Currency drops drastically as Britain votes to exit EU

Such a body blow to global confidence could well prevent the Federal Reserve from raising interest rates as planned this year, and might even provoke a new round of emergency policy easing from all the major central banks.

Risk assets were scorched as investors fled to the traditional safe-harbours of top-rated government debt, Japanese yen and gold.

Billions were wiped from share values as FTSE futures fell 7 percent, EMINI S&P 500 futures 5 percent and Japan's Nikkei 7.6 percent. European stock markets were set to up 6-7.5 percent lower.

The British pound collapsed no less than 18 U.S. cents, easily the biggest fall in living memory, to hit its lowest since 1985. The euro in turn slid 3.1 percent to $1.1022 as investors feared for its very future.

Nearly complete results showed a 51.8/48.2 percent split for leaving, setting the UK on an uncertain path and dealing the largest setback to European efforts to forge greater unity since World War Two.

Sterling sank a staggering 10.1 percent to $1.3387, having carved out a range of $1.3228 to $1.5022. The fall was even larger than during the global financial crisis and the currency was moving two or three cents in the blink of an eye.

"It's back to the future, we're back to where we were in 1985," said Nick Parsons, co-head of global currency strategy at NAB in London.

"We've had a 10 percent decline in six hours. That's simply extraordinary, and a vote to leave provides an existential crisis for Europe."

The shockwaves affected all asset classes and regions.

The safe-haven yen sprang higher to stand at 101.34 per dollar, having been as low as 106.81 at one stage. The dollar decline of 4 percent was the largest since 1998.

That prompted warnings from Japanese officials that excessive forex moves were undesirable. Indeed, traders were wary in case global central banks chose to step in to calm the volatility.

Bank of Japan Governor Haruhiko Kuroda said the bank was ready to provide liquidity if needed to ensure market stability and a source said the Bank of England was in touch with other major central banks ahead of the market open there.

Other currencies across Asia suffered badly on worries that alarmed investors could pull funds out of emerging markets.

RECESSION FEARS

MSCI's broadest index of Asia-Pacific shares outside Japan slid almost 5 percent, while Shanghai stocks lost 1.1 percent.

Financial markets have been racked for months by worries about what Brexit, or a British exit from the European Union, would mean for Europe's stability.

"Obviously, there will be a large spill over effects across all global economies if the "Leave" vote wins. Not only will the UK go into recession, Europe will follow suit," was the gloomy prediction of Matt Sherwood, head of investment strategy at fund manager Perpetual in Sydney.

Investors duly stampeded to sovereign bonds, with U.S. 10-year Treasury futures jumping over 2 points in an extremely rare move for Asian hours.

Yields on the cash note fell 24 basis points to 1.49 percent, the steepest one-day drop since 2009 and the lowest yield since 2012.

The rally did not extend to UK bonds, however, as ratings agency Standard and Poor's has warned it would likely downgrade the country's triple A rating if it left the EU.

Yields on 10-year gilts were indicated up 20 basis points at around 1.57 percent, meaning higher borrowing costs for a UK government already struggling with a large budget deficit.

Across the Atlantic, investors were pricing in even less chance of another hike in U.S. interest rates given the Federal Reserve had cited a British exit from the EU as one reason to be cautious on tightening.

"It adds weight to the camp that the Fed would be on hold. A July (hike) is definitely off the table," Mike Baele, managing director with the private client reserve group at U.S. Bank in Portland, Oregon.

Fed funds futures were even toying with the chance that the next move could be a cut in U.S. rates.

Commodities likewise swung lower as a Brexit would be seen as a major threat to global growth. U.S. crude shed $3.00 to $47.11 a barrel in erratic trade while Brent fell 6 percent to $47.83.

Industrial metal copper sank 3 percent but gold galloped more than 8 percent higher thanks to its perceived safe haven status.