This paper analyzes the optimal antitrust policy in the context of a patent race. In a simplified model, we identify the conditions under which allowing cooperation yields greater welfare than imposing competition. In view of our results, we discuss, critically, the current European policy towards R&D cooperation.Competition, Product innovation, Antitrust policy, Joint ventures, Knowledge externalities,

Motivated by the fact that some regulations involve extra costs for those firms at a size beyond a critical threshold, this paper contributes to the analysis of the welfare distortions due to these regulations. In the context of a duopoly, our results show that social welfare is not monotonic with the regulatory threshold. In particular, we obtain the paradoxical result that a policy decision of increasing the threshold might involve a dramatic decrease in welfare in some markets. An interesting consequence of this result is that the positive discrimination towards small firms is a rather subtle issue. Our results suggest that the relevant regulatory thresholds should differ across industries. Apparently, this is taken into account in some countries (e.g., USA), but not in many other countries. ResumenMotivado por el hecho de que con frecuencia algunas regulaciones implican un coste extra para las empresas cuyo tamaño supera un cierto umbral, este trabajo analiza los efectos sobre el bienestar de estas regulaciones. En el contexto de un duopolio, nuestros resultados muestran que dichos efectos no son monótonos en el umbral regulatorio. En concreto, obtenemos el resultado paradójico de que la decisión regulatoria de elevar un poco el umbral puede generar reducciones abruptas del bienestar. Una consecuencia interesante de Estudios de Economía, este resultado es que la discriminación positiva hacia las empresas pequeñas es un asunto muy sutil. Los resultados sugieren que los umbrales regulatorios relevantes deben diferir entre sectores. Aparentemente, esto se tiene en cuenta en algunos países (como EE.UU.) pero no en muchos otros.Palabras clave: Duopolio, bienestar, tamaño empresarial, efectos estratégicos.Clasificación JEL: L11, L13, L52.

Many economic booms have been accompanied by real exchange rate appreciations, large trade deficits -which have sometimes persisted after the return to the initial exchange rate parity-and a deteriorating traded sector. Those circumstances have typically raised the question of the desirability of some stabilization policy. We show that the dynamics induced by an expected productivity shock in an economy where the capital stock is non-mobile across sectors, match those circumstances. Furthermore, we obtain that credit market imperfections tend to exacerbate trade deficits, and to cause an inefficient capacity reduction in the traded sector. Some stabilization policies are explored. (JEL Classification: F41, F43, E62)

No abstract