This paper summarizes the peculiarities of online markets and discusses recent antitrust cases related to online markets. Following a brief description of the online markets' characteristics and potential tendencies for concentration the paper first discusses the antitrust allegations and...

This paper studies competition in the German market for mobile telecommunications, motivated by recent suggestions that T-Mobile and Vodafone possess a position of collective dominance. Allegedly, their position of joint dominance is secured through a combination of first-mover advantages and...

This paper explores the effects that collusion can have in newspaper markets where firms compete for advertising as well as for readership. We compare three modes of competition: i) competition in the advertising and the reader market, ii) semi-collusion over advertising (with competition in the...

Das Internet ist stark durch Wettbewerb zwischen Plattformen geprägt, welche potenzielle Tauschpartner zusammenbringen. Die Konkurrenz zwischen solchen mehrseitigen Plattformen und die Marktkonzentration wird maßgeblich bestimmt durch (1) die Stärke der indirekten Netzeffekte, (2) das Ausmaß...