Die Frage nach der Kausalität fällt in die Methodologie. Methodologie ist in den Wirtschaftswissenschaften ein Bereich, der sowohl bei Ökonomen als auch bei Philosophen kaum Beachtung findet. Ökonomik hat sich ursprünglich als eine kausal erklärende Wissenschaft verstanden. Sie wollte für...

Why did rating agencies do such a bad job rating subprime securities? The conventional answer draws heavily on the fact that ratings are paid for by the issuers: Issuers could, and do, “buy” high ratings from willing sellers, the rating agencies. The conventional answer cannot be wholly...

We study credit ratings on subprime and Alt-A mortgage-backed-securities (MBS) deals issued between 2001 and 2007, the period leading up to the subprime crisis. The fraction of highly rated securities in each deal is decreasing in mortgage credit risk (measured either ex ante or ex post),...

We study risk and return characteristics of CDOs using the market standard models. We find that fair spreads on CDO tranches are much higher than fair spreads on similarly-rated corporate bonds. Our results imply that credit ratings are not sufficient for pricing, which is surprising given their...