PRICE AND WELFARE EFFECTS OF OLIGOPOUSTIC MERGERS

When oligopolists merge, the new firm enjoys a lower cost structure than any of its premerger constituent parts. This is because of rationalization economies which are created as facilities previously operated at disparate marginal cost levels come under common control. The resultant price-decreasing force is countered by the loss of competition due to the merger. The latter can stem not only from reduction in the number of competitors, but also from the possibility that, with a more concentrated market structure, firms'conjectures about each others'reactions will move in the direction of being more cooperative. The paper shows that, under normal conditions, the effects of diminished competition outweigh those of rationalization so that a price increase will result from the merger. In addition, the equivalence of merger to the imposition of taxes is exploited to derive a market-share based test for mergers to cause welfare decreases. This complements a test proposed by Farrell and Shapiro that works only for welfare increases.