Impact of Horizontal Mergers on Research & Development and Patenting: Evidence from Merger Challenges in the U.S.

This paper contributes further empirical evidence on the effects of mergers on innovation using company level data. Evidence on this issue has implications for the relationship between innovation and market concentration. Our departure from previous work is that we focus on a sample of horizontal mergers whose market concentration impacts were flagged by U.S. antitrust authorities as potentially posing a problem for antitrust law compliance. We employ propensity score matching and difference-in-differences estimation to compare the innovation activities of challenged and non-challenged merger firms to a control group of non-merged firms. We use R&D, patent grants, and citation-weighted patent grants to measure the innovation activities of firms before and after a merger. Our results indicate that the post-merger innovation outcomes of firms whose mergers were challenged are lower than they would have been had the firms not merged. But for non-challenged mergers, or mergers that do not raise concerns about market concentration, post-merger innovation outcomes are not significantly different from what they would have been without a merger.