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...

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...

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...