The Evolution and Vitality of Merger Presumptions: A Decision-Theoretic Approach

39 Pages Posted: 7 Jan 2014 Last revised: 1 Dec 2015

See all articles by Steven C. Salop

Steven C. Salop

Georgetown University Law Center

Date Written: June 22, 2015


This article reviews the formulation and evolution of the Philadelphia National Bank anticompetitive presumption through the lens of decision theory and Bayes Law. It explains how the economic theory, empirical evidence and experience are used to determine a presumption and how that presumption interacts with the reliability of relevant evidence to rationally set the appropriate burden of production and burden of persuasion to rebut the presumption. The article applies this reasoning to merger presumptions. It also sketches out a number of non-market share structural factors that might be used to supplement or replace the current legal and enforcement presumptions for mergers. It also discusses the potential for conflicting presumptions and how such conflicts might best be resolved.

Keywords: antitrust law, competition, economic theory, merger presumptions

JEL Classification: K00, K21, K29

Suggested Citation

Salop, Steven C., The Evolution and Vitality of Merger Presumptions: A Decision-Theoretic Approach (June 22, 2015). Available at SSRN: or

Steven C. Salop (Contact Author)

Georgetown University Law Center ( email )

600 New Jersey Avenue, NW
Washington, DC 20001
United States
202-662-9095 (Phone)
202-662-9497 (Fax)

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