One of the oldest hedge fund firms in the world, whose assets are understood to have fallen by almost half over the past 18 months, has been hit by the departures of a third of its partners over the past two days. The exits include the two heads of its European business.

Five out of 15 partners are in the process of leaving Stark Investments, a $4.4bn (€3.6bn) hedge funds firm based in Milwaukee, Wisconsin with offices in London's Mayfair. The departures come after two months of discussions that ended in the past few days, according to a person close to the firm.