Competition law prohibits agreements and practices that restrict competition in the marketplace. This includes per se offenses like price fixing, output restrictions, and market allocation. Competition authorities analyze other agreements under the rule of reason, weighing the pro-competitive effects against anti-competitive effects. Unlawful monopolization involves the willful acquisition or maintenance of market power through predatory or anticompetitive conduct. Horizontal agreements between competitors are more likely to restrict competition than vertical agreements between companies at different stages of production.