Crashed: How a Decade of Financial Crises Changed the World

by Adam Tooze

The message that this communicated down the food chain was simple: We want more mortgage debt to process, and the worse the quality, the better. By the magic of independent probabilities, the worse the quality of the debt that entered into the tranching and pooling process, the more dramatic the effect. Substantial portions of undocumented, low-rated, high-yield debt emerged as AAA. In any boom, irresponsible, near criminal or outright fraudulent behavior is to be expected. But the mortgage securitization mechanism systematically produced this race to the bottom in mortgage lending quality. It was the difference between the high yield of the underlying securities included in the collateral pool and the low interest that was paid to the investors who bought the AAA-rated asset-backed securities that generated the profit.