Man Group, the world's largest hedge fund manager, failed to prevent a collapse in its share price this morning, despite claiming that its flagship portfolio, which holds a third of its assets, was close to the point at which it can earn 20% performance fees again.

In its interim results, Man reported that its post-tax profit fell from $672m in the six months to September 30 last year, to $507m this year. Man's pre-tax profit fell 24% from $820m to $622m.