The Philadelphia National Bank Presumption: Merger Analysis in a Dynamic Economy

51 Pages Posted: 10 Oct 2018

See all articles by Peter Carstensen

Peter Carstensen

University of Wisconsin Law School; American Antitrust Institute

Date Written: October 4, 2015


From its decision in 1963 until at least 1974, and arguably down to the present, the Philadelphia National Bank' (PNB) presumption of illegality of mergers that result in significant increases in concentration in an already concentrated market has been central to the resolution of merger cases.* Yet when one reads the decision, it is striking that so little is actually said about the basis or strength of the presumption. Indeed, the bulk of the text and the dissents are devoted to the esoteric question of whether or not bank mergers were to be subject to the Clayton Act or only to the Sherman Act. Nevertheless, the decision's significance rests on its articulation of the presumption of illegality.

Keywords: antitrust, presumption of illegality, doctrinal history

JEL Classification: K10, K21

Suggested Citation

Carstensen, Peter C., The Philadelphia National Bank Presumption: Merger Analysis in a Dynamic Economy (October 4, 2015). Antitrust Law Journal, Vol. 80, 2015; Univ. of Wisconsin Legal Studies Research Paper No. 1457. Available at SSRN: or

Peter C. Carstensen (Contact Author)

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