Antitrust laws in the United States were passed to limit the economic power of large corporations that can control markets by reducing competition through concentration or through the adoption of anticompetitive methods of competition. Large corporations are not simply passive responders to the impersonal forces of supply and demand over which they have no control. They have economic power, which can be used to gain some control over market forces. Markets may fail if the dominant firms in an industry are allowed to engage in predatory practices that drive competitors out of business or if firms are allowed to interfere with competition by gaining a monopoly position.