Shortly after polls closed at 10pm on Thursday the pound rocketed to 1.50 dollars, its highest performance of 2016.
But as Leave votes flooded in in increasing numbers the strength of sterling plummeted.
Chris Towner, chief economist at HiFX, said: “The momentum continues for the Leave vote with the difference between Leave and Remain widening close to one million votes.
“The networks are all calling an exit vote and the likelihood of an exit gets to 95% probability. Sterling continues to suffer with GBP/USD dealing 10% lower from its high only a few hours ago.
“It just goes to show how sensitive the currency markets are, as we were trading at 1.50 only a few hours ago and now GBP/USD is trading in the 1.33s.
“Arguably the exit vote is now priced into sterling as the UK wakes up to ‘Independence Day’.”