Voltaire Fund, a $620m (€639m) European long/short specialist, has lost around 12% of its asset value over the course of this year, following a 6.8% loss in July.

The fund's volatile performance can be attributed to the concentrated nature of the fund's long and short positions. More than 50% of its long holdings are in just five stocks: Casino Guichard; Lonza; DSM; Grupo Dragedos and ProSieben. A single stock, Altran, contributed 90% of Voltaire's July losses.