I must disagree as to the origins if the crisis. The subprime and nontraditional mortgages that triggered the housing boom-bust were primarily financed on Wall Street through private securities and CDOs that were peddled to banks and investors around the world. (More than $1 trillion per year at peak). These mortgages were designed to blow up or require refinancing once their intro rates expired. That became impossible, of course, once home prices stopped rising. So despite the conspiracy stories you hear, the crazy loans had much less to do with CRA and the GSEs, and much more to do with mortgage fraud at origination and when risky private mortgage paper was sold throughout the system.