Germany's Hidden Risk

The Bundesbank has quietly lent half a trillion euros to the European Central Bank. Could that determine the fate of the euro?

Involuntary lending is what happens when your teenager figures out how to charge stuff to your credit card. The kid promises to pay for the purchases but never gets around to it, so your involuntary loan keeps getting bigger. At some point it dawns on you that you might never get your money back.

Something similar is happening in Europe, except the dysfunctional family consists of central bankers, with Germany’s Bundesbank in the role of aggrieved parent. The figures are hard to find, policymakers don’t like to talk about them, and the accounting is far from sexy. Outside of Germany, headlines have been few. But the numbers are huge—so huge that they may be one of the biggest factors in whether the euro zone hangs together or falls apart.