It is widely believed that the 1950 amendment of Section 7 of the Clayton Antitrust Act has diverted merger activity away from horizontal and into conglomerate forms. Examination of the Federal Trade Commission Large Merger Series replicates existing substantiation of this belief, but only up until 1968. Further examination of the data shows a perceptible weakening of the horizontal-merger deterrent in the following eight years. One possible explanation is that all the attention devoted to the “conglomerate problem” after 1968 implied that horizontal mergers were neither as bad nor as illegal as existing case law had made them.