A common approach to merger simulations used in antitrust cases is to calibrate demand from market shares and a few additional parameters. When the products involved in the merger case are differentiated along several dimensions, the resulting diversion ratios may be very different from those...

In this article, I employ a linear differentiated demand model to demonstrate the risks associated with using market shares as a proxy for diversion ratios when calculating the unilateral effects of a merger. In particular, when pro-rata market shares are not adjusted for recapture rates, the...

Merger policy is the most active area of U.S. antitrust policy. It is now widely believed that merger policy must move beyond its traditional focus on static efficiency to account for innovation and address dynamic efficiency. Innovation can fundamentally affect merger analysis in two ways....

The U.S. Horizontal Merger Guidelines and guidelines issued by enforcement agencies around the world employ the hypothetical monopolist paradigm to delineate relevant markets, but they provide only an imprecise and incomplete algorithm for implementing that paradigm. This paper fills the gap by...