The contribution of general equilibrium models for the assessment of competition policy

This thesis consists in analysing how competition policy by enhancing prices decreases, may be used to boost purchasing power and inuence income distribution. A huge literature deals with the evaluation of how entry of firms within a particular sector improves welfare. But this literature mainly relies on a partial equilibrium approach. To complete this approach, a general equilibrium view point on competition policy is called for. There have been several attempts to study the welfare eects of entry in general equilibrium economies with increasing returns to scale. However, it is not clear that pervasive unexploited increasing returns to scale exist in real economies. Therefore, it seems relevant to consider the case of "convex" economies. In this perspective, we use simple general equilibrium models to examine how competition policy - with regard to entry or mergers - aects welfare. In order to study the redistributive eects of competition policy, we consider the case where several agents supply dierent inputs (the supply of labor is rst considered as exogenous, and then endogenous). We show that competition policy is not always welfare improving for all agents.