The tech-rich Nasdaq Composite Index surged 2.5 percent to 10,767.09.

The Dow Jones Industrial Average added less than 0.1 percent at 26,680.87, while the broad-based S&P 500 gained 0.8 percent to 3,251.84.

Monday's rally followed analyst upgrades of several tech giants that have been big winners from the COVID-19 upheaval as more Americans work from home.

Shares of Amazon surged 7.9 percent after Goldman Sachs lifted its price target on the e-commerce giant, estimating North American revenues rose 48 percent in the second quarter.

Among other large tech companies, Apple rose 2.1 percent, Google parent Alphabet 3.3 percent, Microsoft 4.3 percent and Tesla 9.5 percent.

All will report results within the next 10 days.

"Stocks that benefit the most from social distancing and the spreading virus are doing well," said Karl Haeling of LBBW.

"Investors are hedging their bets by buying stocks that don't benefit from the economic rebound as much as they benefit from a continuation of high fear surrounding coronavirus."

United States stocks have proven resilient in recent weeks even as spiking coronavirus cases have forced some states to suspend or roll back efforts to reopen their economies. 

The strength partly reflects unprecedented stimulus from the Federal Reserve and from Congress, where another round of stimulus legislation is expected to be debated in the coming days.

Oil services firm Halliburton jumped 2.5 percent despite reporting a US$1.7 billion quarterly loss following a 46 percent plunge in revenues.

Noble Energy rose 5.4 percent as Chevron announced it would acquire the exploration and production company for $5 billion. Chevron dropped 2.2 percent.