During the last decades the face of retailing has changed as a result of an ongoing concentration process and the emergence of increasingly large-scale retail outlets. Retailers constitute, therefore, “strategic gatekeepers” to final consumer markets providing them with buyer power vis-à-vis their suppliers. By preventing market entry, existing retail regulations have further strengthened the dominant position of retailers. In order to overcome the potential abuse of buyer power and thus to circumvent the induced inefficiencies, competition among retailers has to be encouraged. This gains in importance since the retail sector is also characterized by a strong internationalization process affecting both the worldwide spread of retail companies as well as their procurement strategies. In this regard, downstream competition is the only way to compensate the missing global legislation and jurisdiction.