Asian shares are poised for a mixed opening ahead of the first US presidential debate and ongoing stimulus talks in Washington.

Australian S&P/ASX 200 futures were down 0.94 per cent in early trading, while Japan’s Nikkei 225 futures were up 0.02 per cent. Hong Kong’s Hang Seng index futures were up 0.72 per cent.

E-mini futures for the S&P 500 were up 0.04 per cent.

The first debate between former Vice President Joe Biden and President Donald Trump, set to begin at 11am AEST Wednesday, is seen by some political analysts as Trump’s best chance to upend a race where he has consistently lagged in opinion polls.

“Following the exuberant start to the week, a sober tone descended on risk markets ahead of the first US presidential debate, with caution about the outlook prevailing,” wrote Australia and New Zealand Banking Group in an analyst note.

Also looming over markets is lingering hopes the US could adopt further economic stimulus. US House of Representatives Speaker Nancy Pelosi unveiled a new, $US2.2 trillion ($A3.1 trillion) compromise relief bill in a bid to give new life to flagging negotiations with the White House.

There were optimistic signs on Tuesday when US consumer confidence saw its biggest rebound in 17 years.

The economic impact of the coronavirus pandemic was underlined later on Tuesday, when Disney announced plans to lay off roughly 28,000 US employees from its theme parks division.

Investors will also be looking at Wednesday’s ADP National Employment report, a precursor to official US employment figures out Friday. China is also set to publish fresh manufacturing data.

The Asian markets opened after US equities fell slightly hours before, ending a three-day rally as investors held tight before the debate. The Dow Jones Industrial Average fell 0.48 per cent, the S&P 500 lost 0.48 per cent, and the Nasdaq Composite dropped 0.29 per cent.

MSCI’s gauge of stocks across the globe shed 0.24 per cent following broad declines in Europe and Asia. US Treasury yields traded within a tight range as investors avoided large moves, settling down slightly.

The US dollar was also down slightly in advance of the debate, hitting one-week lows against the euro and Swiss franc. The dollar index fell 0.3 per cent.

Spot gold gained 0.9 per cent to $US1,896.96 ($A2,663.35) per ounce, while US gold futures settled up 1.1 per cent at $US1,903.20 ($A2,672.11).

Oil prices were also down on caution ahead of the debate and looming coronavirus concerns. US crude fell 4.01 per cent to $US38.97 ($A54.71) per barrel and Brent was at $US40.83 ($A57.33), down 3.77 per cent on the day.