You’re in an inspirational mood; your creative juices are flowing. Before you lies a crisp, blank sheet of paper; in your hand a freshly sharpened pencil. Your task is to design an investment bank from scratch. What would you come up with? One thing’s for certain: your new creation would look very different from the existing crop of specimens.

Economic headwinds and regulatory changes have certainly played their part in challenging existing business models. But the biggest problem banks face is their own structural inefficiencies, which were both exacerbated and camouflaged by the boom years and have been exposed in all their mutant horror by the downturn.