Abgrenzung zweiseitiger Märkte am Beispiel von Internetsuchmaschinen

Google is supposed to be the dominant player in most search markets around the world. But what is a search market? To calculate a market share of 90% or more, it has to be clear what the denominator is: Does the search market also include product search and therefore Amazon and eBay or the search for private or personal contacts like on Facebook or LinkedIn? And is this relevant? Search engines do not charge users for their services, they earn money exclusively with advertisement. Hence, may the relevant market best be defined also through the advertisement market? In this paper we investigate those questions and find that the there is no general way to define “the search market”. The size of the market strongly depends on the question at hand. It may be very cumbersome to define the relevant market according to each problem. But the importance of search engines and the dynamics of the market leave no other choice. Claims against potentially strong players may be a popular way to generate attention but for a sound antitrust analysis, a detailed and rigorous market definition is essential.