Those mortgages were priced incorrectly because the derivatives market inflated their value. There were other factors that contributed certainly. The credit rating agencies certainly played a critical role, but they were incentivized to inflate their rating because of the MBS market.

The regulation of these markets was also to blame, and that’s a whole other can of beans, but again this was due mostly to the revolving door between the regulatory agencies and the investment funds that profit from lax regulation of the derivatives market.