Investment banks have an enviable reputation for reinvention. It is astonishing what highly intelligent people motivated by lots of money can achieve. The history of the industry is littered with firms that have tried, succeeded for a bit, failed, cut their losses, licked their wounds and then tried again. Sometimes the cycle includes a merger, disposal or a rebranding. But banks have a habit of bouncing back.

This is partly the result of an ability - like lizards shedding their tails when threatened - to shrink underperforming businesses at the drop of a hat and scale them back up again almost as quickly. Merrill Lynch turned such chop and change tactics into an art form: fire a whole load of bankers or traders, cryogenically freeze a business, then staff up again when conditions become more propitious.