Explain Antitrust Policies Of Government?

Let's begin by reviewing the major elements of the economic theory that relate to government antitrust policies:
1. Imperfect competitors are inefficient because they set prices above marginal cost. The consumers in the monopolistic or oligopolistic industry are consuming less of its goods than would be the case if the goods were efficiently supplied.
2. Many industries have technologies that exhibit significant economies of scale. It would be unrealistic to try to produce the output of such industries with perfectly competitive firms, for that would require that firms be inefficiently small.
3. In the long run, most economic progress comes from technological change. According to the Schumpeterian hypothesis, large firms with considerable market power are responsible for much invention and technological change.
4. The government has taken on the responsibility of preventing monopolization from occurring and of regulating monopolies when they are inevitable. Antitrust policies attempt to prevent monopolization or anticompetitive abuses; economic regulation is used to control the exercise of monopoly power in natural monopolies.           
With the decline of economic regulation as a major tool for preventing monopolistic abuses, governments increasingly focus on promoting competition and on applying antitrust policy as the major weapons for encouraging economic efficiency in markets.