This post is authored by Lawrence J. White (Robert Kavesh Professor of Economics, New York University; former Chief Economist, DOJ Antitrust Division).]
The DOJ/FTC Draft Vertical Merger Guidelines establish a “safe harbor” of a 20% market share for each of the merging parties. But the issue of defining the relevant “market” to which the 20% would apply is not well addressed.
Although reference is made to the market definition paradigm that is offered by the DOJ’s and FTC’s Horizontal Merger Guidelines (“HMGs”), what is neglected is the following: Under the “unilateral effects” theory of competitive harm of the HMGs, the horizontal merger of two firms that sell differentiated products that are imperfect substitutes could lead to significant price increases if the second-choice product for a significant fraction of each of the merging firms’ customers is sold by the partner firm. Such unilateral-effects instances are revealed by examining detailed sales and substitution data with respect to the customers of only the two merging firms.
In such instances, the true “relevant market” is simply the products that are sold by the two firms, and the merger is effectively a “2-to-1” merger. Under these circumstances, any apparently broader market (perhaps based on physical or functional similarities of products) is misleading, and the “market” shares of the merging parties that are based on that broader market are under-representations of the potential for their post-merger exercise of market power.
With a vertical merger, the potential for similar unilateral effects* would have to be captured by examining the detailed sales and substitution patterns of each of the merging firms with all of their significant horizontal competitors. This will require a substantial, data-intensive effort. And, of course, if this effort is not undertaken and an erroneously broader market is designated, the 20% “market” share threshold will understate the potential for competitive harm from a proposed vertical merger.
* With a vertical merger, such “unilateral effects” could arise post-merger in two ways: (a) The downstream partner could maintain a higher price, since some of the lost profits from some of the lost sales could be recaptured by the upstream partner’s profits on the sales of components to the downstream rivals (which gain some of the lost sales); and (b) the upstream partner could maintain a higher price to the downstream rivals, since some of the latter firms’ customers (and the concomitant profits) would be captured by the downstream partner.