US stock index futures have risen slightly as investors appear to have shrugged off President Donald Trump’s threat to not sign a COVID-19 stimulus bill, while also waiting for a reading on weekly jobless claims and consumer spending data.

In a video posted on Twitter, Trump said the hard-fought pandemic relief package worth $US892 billion ($A1.2 trillion) should be amended to increase the amount in the stimulus payments to $US2,000 ($A2,649) for individuals, instead of the “ridiculously low” $US600 ($A795).

US futures had dropped as much as 1 per cent in Asian trade, before recovering later in the session.

The S&P 500 and the Dow lost ground on Tuesday as concerns over a new variant of the coronavirus in Britain and underwhelming economic data weighed on near-term sentiment. But gains in Apple Inc pushed the Nasdaq to a record close.

Investors are now looking out for the Labor Department’s weekly unemployment report due at 8:30am Eastern Time, which is expected to show a still dismal labour market as widespread business restrictions to curb the spread of new COVID-19 infections kept employers on edge.

Consumer spending data for November, also due at 8:30am ET, is expected to show weakness in spending trends because of the softer job market.

At 6:36am ET, Dow e-minis were up 69 points, or 0.23 per cent, S&P 500 e-minis were up 10.5 points, or 0.29 per cent, and Nasdaq 100 e-minis were up 18 points, or 0.14 per cent.

Easy monetary policy and increased liquidity in the market has set Wall Street’s main indexes for strong annual gains, despite a rough start to the year.

Drugmaker Pfizer Inc rose 0.5 per cent in pre-market trade after a report said it was close to striking a deal with the US government to supply at least tens of millions of additional doses of its COVID-19 vaccine candidate next year.

Supernus Pharmaceuticals Inc jumped 24.3 per cent after its experimental drug for attention deficit hyperactivity disorder met the main goal of a late-stage study in adults.

Walmart Inc fell 0.5 per cent after the US Justice Department accused the retailer of fuelling the opioid crisis in the United States.

American Airlines Group and United Airlines Holdings fell about 0.8 per cent each despite outlining plans to bring back furloughed employees this month after receiving payroll support from a recent bill.