Global markets rallied on Monday after several opinion polls over the weekend showed that the "Remain" camp was regaining momentum ahead of the referendum on Britain's European Union membership on Thursday.
Polls released Monday evening for The Telegraph newspaper and The Times showed conflicting voter intentions, however. The pound was trading higher at $1.471, up from levels of around $1.40 last week.
But with markets becoming sensitive to opinion polls on the referendum, there are concerns a sharp sell-off could occur if opinion polls turn again to show a swing in favor of the leave camp.
"Financial markets appear to be taking the view that the race may well already be run, which given the twists and turns seen already in this campaign may well be extremely far sighted, or dangerously premature," Michael Hewson, chief market analyst at CMC Markets, wrote in a Tuesday note. "With more polls due out later today we can expect to see further volatility unfold in the event of a move either way."