Working Paper Ircres-CNR 11/2018. There are two fundamental philosophies of credit rating: the point-in-time and the through-the-cycle approaches. This survey consider the explanations of the three main rating agencies, Standard&Poor’s, Moody’s and Fitch, and compare them with the various quantitative models proposed in the scientific literature by researchers, consultants and regulators. Some common frameworks characterizing these models are identified and evaluated
