The argument of this paper is simple: from an economic policy point of view, there is nothing special about market power on the buyer side of markets. In particular, we reject the contention that retail sector buying power requires different treatment from antitrust authorities compared to other sectors in the economy. Likewise, we find arguments contending that ‘buyer power’ requires that new or different laws be enacted or judicially developed ultimately unpersuasive. This paper is divided into three parts. Part I summarizes the relevant economics of buyer power, and more generally, monopsony. Part II compares the relevant antitrust treatment, in the U.S. and Europe, with respect to buyer power and competition policy. Part III applies our legal and economic insights to supermarket competition