What is the name of the 1914 US antitrust law that prohibited price discrimination and exclusive dealing?

The 1914 US antitrust law was the Clayton Antitrust Act.

President Woodrow Wilson signed the Clayton Act on October 15, 1914, alongside the Federal Trade Commission Act. Congress designed it to strengthen the Sherman Antitrust Act of 1890, whose broad language did not always clearly identify particular anticompetitive practices. The Clayton Act addressed practices including certain mergers, interlocking directorates, tying arrangements, exclusive dealing, and price discrimination.

There is an important historical nuance: the original Clayton Act’s price-discrimination provisions were later strengthened and revised by the Robinson-Patman Act of 1936. That later statute is why Robinson-Patman is often associated specifically with discriminatory pricing, but it is not the name of the 1914 law in this question.

The Federal Trade Commission Act also dates from 1914, but it created the FTC and prohibited unfair methods of competition rather than serving as the canonical answer here. The Sherman Act predates both 1914 statutes and is the foundational federal antitrust law.