William Hill is now offering 10/3 on a Leave vote, down from 4/1 within two days. Meanwhile, Betway has cut its odds from 4/1 to 3/1, while Remain has drifted to 2/9, from 1/8.
Betway’s Alan Alger, said: "Recent polls have persuaded punters to hedge their bets back in the Leave camp and we’ve trimmed the odds of Brexit."
And Sporting Index witnessed a frenzy yesterday of punters selling Remain’s vote share.
Ed Fulton, political trading spokesman for Sporting Index, said: "The release of ICM’s latest polling triggered a frenzy of activity on our Brexit markets, with the vast majority of punters selling the Remain camp’s vote share.
"Our markets now indicate that the David Cameron-backed campaign will narrowly win the referendum with 53.5 per cent of the vote – a low water mark for Remain. However, three weeks is a very long time in politics."
Yesterday Ladbrokes cut the odds of a Brexit vote after a new poll from the Telegraph found increasing support for the Leave campaign.
A new Ipsos Mori poll has also found that two-thirds of Britons surveyed feel they would not be worse off in the event of a Leave vote.