The pound has suffered its biggest one-day fall since 2009 after the date for the EU referendum was confirmed.
Sterling fell 2.1% against the US currency to $1.41020 - the single largest one-day fall since March 2009 - and it dropped to its lowest level against the Chinese yen since November 2013.
The losses come after Mayor of London Boris Johnson announced his support for the campaign to leave the European Union, which is seen as a major dent in the campaign to remain in the Union.
Late on Friday, Prime Minister David Cameron secured a deal on EU reform following two days of intense negotiations. Following a cabinet meeting, he then called a referendum on 23 June.
Sam Hill, senior UK economist at RBC Capital Markets, said: "With political reaction to Friday's deal looking more mixed than the Prime Minister would have hoped for, in the short term it is likely that the exchange rate will be sensitive to news which is seen to increase the probability of Brexit."