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This article summarizes merger enforcement data for the period between 2001 and 2020, using a database created by the authors. The database lists the identity and outcome of every transaction that received a second request during this 20-year period. The database also lists the identity and outcome of every challenge to an already-consummated merger during the period. To our knowledge, it is the only complete database for the listing and outcomes of all such transactions. The goal of creating the database is to provide further information on merger enforcement, which hopefully can inform policy and spur additional analysis. We describe the data and various results, both in aggregate and across Presidential Administrations. These include rates of second request, challenges, consent decrees, abandonments and trial outcomes. We also provide a complete listing of all merger challenges.

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Antitrust Law Journal, Vol. 85, Issue 1.