US stocks are nearly flat in choppy trading ahead of a crucial round of trade talks that will be held against the backdrop of additional tariffs on Chinese goods due later this week.

The United States will raise tariffs to 25 per cent from 10 per cent on $US200 billion ($A285 billion) worth of Chinese imports from Friday, according to a notice posted to the Federal Register, days after President Donald Trump threatened the duties after China backtracked on almost all aspects of a trade deal.

Still, the top Chinese trade negotiator, Vice Premier Liu He, will be in Washington for the talks on Thursday and Friday, setting up a last-ditch bid to salvage the negotiations.

“It has been a bipolar flow of information on trade. Investors are acknowledging that the negotiations are more constructive,” said Eric Wiegand, senior investment strategist at US Bank Wealth Management in New York.

“Today’s move reflects the inconclusive nature of what we are dealing with. It’s hard for investors to really position themselves after you are just hearing rhetoric and not seeing formal policies put in place.”

Boeing, the single largest US exporter to China, slipped 0.5 per cent while chipmakers, which get a large chunk of their revenue from China, also declined.

The Philadelphia chip index fell 0.24 per cent. The index has declined over 4 per cent so far this week, and is on pace to post its biggest percentage weekly loss since December 21.

The spike in tensions between the world’s two largest economies has renewed fears of a global economic slowdown and encouraged investors to seek low-risk government bonds, resulting in longer-dated US Treasury yields dropping.

Interest-rate sensitive banking stocks fell 0.31 per cent while the broader financial sector declined 0.19 per cent.

Limiting the losses were the 0.8 per cent gains in iPhone-maker Apple and Walt Disney, which is due to report results after the bell.

At 10.18am local time on Wednesday, the Dow Jones Industrial Average was up 16.91 points, or 0.07 per cent, at 25,982.00. The S&P 500 was up 1.84 points, or 0.06 per cent, at 2,885.89 and the Nasdaq Composite was up 3.11 points, or 0.04 per cent, at 7,966.87.

The benchmark S&P 500 is now more than 2 per cent away from its record high of 2,954.13 hit last week.

With results entering the final stretch, first-quarter earnings are now expected to rise 1.2 per cent, a sharp improvement from the 2.3 per cent decline expected at the start of the season.

Of the 426 S&P companies that have reported so far, about 75 per cent have beaten profit estimates, according to Refinitiv data.

Electronic Arts rose 2.9 per cent after the videogame-maker posted better-than-expected quarterly revenue, riding on the popularity of its battle royale game, Apex Legends.

Chesapeake Energy fell 1.4 per cent after the oil and gas producer’s first-quarter net loss widened, hit by a fall in production and lower crude prices.

Advancing issues outnumbered decliners by a 1.15-to-1 ratio on the NYSE and by a 1.08-to-1 ratio on the Nasdaq.

The S&P index recorded two new 52-week highs and five new lows while the Nasdaq recorded 18 new highs and 29 new lows.