Stable market structures from merger activities in mixed oligopoly with asymmetric costs

This paper examines endogenous merger formations in a mixed oligopoly. Applying the core as a solution concept, we analyze which market structure(s) remain(s) stable when three firms—two symmetric private firms and one inefficient public firm—are allowed to merge with each other in a mixed Cournot industry. We show that according to the value of the marginal cost of the public firm, there always exists a pair of share ratios of the owners of both the (pre-merged) public firm and the (pre-merged) private firm such that the market structure with the merger between the public firm and one private firm belongs to the core. When the initial market structure is a mixed triopoly, it can only be blocked when one public firm and one private firm merge. Furthermore, we conduct a similar analysis in a general mixed oligopoly with one public firm and n private firms.