Wall Street has gained ground and surging technology shares have pushed the Nasdaq to a record closing high as promising trial results from potential COVID-19 vaccines helped investors look beyond spiralling new cases of the disease.
Amazon.com Inc and Microsoft Corp provided the biggest boosts to the Nasdaq and the S&P500 but industrials retreated, capping the Dow's nominal gains.
Deaths in the United States from COVID-19 passed the 140,000 mark over the weekend as cases continued to rise in 42 of 50 states.
Trials of potential vaccines have shown promise.
Most recently, drugs from AstraZenica, CanSino Biologics Inc and from a partnership between Pfizer Inc and German biotech firm BioNTech were safely administered and induced immune responses.
"Developments on COVID, positive or negative, have become the new risk-on/risk-off binary trigger for the market," said Joseph Sroka, chief investment officer at NovaPoint in Atlanta. "A year ago it was trade."
"In the next few weeks there will start to be risk assessments made on how the size of the next round of financial stimulus," Sroka added.
The US Congress, still looking to mitigate the pandemic's economic effects, was set for a week of partisan wrangling over a new relief package, with two weeks until enhanced jobless benefits expire for millions of people.
The Dow Jones Industrial Average rose 8.92 points, or 0.03 per cent, to 26,680.87, the S&P 500 gained 27.11 points, or 0.84 per cent, to 3,251.84 and the Nasdaq Composite added 263.90 points, or 2.51 per cent, to 10,767.09.
Of the 11 major sectors in the S&P 500, consumer discretionary and tech enjoyed the largest percentage gains.
Second-quarter earnings season chugged along - 48 companies in the S&P 500 have posted results, with 77.1 per cent of those beating consensus, according to Refinitiv data.
In aggregate, analysts now expect S&P 500 second-quarter earnings to have dropped 43.2 per cent year-on-year, per Refinitiv.
Shares of Halliburton Co rose 2.5 per cent after the company posted a surprise adjusted quarterly profit and better-than-expected cash flow due to cost-cutting.
Noble Energy Inc advanced 5.4 per cent on news that Chevron Corp agreed to buy the oil and gas producer for $US5 billion ($A7.1 billion).
Chevron dropped 2.2 per cent.
Moderna Inc shares tumbled 12.8 per cent on positive results from its competitors' rival COVID-19 drug trials.
Electric automaker Tesla Inc rose 9.5 per cent to reach a record closing high of $US1,643.
Shares of International Business Machines Corp were up more than 5.0 per cent in post-market trading after the company's adjusted earnings came in above analyst expectations.
Declining issues outnumbered advancing ones on the NYSE by a 1.09-to-1 ratio; on Nasdaq, a 1.11-to-1 ratio favoured advancers.
The S&P 500 posted 41 new 52-week highs and no new lows; the Nasdaq Composite recorded 122 new highs and 12 new lows.
Volume on US exchanges was 9.96 billion shares compared with the 11.31 billion average over the last 20 trading days.