Traditionally, vertical integration has concerned industrial economists only insofar as it affects market outcomes, particularly prices. This paper considers reverse causality, from prices – and more generally, from demand – to integration in a model of a dynamic oligopoly. If integration is costly but enhances productive efficiency, then a trend of rising prices and increasing integration could be due to growing demand, in which case a divorcement policy of forced divestiture may be counterproductive. Divorcement can only help consumers if it undermines collusion, but then there are dominating policies. We discuss well-known divorcement episodes in retail gasoline and British beer, as well as other evidence, in light of the model.
(revised version of CEPR DP 10914, November 2015)