A referendum on Brexit is not expected until the late second quarter or early third quarter and even ambitious estimates say there is just a 30% chance of Brexit coming to pass. Still, sterling remains one of the worst-performing developed market currencies in the world this year.

Rupert Harrison, chief macro strategist for multi-asset strategies at BlackRock, told MarketWatch the uncertainty surrounding the Brexit referendum could lead to more downside for the pound. Sterling is lower against the U.S. dollar and the euro over the past year.

CurrencyShares British Pound Sterling Trust