Wall Street’s main indexes have risen about one per cent after suffering their worst four-day percentage fall in more than a year on fears about the economic damage from the global spread of the coronavirus.

Investors were cautious as the US Centers for Disease Control and Prevention urged Americans to prepare for the virus to spread in the United States.

President Donald Trump said he will hold a news conference on the coronavirus at 6pm local time on Wednesday.

As of Wednesday, the death toll in Italy had crossed 19 and new cases in South Korea rose above 1260, while Greece and Brazil reported their first cases of the virus.

Carnegie Mellon University professor of finance Chester Spatt said it was unclear if the virus issue would be will be resolved in weeks, months or longer.

“There is potential for shock to both supply and demand sides of the economy. The magnitude of the shock is uncertain right now,” he said.

All major S&P sectors were trading higher, with technology leading the charge on a 1.6 per cent gain.

Defensive utilities, real estate and consumer staples were the laggards.

At 9.46am local time the Dow Jones Industrial Average was up 291.27 points, or 1.08 per cent, at 27,372.63 and the S&P 500 was up 39.01 points, or 1.25 per cent, at 3167.22. The Nasdaq Composite was up 138.33 points, or 1.54 per cent, at 9103.94.

The Dow has lost more than 1900 points in the past two days alone, while the Nasdaq has slid 8.9 per cent from its record peak hit last Wednesday.

The S&P 500, which is down 7.8 per cent from its all-time high, has lost about $US1.74 trillion in market capitalisation in the last two sessions, according to S&P Dow Jones Indices senior analyst Howard Silverblatt.

Among stocks, TJX Cos jumped 7.8 per cent as the off-price retailer beat quarterly same-store sales estimates.

Beyond Meat rose 6.1 per cent as Starbucks said its Canadian stores would start selling the company’s plant-based breakfast sandwich next week.

Walt Disney slipped 0.6 per cent on news Robert Iger will step down as chief executive, handing the reins to Disney Parks head Bob Chapek.

Advancing issues outnumbered decliners by a 3.63-to-1 ratio on the NYSE and by a 2.91-to-1 ratio on the Nasdaq.

The S&P index recorded one new 52-week highs and 12 new lows, while the Nasdaq recorded 10 new highs and 56 new lows.