MOREAU Ludovic

The rating of debt securities by independent appraisers is a recent practice that has subsequently played an increasing role in the set of rules that govern the activity of finance. By looking at the American historical experience, this thesis proposes a perspective on this social choice. Chapter 1 explains the origins, development, and current extent of the use of ratings in financial regulation. Chapter 2 examines the long-term profitability of the agencies and shows that the concern for regulatory rent was overvalued relative to the change in the funding structure of ratings in the early 1970s. A macroeconomic analysis highlights the structural underpinnings of the success of this "modern" rating financed by the issuers of securities. Furthermore, by replicating an identical test around the 1930s and early 1970s, Chapter 3 shows that the relationship between ratings produced and market prices appears to change as the regulatory framework evolves. Chapter 4 takes stock of the possible market failures that the rating business might exhibit and reviews the body of regulatory discussion about it. Even though it is the main vehicle for regulatory action, the regulatory use of ratings remains problematic. Conversely, it is shown that regulators taking their role as users of ratings seriously would solve many problems. The general conclusion returns at greater length to the issues of the official use of ratings and the future evolution of the rules governing finance.