Is the modern, bank-light financial system better than the old one?

THE PARALLELS between rollercoasters and financial markets are plentiful. Both go up, both go down. A mountain-high climb is often followed by a stomach-churning plunge. And, on reaching the peak, some riders start to wonder whether they will make it off alive.The recent tumult in stockmarkets has brought the fairground metaphors flooding back. Should equity investors brace for a sickening lurch downwards? And as they plummet, will the groaning girders beneath them—the infrastructure underpinning markets—hold firm? The structure of finance has changed dramatically since the financial crisis of 2007-09. Every new big-dipper has to go through rigorous testing to ensure it is safe to ride. Post-crisis global markets may be about to experience a wrenching stress test of their own—though with cars packed not with dummies but actual people.