The Sherman Antitrust Act is a federal law that prohibits any contract, combination, or conspiracy that restrains trade or creates monopolies. In the context of real estate, antitrust violations include price fixing, market allocation, group boycotts, and tie-in arrangements.

The situation described — where two licensees agree not to show listings from a competing brokerage charging lower commissions — is a classic example of a group boycott. By conspiring to cut out competition, they are restraining trade and harming both consumers and the new brokerage.

The Equal Credit Opportunity Act (A) deals with lending discrimination, Blue-Sky laws (B) regulate securities, and federal fair housing laws (D) prohibit housing discrimination. Only the Sherman Antitrust Act applies here.

Massachusetts licensees are specifically tested on recognizing antitrust violations. The penalties for Sherman Act violations are severe, including fines, loss of license, and even imprisonment.