Files
Abstract
In this report I will explain how to measure relevant antitrust markets for the analysis of
the market power of the leading supermarket chains in Great Britain. Given the recent
enforcement practices of the Competition Commission and the analyses submitted by, or on behalf of, Tesco, Sainsbury, and other retailers, my explanation necessarily must also continue to
the measurement of market power. Non-coordinated competitive effects are also called
unilateral effects and I will use that term henceforth in this report. These strategic moves do not
require the cooperation of other firms. Coordinated effects (tacit collusion) do depend upon the
cooperation of other firms. The exercise of these types of market power is not mutually
exclusive (Levy and Reitzes 1993). Both types can elevate prices or otherwise distort the price,
quality, reach and service marketing mix in a market.