This paper develops an oligopoly model with firms that may potentially be public or private, and solves it for different cases in which the number and ownership of those firms vary. The results are then compared in terms of total surplus and consumer surplus, and this comparison produces implications for the antitrust appraisal of possible mergers and acquisitions. It follows that certain types of mergers are unambiguously favorable or unfavorable from the point of view of their contribution to both total and consumer surplus, while others may be convenient in one of those dimensions but inconvenient in the other dimension.