If you're planning on betting on a Brexit, now's the time to do it, after bookie Betfair put the chances of a Leave vote at 40 per cent, with odds of 6/4.
Meanwhile, the probability of a Remain vote fell to 60 per cent, giving it odds of 4/6.
That figure is the highest since it was offered at evens while David Cameron was in Brussels in March renegotiating the UK's relationship with the EU.
Betfair added punters had put £3m on the outcome of the referendum in the past 24 hours - a three-fold increase on the previous daily high.
The news came the day after William Hill offered its shortest ever odds on Brexit, with chances of a Leave vote being put at 7/4, or a 36 probability.
Yesterday it was offerig odds of 4/9 for a bet on an In vote, a probability of 69 per cent.
This morning the pound continued its fall, dropping one per cent against the dollar to $1.4125, a two-month low, as the FTSE 100 dipped below 6,000 points for the first time since March.
That came after a YouGov poll last night put the Leave side seven points ahead of Remain - while an ICM survey showed Leave could be four to six points ahead.
A survey from Fexco Corporate Payments this morning suggests two-thirds of medium to large businesses had been hit by volatility caused by uncertainty over Brexit.
“With exchange rates now more volatile than at any time in the past seven years, the Pound is being jerked around like a rag doll in a hurricane," said David Lamb, head of dealing at Fexco.
“A clear majority of medium to large British businesses feel their bottom line has been harmed by such volatility, and a sizeable minority are already considering laying off staff in the event of a vote for Brexit.
“While a depreciation in Sterling will give a shot in the arm to British exporters, importers lose out as the cost of what they buy from abroad rises."