Informational externalities in political games and auctions.

Summary This thesis consists of two parts. The first is entitled "Optimal Organization of Political Institutions" and the second is entitled "Optimal Auctions: An Application to Finance". Both consider almost standard "principal-agent" models, in which the agent is better informed than the principal and the information that the agent possesses is valuable to the principal insofar as the principal's ability to make good decisions depends on this information. The first part analyzes the distortions caused by the existence of informational asymmetries within political systems, more specifically this informational asymmetry affecting the legislative decision-making process. We also consider the existence of a second source of distortion represented by the existence of a pressure group that actively tries to influence the choices of policy makers. We analyze here the impact of these elements on the choice of the organizational form of the political system. The second part describes an optimal auction model in which the "seller" is assumed to face two groups of differently informed buyers: one group receives a signal about the value of the good at auction and the other remains uninformed. We derive the optimal auction in which the informed buyers dream, truthfully slow to the principal their signals. We also present an application of this model to the analysis of public stock offerings.