Whereas the first of these two factors places very small firms at a competitive disadvantage in the free market, the second factor places very large firms at a disadvantage of a different kind. The latter effect can be seen, for instance, in the changing role of IBM, which enjoyed a dominant position in the early years of the computer hardware and software markets. Although IBM remains a major vendor of large-mainframe software, it was unable to respond adequately to developments in other segments of the information-technology market, where young upstart companies rose to prominence seemingly overnight.

The net effect of these two opposing forces is that there is an optimum size for firms in a given market, which can be exceeded significantly and consistently only through the aid of interventionist policies, such as subsidies, product regulation, trade barriers, licensing, and so forth. Assisted by such statist measures, firms can indeed enjoy restricted competition and obtain undue profits by forming coercive monopolies and cartels. The problem that antitrust law seeks to solve, in short, is fundamentally not a problem of the free market but one of interventionist systems.