Many believe that wild greed and market failure led us into this sorry mess. According to that narrative, investors in search of higher yields bought novel securities that bundled loans made to high-risk borrowers. Banks issued these loans because they could sell them to hungry investors. It was a giant Ponzi scheme that only worked as long as housing prices were on the rise. But housing prices were the result of a speculative mania. Once the bubble burst, too many borrowers had negative equity, and the system collapsed.

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