UK's rating outlook cut by S&P

Pound buyers faced losses after the S&P warned that it was cutting its outlook for the pound from "stable" to "negative." The pound lost two percent against the dollar and 1.5 percent against the euro.

"We have revised the outlook on the UK to negative due to our view that, even assuming additional fiscal tightening, the net general government debt burden could approach 100 percent of GDP and remain near that level in the medium term," S&P credit analyst David Beers told CNBC.