Section 7 of the Clayton Act, enacted in 1914 and amended in 1950, is the principal US antitrust statute governing mergers and acquisitions. Section 7 prohibits acquisitions of assets or stock where ‘the effect of such acquisition may be substantially to lessen competition, or to tend to create a monopoly’. Transactions may also be challenged under section 1 or 2 of the Sherman Act as unreasonable restraints of trade or as attempts at monopolisation. The Federal Trade Commission (the FTC) also has the authority under section 5 of the FTC Act to challenge a transaction as an ‘unfair method of competition’.