The annual reports of the global custodians do not lack for lists of the many and varied risks they face. But there is one risk which overshadows all others. In fact, it is so great that custodians are not allowed to talk about it in public in any but the most meaningless way.

The one senior custodian who dared to utter the truth about this risk was relieved of his duties shortly afterwards. The issue is, of course, the disintegration of the euro.