Fears over a possible Brexit have led to volatility in the currency market, but if you examine the pound's movement over recent months, all signs point to a vote by Britain to stay in the European Union, trader Jon Najarian said Thursday.

When U.K. Prime Minister David Cameron announced the referendum on the matter in February, the pound slid "rather dramatically" and broke through $1.39 to the U.S. dollar, Najarian said in an interview with CNBC's "Power Lunch."