NEW YORK (AFP) - Wall Street stocks finished a roller-coaster session with modest gains Friday (May 10) after the United States and China promised to keep talking after two days that yielded no agreement.

The Dow Jones Industrial Average, which had fallen more than 350 points earlier in the day, ended at 25,942.37, up nearly 115 points or 0.4 per cent.

The broad-based S&P 500 gained 0.4 per cent to 2,881.40, snapping a four-day losing streak, while the tech-rich Nasdaq Composite Index edged up 0.1 per cent to 7,916.94.

Both US and Chinese officials described the talks as productive, with President Donald Trump vowing that "conversations into the future will continue" and Chinese Vice Premier Liu He saying that the negotiations had gone "fairly well," according to Bloomberg.

But uncertainty loomed after China suggested earlier it could respond punitively to the US decision to raise duties on US$200 billion in Chinese imports to 25 per cent from 10 per cent.

"The markets are putting an optimistic spin on very little information," said Maris Ogg of Tower Bridge Advisors.

"The message we got is more 'We'll keep talking, stay tuned,'" she added. "It creates more uncertainty and leaves the market in a limbo."

In its market debut, ride-hailing company Uber tumbled 7.6 per cent from its initial public offering price, while arch-rival Lyft slumped 7.4 per cent.

Both companies have grown rapidly despite heavy losses but some investors are skittish over their prospects for profitability.

Symantec plunged 12.5 per cent on a disappointing forecast and as it announced that Gregg Clark was stepping down as chief executive and would be replaced immediately on an interim basis by Richard Hill, a current board member.

Marriott International fell 2.8 per cent on disappointment over its outlook.