SYDNEY - The US dollar sank and stocks plummeted as mayhem came to world markets on Wednesday as investors faced the possibility of a shock win by Republican Donald Trump that could upend the global political order.

Every new TV network projection in the US presidential election showed the race to be far closer than anyone had thought, sending investors stampeding to safe-haven assets.

Sovereign bonds and gold shot higher while the Mexican peso went into near free-fall as AP gave Florida to Trump.

As of 0335 GMT, Trump was leading Democratic rival Hillary Clinton by 36 Electoral College votes, with a tally of 167-131.

It takes 270 to win.

US stock futures recoiled more than 4 per cent, a loss reminiscent of the carnage that followed the British vote to leave the European Union in June.

Markets fear a Trump victory could cause global economic and trade turmoil, discouraging the Federal Reserve from raising interest rates in December as long expected.

Fed fund futures were even starting to toy with the idea of a cut in rates next year and it was possible the Bank of Japan and European Central Bank might be forced to ease policy further.

South Korean authorities were thought to have intervened to steady their currency, and dealers were wondering if central banks globally would step in to calm nerves.

The scale of the scare was clear in the Mexican peso, which plunged more than 10 per cent against the dollar in the biggest daily move in two decades.

"There’s a lot of panic in the market, it is definitely an outcome it was not expecting," said Juan Carlos Alderete, a strategist at Banorte-IXE.

The peso has become a touchstone for sentiment on the election as Trump’s trade policies are seen as damaging to its export-heavy economy.

But the story was very different against the safe-haven yen, with the dollar shedding 3 per cent to 102.02 yen. The euro gained 1.5 per cent to US$1.1190.

Asian stocks also skidded, with MSCI’s broadest index of Asia-Pacific stocks outside Japan down more than 3 per cent, and the Nikkei sinking nearly 5 per cent.

MASSIVE UNCERTAINTY

With voting completed in more than two-thirds of the 50 US states, the race was still too close to call in Florida, North Carolina, Pennsylvania and New Hampshire, states that could be vital to deciding who wins the presidency.

Trump held a slight lead in Florida, while Fox News projected Clinton would take Virginia.

Markets have tended to favor Clinton as a status quo candidate who would be considered a safe pair of hands at home on the world stage.

"In contrast, a Trump victory would trigger massive uncertainty that would likely undermine risk assets at least initially, which in turn could preclude a Fed rate hike this year," warned Michelle Girard, chief US economist at RBS.

Sovereign bonds flew ahead, pushing yields on 10-year US Treasury notes down 12 basis points to 1.75 per cent again the largest drop since Brexit.

It had briefly touched a six-month high around 1.8960 per cent in early trade.

In commodity markets, gold climbed 2.8 per cent to $1,312 an ounce as the dollar slid.

Oil turned tail on concerns over the global economic outlook, with US crude shedding $1.34 to $43.63 a barrel, while Brent fell $1.24 to $44.80. - REUTERS