Consultants have been accused of encouraging banks such as Citigroup and UBS to drive fixed-income trading too hard during the credit boom. But sometimes it pays not to shoot the messenger. In the event, the real killer was Goldman Sachs envy as its erstwhile rivals became obsessed with closing the gap.

At congressional committee hearings in Washington last week it emerged that Citigroup management decided to grow in fixed income after a 2005 study by an external consultant, believed to be Oliver Wyman, identified this as a gap in its business.