Credit rating agencies (CRAs) are supposed to help us measure the financial risk associated with securities issues by private and public organizations which turn to the public for financing. A bond rated AAA by Standard & Poor's, for example, means that its probability of default is deemed closer to zero than securities in any other category. On the other hand, a BB rating or lower earns it "junk" status, which the issuer must compensate for by offering investors a higher yield. Clearly, the issuers who pay for these ratings would like the highest grade possible. Do they "shop" by going to Moody's or Fitch or perhaps one of the lesser-known ratings agencies if they do not like Standard & Poor's estimates? Commentators have been quick to blame the CRAs for the current financial crisis since so many securities that they rated AAA or the equivalent are now considered toxic. Professor Chester Spatt has begun building the conceptual framework needed to address the important questions now being asked about CRAs.