For the past 20 years, banks have been piling up risk, making more and more loans based on less and less capital. Years of economic growth, shallow recessions and record-low default rates lulled bankers into thinking that the future would resemble the immediate past, at least as far as risk went. Turns out it didn't. All it was going to take was a worse-than-average recession — and it looks as though we've got one — and many banks, including a number of the biggest ones, were bound to fail. The shockingly poor lending standards — housekeepers being approved for million-dollar mortgages — have only hastened their demise. "This crisis needs to be understood as something that has developed over the past decade," says Joseph Mason, a finance professor at Louisiana State University's E.J. Ourso College of Business.