In recent years, the audiovisual media industry has been subject to radical change. The emergence of new content aggregators like Netflix has triggered a gold rush in content acquisition. Consequently, even large media companies have become interesting merger targets resulting in increased attention of competition authorities. (deg)(deg)In merger proceedings the definition of the relevant market constitutes a crucial concept. This concept is confronted with various unique characteristics in the audiovisual media sector. To shed light on this subject Robert Bodewig analyzes and compares the European, German and U.S. competition authorities' market definition practice and discusses the specific challenges in the audiovisual media sector. New developments in the media sector are taken into account.