Welfare Consequence of Common Ownership in a Vertically Related Market

We investigate how common ownership affects welfare in a vertically related market. Although common ownership mitigates the double marginalization problem and improves welfare, it restricts competition among downstream firms and harms welfare. We find that whether common ownership is welfare-improving depends on the degree of competitiveness in the downstream market. Common ownership is more likely to improve welfare when there are fewer downstream firms and a greater degree of product differentiation. In other words, common ownership may improve welfare when competition in the downstream market is weak.