This article examines the effects of market structure on the variety of research projects undertaken and the amount of duplication of research. A characterization of the equilibrium market portfolio of R&D projects and the socially optimal portfolio is provided. It is shown that a merger...

This paper evaluates how different lengths of entry regulation impact market structure and market performance using a dynamic structural model. We formulate an oligopoly model in the tradition of Ericson and Pakes (1995) and allow entry costs to vary over time. Firms have the opportunity to...

When firms decide to invest in R&D, they have to choose not only the amount of resources to invest, but also which research projects to develop. This paper investigates the market portfolio of research projects. Contrary to most of the literature, which focuses only on the level of investment in...