On March 20, 2011, wireless provider AT&T announced its intention to merge with T-Mobile USA, a competing wireless provider. This article reviews the economic analysis of this proposed acquisition that we carried out for Sprint and explains why the merger would have been anticompetitive. We...

In this short and mainly expository article, we explain the “hypothetical monopolist test” that has become the standard methodology for identifying relevant antitrust markets in merger cases, and discuss two approaches to implementing the test. We then focus on the implementation of the test...

Recently, a number of papers have noted the dramatic increase in the extent to which institutional investors account for the ownership of publicly-traded stock, including holding ownership stakes in multiple market rivals. This change, in turn, has raised the intriguing or disturbing possibility...

This note describes the implementation of the hypothetical monopolist ssnip test for market definition in the context of merger cases where firms produce multiple differentiated products. The test developed here represents an extension and generalization of the Katz-Shapiro and...