AbstractMixed oligopolies are characterized by private and public enterprises. Previously, entry into these markets was restrictive. It has since been relaxed by deregulations, and as a result, private firms have entered mixed oligopolies. An increase in the number of private firms increases competition among them and reduces the profit of incumbent private firms, given the privatization policy remains unchanged. However, an increase in the number of private firms may affect privatization policy, and thus, indirectly affect private firms' profits. Therefore, the overall effect on private firms' profit is ambiguous. In this study, we investigate how the number of private firms affects the profit of each private firm in mixed oligopolies. We use a linear‐quadratic production cost function, which covers two popular model formulations in the mixed oligopoly literature. We show that if the degree of privatization is exogenous, the profit of each private firm decreases with the number of private firms. However, if the degree of privatization is endogenous, the relationship between the number of private firms and profit takes an inverted‐U shape under a plausible range of cost parameters. Our results imply that there can exist multiple equilibria in free‐entry markets with different degrees of privatization.