Reading The Big Short by Michael Lewis was illuminating. Essentially, the ratings agencies have done pretty well over the years on corporate and government bon

Reading The Big Short by Michael Lewis was illuminating. Essentially, the ratings agencies have done pretty well over the years on corporate and government bonds. There is a lot of quality historical data, and a relatively small number of institutions involved. Their models broke down when it came to mortgages and how thousands (millions?) of loans hang together. But that doesn't mean their models of corporate/government debt don't still hold up.