Welfare‐Increasing Monopolization*

The conditions for monopolization to be good for social welfare are examined. Social welfare can be higher when a monopoly sells to a monopoly, with double margins, than when a competitive industry sells to a downstream Cournot oligopoly with differing efficiency levels. This requires inverse demand to be sufficiently concave, and cannot hold when demand is convex. When there are no vertical issues conditions are found for elimination of an inefficient firm to raise welfare, building on Lahiri and Ono (1988). In general greater demand concavity increases the relative importance of the benefit of redistributing output to the efficient firm.