Carnage came to world markets on Friday as major television networks said Britain had voted to leave the European Union, threatening the existence of the entire bloc and its single currency.
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 the major central banks.
Risk assets were scorched as investors fled to the safety of top-rated government debt, with FTSE futures off 7 percent FFIc1 and EMINI S&P 500 futures ESc1 down 3.6 percent.
The British pound had collapsed no less than 15 U.S. cents, easily the biggest fall in living memory, to hit it lowest since 1985. The euro in turn slid 3.4 percent to $1.0997 EUR= as investors feared for its very future.
While vote counting had not been concluded, major British television networks including ITV, the BBC and Sky News all called the result as a "Leave" and betting firm BetFair estimated the probability of leaving as high as 94 percent.
Sterling sank a staggering 9 percent to $1.3525 GBP=, having carved out a range of $1.3462 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.
"The carnage in the FX markets may continue if the leave votes pull further ahead in the lead," said Bernard Aw, markets strategist at IG in Singapore.
"Equities markets will be affected, and we can see that Asian stocks are already under a fair bit of pressure. British banks listed in Hong Kong are suffering significant losses."
HSBC (0005.HK) fell 9 percent while Standard Chartered (2888.HK) sank almost 10 percent.
The tremors shook all asset classes and regions.
The safe-haven yen sprang higher to stand at 101.52 per dollar JPY=, having been as low as 106.81 at one stage. The dollar decline of 4 percent was the largest since 1998.
That dragged the Nikkei .N225 down more than 8 percent and 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.
Other currencies across Asia suffered badly on worries that alarmed investors could pull funds out of emerging markets.
MSCI's broadest index of Asia-Pacific shares outside Japan .MIAPJ0000PUS slid almost 5 percent, while Shanghai stocks .SSEC lost 1.1 percent.
FALSE HOPES?
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.
Early opinion polls had favored the "Remain" camp and perhaps led to a false sense of complacency in markets. An Ipsos MORI poll put the lead at 8 points while a YouGov poll out just after polls closed found 52 percent of respondents said they voted to remain in the EU.
Sovereign bonds came back into favor as safe harbors against extreme market volatility, with U.S. 10-year Treasury futures TYc1 jumping 1.29 points.
Yields on the cash note US10YT=RR fell 21 basis points to 1.53 percent, the steepest one day drop since 2009.
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 GB10YT=TWEB, meaning higher borrowing costs for a 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 <0#FF:> were even toying with the chance that the next move would 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 CLc1 shed $2.02 to $48.09 a barrel in erratic trade while Brent LCOc1 fell $1.91 to $49.00.
Copper CMCU3 slipped but gold XAU= galloped more than 8 percent higher thanks to its perceived safe haven status.
