Law Commons^™

Horizontal Mergers, Market Structure, And Burdens Of Proof, Herbert J. Hovenkamp, Carl Shapiro

All Faculty Scholarship

Since the Supreme Court’s landmark 1963 decision in Philadelphia National Bank, antitrust challengers have mounted prima facie cases against horizontal mergers that rested on the level and increase in market concentration caused by the merger, with proponents of the merger then permitted to rebut by providing evidence that the merger will not have the feared anticompetitive effects. Although the way that concentration is measured and the triggering levels have changed over the last half century, the basic approach has remained intact. This longstanding structural presumption, which is well supported by economic theory and evidence, has been critical to effective …