regional openings in California helped financial markets end the day on a positive note."
"People want to believe that things are going to get better," said Rick Meckler, a partner at Cherry Lane Investments in New Vernon, New Jersey. "All these announcements of state plans to reopen has given some optimism to investors that things can only improve from here."
Oil prices jumped higher after settlement prices showed modest gains, but the strengthening safe-haven dollar and gold held their ground.
Shares of Delta Air Lines Inc , American Airlines Group Inc , Southwest Airlines Co and United Airlines Holdings Inc fell between 5 per cent and 8 per cent, among the biggest decliners on the S&P 500 after Berkshire Hathaway dumped stakes in major US airlines.
Shares of Berkshire itself fell 2.6 per cent and weighed on the S&P 500 after the conglomerate posted a record quarterly net loss of nearly $50 billion.
Buffett, whose comments are closely followed by investors, acknowledged at Berkshire's annual meeting on Saturday that the pandemic could significantly damage the economy and his investments.
"His narrative was relatively sober compared to his posture over the years," said Emily Roland, co-chief investment strategist at John Hancock Investment Management.
A flare-up in US-China tensions also pressured the market. Secretary of State Mike Pompeo said on Sunday there was "a significant amount of evidence" that the new coronavirus emerged from a Chinese laboratory. An editorial in China's Global Times said he was "bluffing".
Investors are also digesting a difficult corporate results season. With more than half of S&P 500 companies reporting so far, first-quarter earnings are expected to have fallen 12.5 per cent, according to Refinitiv data.
Shares of Tyson Foods Inc tumbled 7.8 per cent after the company said the coronavirus crisis will continue to idle US meat plants and slow production as it reported lower-than-expected earnings and revenue for the quarter.
Data on Monday showed new orders for US-made goods suffered a record decline in March and could sink further as disruptions from the coronavirus fracture supply chains and depress exports.
Declining issues outnumbered advancing ones on the NYSE by a 1.09-to-1 ratio; on Nasdaq, a 1.14-to-1 ratio favored advancers.
The S&P 500 posted no new 52-week highs and three new lows; the Nasdaq Composite recorded 18 new highs and 14 new lows.
About 9.5 billion shares changed hands in US exchanges, below the 12.1 billion-share daily average over the last 20 sessions.