Until recently, Neville Kahn, a senior restructuring expert at Deloitte & Touche, thought the worst job in his career had been wading through the mess linked to the collapse of Enron, the US energy giant.

This spring, however, Mr Kahn has been confronting an even more intractable problem, and with much wider systemic implications – namely efforts to reorganise a group of so-called structured investment vehicles (SIVs).