Recent empirical research purports to show that common ownership by institutional investors harms competition even when all financial holdings are minority interests. This research has received a great deal of attention, leading to both calls for and actual changes in antitrust policy. This...

A large fraction of US public stock is held by institutional investors that frequently hold shares in multiple firms in the same industry ("common ownership"). Concerns have been raised that common ownership might harm competition if it confers influence over important strategic decisions. Using...