The British pound would sink 9 percent against the dollar in the immediate aftermath of Britons voting to leave the European Union on June 23, a Reuters poll of foreign exchange strategists showed on Thursday.
Conversely, if they decide to remain in the 28-member union then the pound would gain 4 percent on the greenback, the survey of more than 30 currency forecasters taken in the past week found.
When asked in April how sterling would fare, median forecasts suggested it would gain the same 4 percent soon after an 'In' vote but would fall 7 percent if Britain voted to leave. Since then the 'Remain' camp appears to have gained some traction, which has supported sterling.
In the latest FX poll, the biggest predicted drop after an 'Out' vote was 25 percent while the steepest gain from an 'In' vote was 15 percent. Only one participant predicted a fall after an 'In' vote and none predicted a rise after a vote to leave.
"The (opinion) polls seem towards the 'Remain' outcome - as does our hope and forecasts - so we believe something of that is priced in," said Stefan Grosse at NORD/LB, which could explain the change in forecasts from the last Reuters poll.
Lifting the pound to a three and a half-month high against the euro and a three-week high against the dollar a series of opinion polls last week pointed to the "In" camp opening up a lead over those favouring Brexit.
However, the currency slipped on Wednesday and the cost of hedging against sharp falls in the exchange rate over the next month rose to its highest in over seven years on worries the campaign for Britain to leave was gaining the upper hand.
Last month, the Bank of England stepped up its warnings about the economic risks if Britain votes to leave, saying sterling could fall sharply, while economists are pretty much united in saying Brexit remained the biggest threat to growth.
Most respondents were based in Europe as Britain's electoral law places strict limits on political statements during official campaign periods and many regular survey respondents based in the UK declined to reply to extra questions this time.
The overall conclusions, however, were little changed from last time the question was asked when some UK-based firms responded.
Some of the world's largest macro funds are also positioned for a rise in sterling and set to benefit if Britain stays in.
The total value of the top 10 funds' assets that report to it could rise 0.55 percent if the pound gains 5 percent after a 'Remain' vote, data tracker eVestment said on Wednesday.
Sterling was trading around $1.44 earlier on Thursday and medians in a wider poll of around 60 strategists suggest it will be at $1.46 in a month's time.