“The ratings agencies were paid by the issuer of the CDO every time they rated one: the more CDOs, the more profit. A virtually unlimited number of CDOs could be created by combining different types of mortgages—or when that got boring, combining different types of CDOs into derivatives of one another. Rarely did the ratings agencies turn down the opportunity to rate one.”
Excerpt From: Nate Silver. “The Signal and the Noise: Why Most Predictions Fail-But Some Don’t.”