The S&P 500 has inched up to a record high close and the Nasdaq Composite Index has dipped as investors weigh upbeat vaccine developments and a potential coronavirus fiscal package.

Congress remained unable to reach agreement on fresh relief for a pandemic-hit US economy on Wednesday, although some investors said bad economic news could spur policy makers to push harder for a deal.

House Majority Leader Steny Hoyer also expressed hope a deal could be reached “in the next few days”.

Signs of progress in the race to distribute a vaccine have driven US stocks higher in recent days.

In the latest upbeat development, Pfizer Inc and BioNTech’s COVID-19 vaccine got the green light for use in Britain, the first Western country to approve a shot for COVID-19. Pfizer and BioNTech both surged.

Underscoring the argument for fiscal stimulus, data showed private payrolls increased less than expected in November, likely as soaring new infections and business restrictions hampered the labor market’s recovery.

Moreover, the Federal Reserve’s Beige Book report showed “little or no growth” in four of the central bank’s 12 US districts and only modest growth elsewhere.

Any potential sign of a worsening labor market in Friday’s broader jobs report could put more pressure on Congress to agree on a stimulus package, said Ross Mayfield at Baird.

“They are watching this stuff as much as investors are,” Mayfield said.

“It could be one of those reports where bad news is good news if it spurs the right stakeholders to come to the table.”

Positive updates on coronavirus vaccine have helped investors raise bets on a swift economic rebound next year, powering the S&P 500 and Nasdaq to record highs on Tuesday.

A rotation into value stocks continued, with the S&P 500 financial index and energy index stocks gaining, while consumer staples dropped.

Unofficially, the Dow Jones Industrial Average rose 60.86 points, or 0.2 per cent, to 29,884.78, the S&P 500 gained 6.54 points, or 0.18 per cent, to 3,668.99 and the Nasdaq Composite dropped 5.74 points, or 0.05 per cent, to 12,349.37.

Getting a generous stimulus package through Congress is a top priority, President-elect Joe Biden told the New York Times.

He also said he would not immediately cancel the Phase 1 trade deal Trump struck with China.

The biggest drag on the blue-chip Dow was a slump in Salesforce.com after the software company agreed to buy workplace messaging app provider Slack Technologies in a $US28 billion ($A38 billion) deal as it bets on an extended run for remote working. Slack also fell.

Cloud data service provider NetApp Inc’s shares jumped after it forecast third-quarter profit above expectations.