If Britain votes to leave the European Union, the pound is expected to drop as much as 10 percent against the dollar, according to Stacey Gilbert, head of derivative strategy at Susquehanna Financial Group.
If there's an exit vote "I would say right now in terms of the pound we're seeing a move to 8 to 10 percent on the downside. That's a huge move in terms of a currency," Gilbert said Thursday on CNBC's Power Lunch.
"If it's a stay vote it's probably 5 to 6 percent on the upside just based on where those options are being priced," she said.
The U.K. currency has already lost a considerable amount of value this year, likely in anticipation about the vote's potential outcome.
The implied odds of Britain voting to leave in the June 23 referendum rose to nearly as high as 50 percent Thursday on online betting market PredictIt, before dropping to the 35 to 40 percent range Friday.
In the currency market, the pound has not just lost value against the dollar; "compare that pound to some of the other safe haven currencies, again a similar sell-off has been happening over the last 30 days, so to a degree you're seeing some of this Brexit vote get priced in to a degree," Craig Johnson, technical analyst at Piper Jaffray, said Thursday on CNBC.