Foreign exchange traders throughout Europe stayed up all night on Thursday into Friday to keep an eye on results from the UK's in/out referendum because they saw the outcome as something that could have a tremendous impact on sterling.

Traders said they would create strategies on whether to buy or sell sterling as indications from exit polls came in throughout the night.

Shortly before the polls closed sterling rose to its highest point against the US dollar this year, hitting $1.4992. Analysts said that was a sure sign the markets were anticipating a win for the Remain camp.

Richard Falkenhall, senior currency strategist at the Sweden-based bank SEB, said he would take a few hours of sleep on Thursday afternoon before returning to his desk at 9 pm Central European Time. He was ready to work throughout the night monitoring results of the vote.

At about midnight Central European Time, Falkenhall's team planned to host a client call to update the bank's customers on possible currency movements. The bank will have colleagues in Stockholm, London, New York and Singapore cooperating in executing trades.

Falkenhall said such all-nighters are rare. The last time he personally worked through the night in similar circumstances was when Lehman Brothers went bankrupt in 2008.

Because sterling has appreciated considerably in recent days, the expectation of the UK remaining within the EU has already been priced into the value of the pound, he said. Therefore, Falkenhall said sterling is not expected to move dramatically if the UK votes to remain in the bloc.

But, if Britain votes to leave, he predicts sterling could fall in value by as much as 10 percent. If that happens, trading volatilities will grow significantly.

"If we get signs of Britain potentially voting out, we would expect much more trading activities," he said.

Falkenhall added that the bank is prepared to call in as many staff as is needed throughout the night.

David Marsh, managing director and co-founder of OMFIF, a research and advisory group in London, said sterling is expected to rise momentarily on Friday if Britain votes to remain in the EU, but this may not last for long since much of the anticipated polling is already reflected in the price. And currency markets' interest in the pound could start to diminish next week when more challenges concerning Europe emerge.

Marsh said, in volatile trading, traders can potentially make profits from their trades from the past week. He said the pound has already appreciated significantly during the past few days on expectations that Britain will stay in the EU and that the pound is probably over-valued.

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