For many products, platforms enable sellers to transact with buyers. We show that the competitive conditions among sellers shape the market structure in platform industries. If product market competition is tough, sellers avoid competitors by joining different platforms. This allows platforms to...

In many markets, user benefits depend on participation and usage decisions of other users giving rise to network effects. Intermediaries manage these network effects and thus act as platforms that bring users together. This paper reviews key findings from the literature on network effects and...

Launching and stimulating competition in telecommunications markets is an important policy goal. It contains two elements: to encourage entry and to make competition effective such that consumers benefit. The first one requires that entrants can make profits after investing in infrastructure so...

We customize the aggregative game approach to oligopoly to study asymmetric media markets. Advertiser, platform, and consumer surplus are tied together by a simple summary statistic. When media are ad-financed and ads are a nuisance to consumers we establish see-saws between consumers and...

Standard media economics models imply that increased platform competition decreases ad levels and that mergers reduce per-viewer ad prices. The empirical evidence, however, is mixed. We attribute the theoretical predictions to the combined assumptions that there is no advertising congestion and...

An oligopolistic market with vertical product differentiation is parametrized in cost parameters. This allows me to study the impact of the technology of the firms (cost parameters) on market structure, conduct, and performance. Firms which differ only by the order of the sequential move to...

This paper analyzes the effects of specific and ad valorem taxation in an industry with downstream and upstream oligopoly. We find that in the short run, i.e. when the number of firms in both markets is exogenous, the results concerning tax incidence tend to be qualitatively similar to models...

This paper analyzes the effects of specific and ad valorem taxation in an industry with downstream and upstream oligopoly. We find that in the short run, i.e. when the number of firms in both markets is exogenous, the results concerning tax incidence tend to be qualitatively similar to models...

This paper analyzes the effects of specific and ad valorem taxation in an industry with downstream and upstream oligopoly. We find that in the short run, i.e. when the number of firms in both markets is exogenous, the results concerning tax incidence tend to be qualitatively similar to models...