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Net short sterling contracts rose to 51,310 in the week to April 12, the highest since June 2013, as investors added to their bearish bets on the pound for a fourth straight week.
Concerns that Britain could vote to leave the European Union at a referendum on June 23 have driven sterling down over 6 percent since the start of the year on a trade-weighted basis , with most banks saying it would fall further in the event of a Brexit.