Theory of behavior and informational efficiency of financial markets.

Summary The thesis confronts decision theories used in economics and cognitive and social psychology and discusses their implication on the informational efficiency of financial markets. The first part presents the functioning of Bayesian learning models and more specifically of herd behavior. The second part provides an introduction to cognitive psychology and behavioral economics and finance. The third part deals with theoretical models of behavioral finance that introduce a cognitive bias in economic agents that distorts their rationality. An original model of belief discounting is proposed that conditions an information processing process on the nature of the information disseminated on the markets.