Mixed oligopoly, public firm behavior, and free private entry

We analyze a mixed oligopoly with free entry by private firms, assuming that a public firm maximizes an increasing function of output, subject to a break-even constraint. We establish an irrelevance result: whenever a mixed oligopoly is viable, then aggregate output, aggregate costs and welfare are the same with and without the public firm. However, replacing a viable mixed oligopoly with a public monopoly yields higher net welfare. Implications for privatization policy are suggested.