This paper considers the vertical implications of horizontal diversification. Many studies have documented organizational problems following corporate diversification. We propose that selective vertical dis-integration – shifting asset ownership to agents – can mitigate rent-seeking and coordination failures in the diversified firm. We test this proposition in a particularly simple setting that allows us to isolate the effects of interest and control for the likely endogeneity of diversification: taxi fleets that diversify into the limousine, or black car, segment following a wave of entry deregulation in the early 1990s. The results show that taxi fleets are substantially more likely to use owner-operator drivers following diversification. Moreover, diversified fleets that use a greater share of owner operators are more productive than diversified fleets that own most of their vehicles. We interpret these findings as evidence that firms re-organize in response to the challenges of diversification, and that there are causal links between the horizontal and vertical boundaries of the fleet.