Cette thèse contient trois études sur le fonctionnement des banques.<p>Le premier Chapitre analyse empiriquement comment la capacité d’offrir des emprunts à long terme est influencée par la dimension des intermédiaires financiers.<p>Le deuxième Chapitre analyse, avec un model théorique caractérisé par la présence de soft-budget constraint, ratchet effect et short-termism, comment la pression compétitive influence la capacité des banque de financer le firmes ayant des projets de bonne qualité.<p>Le troisième Chapitre examine, avec un model théorique du type moral hazard common agency, le conflits d'intérêts des banques universelles.<p><p>Financial intermediaries are recognized to promote the efficiency of resource allocation by mitigating problems of incentives, asymmetric information and contract incompleteness. The role played by financial intermediaries is considered so crucial that these institutions have received all over the world the greatest attention of regulators.<p>Across and within banking sectors it is possible to observe a wide variety of intermediaries. Banks may differ in their size, market power and degree of specialization. This variety raises interesting questions about the features of a well functioning banking sector. These questions have inspired an important body of economic literature which, however, is still inconclusive in many aspects. This dissertation includes three studies intending to contribute in this direction.<p>Chapter 1 will empirically study the willingness of smaller and larger lenders to grant long-term loans which, as credit to SME's, constitute an opaque segment of the credit market. Chapter 2 analyzes, with a theoretical model, the effects of competition on the efficiency of the banking sector when this is characterized by dynamic commitment issues which brings to excessive refinancing of bad quality investments (so called soft-budget constraint) or excessive termination of good ones (ratchet effect and short-termism). Chapter 3 presents a model to investigate to what extent the distortions posed by conflicts of interest in universal banks can be addressed through the provision of appropriate incentive schemes by the different categories of clients. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished