Which type of merger is most likely to violate Section 7 of the Clayton Act?

A horizontal merger is most likely to violate Section 7 of the Clayton Act because this section specifically addresses mergers and acquisitions that may substantially lessen competition or create a monopoly in any line of commerce. A horizontal merger occurs between companies that are in the same industry and at the same stage of production. When two competitors combine, they may eliminate competition in that market, leading to reduced options for consumers, higher prices, or lowered innovation.

The Clayton Act aims to prevent such outcomes by regulating mergers that could lead to excessive market concentration. Therefore, when assessing potential mergers, horizontal mergers are scrutinized closely to ensure they do not harm competitive dynamics in the marketplace.

In contrast, vertical mergers occur between companies at different stages of production within the same industry, and conglomerate mergers involve companies in different industries. While these types may raise concerns, they are less likely to directly reduce competition in the same way that horizontal mergers do. Franchisor-franchisee agreements are also generally not considered mergers in the traditional sense, and thus are less likely to invoke the same regulatory scrutiny under the Clayton Act.