GAM shares lost 17% of their value after the Swiss asset manager warned its underlying profits for the first six months of 2016 would be roughly half the level of a year earlier, as performance fees all but disappeared in the period.

GAM - which has been on an acquisition drive since March 2015 - blamed a projected sharp fall in performance fees for the expected profit fall in a June 14 statement, which offered further evidence that asset managers' fees are increasingly under pressure.