Efficiency in decentralized oligopolistic markets

The paper analyzes quantity competition in economies in which a network describes the set of feasible trades. A model is presented in which the identity of buyers, of sellers, and of intermediaries is endogenously determined by the trade flows in the economy. The analysis first considers small economies, and provides sufficient conditions for equilibrium existence, a characterization of prices and flows, and some negative results relating welfare to network structure. The second and central part of the analysis considers behavior in large markets, and presents necessary and sufficient conditions on the network structure for equilibria to be approximately efficient when the number of players is large.