The section of the Clayton Antitrust Act prohibiting mergers, acquisitions, and certain joint ventures where the effect may be to substantially lessen competition. The Antitrust Division of the Department of Justice (DOJ), the Federal Trade Commission (FTC), state attorneys general, and private parties may challenge transactions under Section 7. Transactions meeting certain thresholds must be notified, before closing, to the DOJ and FTC under the Hart-Scott-Rodino Antitrust Improvements Act of 1976.

For more on antitrust enforcement under Section 7, see Practice Note, How Antitrust Agencies Analyze M&A. For details on notification requirements and processes, see Practice Note, Hart-Scott-Rodino Act: Overview.