COMPETITION,REGULATION AND WELFARE IN THE PRESENCE OF NETWORK EXTERNALITIES*

In this paper we consider a simple model of an industry with network externalities, where a benefit to each consumer from network services depends on the size of the network. We first consider a single network and cover the cases with and without fixed cost of entry. We then turn to the two‐network industry, where the incumbent network and a new entrant network compete for the market and may differ both in their marginal costs and demand structures. In addition, we identify several situations where public policy may play a crucial role in sustaining socially advantageous network service provision.