There’s a fascinating new working paper at the NBER that examines how the confluence of ratings and regulation conspired to help create the 2008-2009 global financial crisis (abstract):
Rating Agencies
Harold Cole, Thomas F. CooleyFor decades credit rating agencies were viewed as trusted arbiters of creditworthiness and their ratings as important tools for managing risk. The common narrative is that the value of ratings was compromised by the evolution of the industry to a form where issuers pay for ratings. In this paper we show how credit ratings have value in equilibrium and how reputation insures that, in equilibrium, ratings will reflect sound assessments of credit worthiness. There will always be an information distortion because of the fact that purchasers of ratings need not reveal them. We argue that regulatory reliance on ratings and the increasing importance of risk-weighted capital in prudential regulation have more likely contributed to distorted ratings than the matter of who pays for them. In this respect, much of the regulatory obsession with the conflict created by issuers paying for ratings is a distraction.
Skipping over the math, what Cole & Cooley observe is that credit ratings and rating agencies continue to function pretty well, even under the potential conflict of interest arising from the “issuers pay” model, at least for “vanilla” credit securities.