European banks are undergoing a real-life stress test in the wake of Britain's vote to leave the European Union. Their share prices were already down 20 percent this year; since the referendum result was announced, they've doubled that decline. If the rot isn't stopped soon, Europe will have found a novel solution to the too-big-to-fail problem -- by allowing its banks to shrink until they're too small to be fit for purpose. The answer is found in the adage never let a good crisis go to waste.
The current situation should be both a motivation and an excuse to do what Europe failed to do after the 2008 collapse of Lehman Brothers brought the financial world to its knees: fix its banking system. Here's a snapshot of this year's drop in value of some of the region's biggest institutions: