A little more detail on the Clayton Act:
1. Price discrimination for reasons other than cost differences or to match a competitor: A firm which charges prices below those of its competitors in regions with competition and higher prices where no competition exists might be in violation of this clause.
2. Tying contracts, requirements contracts, exclusive dealing contracts: Tying contracts are contracts that require a buyer to agree to buy one good in order to be allowed to buy another. An example might be a software publisher refusing to sell its operating system to computer manufacturers who don't agree to install its web browser.; Exclusive dealing contracts prohibit purchasing any units from a competitor.; Requirement contracts require that replacement parts and service only be supplied by the original vendor.
3. Mergers that substantially reduce competition: If a merger would tend to create a monopoly it can be blocked.
4. Direct interlocking directorates: Prohibits individuals from sitting on the boards of directors of multiple firms in the same industry. Note: It does not prevent directors of two firms in the same industry from sitting on a third, unrelated board of directors.