Essais sur les frictions financières dans les modèles d'équilibre général dynamique

This Dissertation examines the effect of financial market imperfections on the Macroeconomy. More particularly, it focuses on the consequences of equilibrium default using a Dynamic General Equilibrium approach.     The first paper builds a dynamic general equilibrium model  that emphasizes banks' comparative advantage in monitoring financial distress in order to explain firms' choice between bank loans and market debt. Banks can deal with financial distress more cheaply than bond holders, but this requires a higher initial expenditure proportional to the loan size. In contrast, bond issues may involve a small fixed cost. Entrepreneurs' choice of bank or bond financing depends on their net worth. The model  can explain why smaller firms tend to use more bank financing and why bank financing is more prevalent in Europe than in the US. The first fact can be explained by the negative link between the net worth of a business and its default probability. Explaining the second fact requires taking into account the higehr fixed cost of issuing market debt in Europe.     The second paper examines the possibility of feedback effects between between the financing constraints of households and of firms. A positive interaction between the financial strength of household and firm balance sheets may amplify aggregate shocks and increase the persistence of aggregate fluctuations. I develop a new model that incorporates both firm and household external finance spreads and time varying leverage. Contrary to a common intuition, the baseline Real Business Cycle model with credit constraints produces a small negative interaction between the costs of external financing for firms and households. The key factor in this result is the effect of changes in the external finance premium on borrowers' labour supply and the demand for loans. The reduction in households' cost of borrowing in a boom decreases labour supply and raises houshold loan demand. This increases interest rates, crowds out investment, and raises borrowing costs for financially constrained firms.     The third paper integrates household financing frictions with bank financing frictions and house price fluctuations in a dynamic general equilibrium model. The key assumption in the model is that a bank cannot fully diversify shocks, leading to a link between household and bank sectors' default risks. The cyclical behaviour of banks' external funding cost is determined by two main factors. On one hand, booms improve the financial health of the banks' borrowers which tends to reduce the cost of bank funding. On the other hand, consumption smoothing by savers and borrowers during booms increases the proportion of external financing in the banks' balance sheet which tends to increase the cost of bank funding. As a result of these opposing effects, the model matches procyclical profits and leverage in the financial sector, as observed in the data, but for non financial shocks the banking frictions in the model have an insignificant impact on the main macroeconomic aggregates such as output, consumption and investment.

Keyphrases: Frictions financières, Financial frictions, Costly state verification, Financial distress, External finance premium, Business cycle, Credit constraints, Bank capital