US stock markets jumped on Wednesday on hopeful signs that the coronavirus outbreak in the United States was close to a peak, with health insurers getting an additional lift from Bernie Sanders' decision to suspend his presidential campaign.

Stocks opened higher after President Donald Trump said Americans might be getting to the top of the curve in relation to the outbreak.

New York Governor Andrew Cuomo said the state's efforts at social distancing were working in getting the virus under control in one of the biggest hotspots in the country.

"The key focus of peak. That seems to be on every investor's mind right now, is when will coronavirus cases peak," said Eric Freedman, chief investment officer at US Bank Wealth Management in North Carolina.

"At some point the economic considerations really start to materialise. Plus, what will that transmission mechanism be for the economy, meaning in what phase will the economy be restarted."

The Dow Jones Industrial Average rose 3.44% to 23,433.57, the S&P 500 gained 3.41% to 2,749.98 and the Nasdaq Composite added 2.58% to close at 8,090.90.

After the worst March performance for the S&P 500 in decades, the benchmark index has bounced back by nearly 23% the past two weeks, although its main indicator of future volatility remains historically high.

Stocks gained an additional lift as the healthcare sector gained ground in the wake of Sanders' decision to drop his campaign for the White House.

Sanders' embrace of a Medicare for All healthcare policy would have essentially abolished private insurance and had cast a shadow over healthcare stocks for months.

UnitedHealth Group jumped 7.98% in the biggest boost to the Dow, while Anthem climbed 10.25%.

Even with the big gains in recent weeks, in part due to massive fiscal and monetary stimulus measures, the S&P 500 is still down almost 19% from its record high in mid-February, as measures to contain the virus brought the US economy to a virtual halt.

The Federal Reserve on Wednesday released the minutes from last month's two emergency meetings.

These showed officials grew increasingly concerned by the swiftness with which the pandemic was harming the US economy and disrupting financial markets, prompting them to take "forceful action". 

The energy sector, up 6.74%, was also a bright spot as one of the best performing sectors on the day, as WTI crude settled up more than 6% on hopes of a production cut by OPEC and its allies on Thursday.

Tesla and Boeing supplier Spirit AeroSystems became the latest companies to furlough workers. Spirit's shares jumped 16.01%, while Tesla edged up 0.62%.

Advancing issues outnumbered declining ones on the NYSE by a 6.89-to-1 ratio, while the Nasdaq advancers were favoured by a 4.87-to-1 ratio.

The S&P 500 posted three new 52-week highs and no new lows, with the Nasdaq Composite recording six new highs and 21 new lows.