No pressure or anything, but as you ponder whether to shut down your Asian cash equities business, close your European correlation trading desk, or pull out of the US securitisation market, are you absolutely sure that you’re not going to bring your entire investment bank crashing down around your ears?

As investment banks struggle to get to grips with a less profitable world, one way of looking at the challenge they face is to imagine they are locked in a giant game of Jenga. For those of you who missed Jenga as a child, you build a tower of wooden blocks and then have to remove the blocks one-by-one without the whole pile collapsing.