Essays on economic theory in asymmetric information.

Summary This thesis deals with three different topics of the asymmetric information aspect, more particularly with adverse selection: study of the "relationship banking" in the framework of competition between banks . introduction of the shares of a firm in the stock market (conflicts of interest between the issuing firm, the financial firm in charge of the sale and the investors) . mechanism of the optimal pricing of a monopoly with budget constrained consumers and proposal of a new approach of this problem of the two-dimensional asymmetric information.