“At business school,” said the seasoned banker, “they teach you a simple lesson — if a company is trading for a sustained period below the value of its net assets then it should be closed down or broken up.”A study by Boston Consulting Group, due to be published next month but foreshadowed at the FT’s Global Banking Summit last week, shows an extraordinary 73 per cent of Europe’s banks are trading below their book value. The vast majority of them have been doing so for more than a decade. Welcome...