At 8am on September 15 last year, a familiar question spread like wildfire through the City of London and other financial centres worldwide: Could this happen to us?

UBS had just revealed a multibillion dollar loss from "unauthorised trading" in its investment bank. Kweku Adoboli, a senior trader on the bank's London exchange-traded funds desk, had lost $2.3bn through speculative bets hidden by fictitious hedges.