United States president-elect Donald Trump's shocking defeat of Hillary Clinton rattled world markets as investors fear the Republican's victory in the presidential election could cause economic and global uncertainty.

Global financial markets and oil prices went into a tailspin following the billionaire populist's shock election win but losses narrowed after the president-elect's conciliatory victory speech.

Markets had priced a win for Democrat Hillary Clinton, who was seen as a status quo option.

Oil prices fell in Asia, the US dollar sank and stock markets slammed into reverse in wild Asian trading.

Mexico's peso plunged to its lowest-ever levels when Trump's chances of winning the presidency increased as election results began rolling in.

Concerns of a Trump victory have weighed heavily on the peso for months because of his threats to rip up a free trade agreement with Mexico and tax money sent home by migrants to pay to build a wall on the southern US border.

There is substantial uncertainty about Trump's policy positions, as well as market scepticism over his views on topics such as trade.

Capital Economics said a Trump presidency was "very much a step into the unknown".

"Will he be the demagogue from the campaign trail who threatened to lock up his political opponents, punish the media, build border walls and start a global trade war?" the research firm said in a note. "Or is he capable of becoming a statesmanlike figure who leads in a more measured manner?"

"Trump's victory speech was conciliatory," Jeffrey Halley, a senior market analyst at OANDA, told AFP. "The market liked what he had to say about fiscal spending to rebuild America's infrastructure."

But Halley noted that “the world is still in shock” over Trump's win and would need more time to digest the potential implications.

"The downward pressure on oil could reassert itself so it's still too early to gauge any definitive views," he said.

The December contract for US benchmark West Texas Intermediate was down 53 cents at $44.45 a barrel and Brent crude for January delivery was 51 cents lower at $45.53.

Both contracts fell more than one dollar earlier in the session after Trump cemented his lead over Clinton.

European shares fell at the open on Wednesday after Trump was elected president.

The STOXX Europe 600 fell 1.1pc, but well off earlier lows. Growth-sensitive sectors such as autos, financials and oil firms were among the biggest laggards.

Initial indicators had suggested falls of up to 4pc at the open.

Shares in London-listed banks and wealth managers fell after Trumps victory.

Europe's largest lender HSBC saw its stock slide by 2.8pc as trading began, as investors fretted about its interests in the U.S. and Mexico ─ where the value of the peso has dropped to a record low versus the dollar ─ and the economic damage posed by a vast border wall the president-elect has vowed to build.

Safe havens, seen as outperforming in times of uncertainty, rose.

Swiss stocks were up 0.7pc, and health care stocks, which faced tougher regulation under a Clinton presidency, rose 2.6pc.

Healthcare stocks were the standout sector performers, up 2.4pc in early trades as potential risks to pricing practices in the US significantly reduced with a Trump win.

In Japan, the Nikkei actually opened a bit higher, but then had a horror story into the mid-session break. After that break things stabilised a bit but there was no recovery and the index closed down 5.4pc.