Upstream market structure and downstream partial ownership

Existing studies on partial ownership usually overlook the effects of vertically related markets. Our paper highlights the importance of the upstream market on downstream firms' incentives to acquire partial ownership and the consequent welfare implications. In the main model, we assume that there are three firms in the downstream market, two of which may form a partial ownership arrangement. We find several results that are in contrast to those in the literature. First, the two firms will engage in partial ownership if the upstream market is an oligopoly (triopoly or duopoly). Second, partial ownership may raise total production, consumer surplus, and social welfare. This happens when the upstream market consists of a duopoly and the two firms involved in partial ownership are supplied by different suppliers. Third, the outsider, commonly known as a free rider in the literature, may become a victim of partial ownership. Our results are robust to several extensions, including a general n $n$‐firm framework, product differentiation, and uniform pricing by upstream firms. We also provide the conditions under which the curvature of the demand function and the convexity of the cost function motivate firms to form partial ownership.