An enormous amount of ink has been spilled on the mortgage market crisis, and I have contributed my share. Yet I am now convinced that the most important factor underlying the crisis, which has been in plain view all along, has been overlooked. It is the way in which the mortgage industry manages default risk.
There are, in fact, two systems for managing default risk. In both, the borrower pays a premium scaled to estimates of the risk of the transaction. But, while one system has worked well, the other has been a disaster.