How a Bad Presumption Became Too Useful to Kill
The Philadelphia National Bank (PNB) presumption refuses to die. Long criticized and widely viewed as bad policy, it survives today in slightly attenuated form, and there is no sign that Trump-appointed antitrust enforcers plan to bury it. If anything, the 2023 Merger Guidelines, still in force, double down on the presumption more than their predecessors. Public choice theory helps explain this resilience. And because merger review must by its nature more swiftly, the U.S. Supreme Court is unlikely to step in anytime soon.
Still, the story is not static. Antitrust enforcers in the second Trump administration have “signaled a real tone shift in U.S. merger enforcement” that “recognize[s] many mergers are procompetitive.” If that shift carries through to how agencies apply the PNB presumption, it could meaningfully limit the economic harm the doctrine has long threatened to impose.