Asian share markets turned skittish and S&P futures wobbled on Wednesday as results from the US presidential election showed an agonisingly close race with no clear winner yet in sight.

Investors had initially wagered that a possible Democratic sweep by Joe Biden could ease political risk while promising a huge boost to fiscal stimulus, hitting the safe-haven dollar and bonds.

But the mood quickly sobered on signs President Donald Trump could well snatch Florida and was much closer in other major battleground states than polls had predicted.

“In typical election risk-driven fashion it's been the stairs up and express elevator down as early results, especially out of Florida, are pointing away from the quick Biden outcome markets were looking for,” said Stephen Innes, Chief Global Markets Strategist at Axi. ”Markets have taken a step back from the Democratic sweep scenario.”

Instead, investors were now hedging against the risk of a contested election or at least a drawn-out process as mail-in ballots were counted.

That saw 10-year Treasury yields dive all the way back to 0.80 per cent, from a five-month top of 0.93 per cent. The fall of 7 basis points on the day was the largest since mid-May.

E-Mini futures for the S&P 500 veered wildly between negative and positive and were last up 0.36 per cent. EUROSTOXX 50 futures lost 0.5 per cent and FTSE futures 0.8 per cent.

Japan's Nikkei was still ahead by 1.4 per cent, but MSCI's broadest index of Asia-Pacific shares outside Japan shed 0.6 per cent.

“It's a wait-and-see,” said Matt Sherwood, head of investment strategy at Perpetual in Sydney.

“I think the odds of a clean (Democrat) sweep are diminishing, almost by the minute. That reduces the possibility, or the likelihood at least of a large stimulus program being agreed to in the first days of a Biden administration.”

The US dollar likewise reversed early losses and climbed 1 per cent on a basket of currencies to 94.071. The euro fell back hard to $1.1634 and away from a top of $1.1768.

Investors are still awaiting the outcome of Federal Reserve and Bank of England meetings this week, which are expected to at least give a nod to further stimulus.

The Reserve Bank of Australia on Tuesday cut interest rates to near zero and boosted its bond-buying program, adding to the tidal wave of cheap money flooding the global financial system.

Gold had recently been buoyed by all this liquidity but ran into profit taking on Wednesday, losing 1.1 per cent to $1886 an ounce.

Oil prices pared their early gains as the election outcome turned murky.

US crude were up 43 cents at $38.09, with Brent crude futures also gaining 43 cents to $40.14.