Since the bailout of Bear Stearns Cos. a decade ago this week and the failure of Lehman Brothers six months later, regulators have made it their mission to prevent a repeat. Yet even though a big financial-firm collapse in the near future is exceedingly unlikely, another crisis isn’t. Bear and Lehman were the manifestation of deeper economic forces that since the 1970s have produced crises roughly every decade. They are still at work today: Total U.S. debt, at around 250% of GDP, still stands at crisis-era peaks while debt levels in China have caught up and passed the United States… U.S. companies’ debts had reached 34% of assets by the end of 2016, the highest at least since 2000… A 1,5 to 2 percentage point increase in real interest rates, would be small by historical standards but could potentially make the debts of Italy, Greece or Portugal unsustainable. Central banks know this, of course, which is one reason they are wary of raising interest rates too quickly – while nervous that if they raise them too slowly, the problem will get worse.