This paper generalizes the frequently used Hotelling model for two-sided markets in order to determine the equilibrium market shares. We show that advertisement levels depend neither on the media price nor on the location of the media firm. An increase in advertising revenues does not change...

We extend structural gravity models of bilateral trade flows to oligopolistic competition. We show that conventional gravity estimates do not only reflect trade costs but also market power. Our simple estimation procedure generalizes the standard gravity model and disentangles exogenous trade...