We study the vertical integration and sabotage decisions of a regulated bottleneck monopoly that sells "access" to independent firms and may own a subsidiary downstream. We extend the literature in four directions by: (i) endogenizing vertical integration and linking it with the intensity of vertical economies or diseconomies a la Kaserman and Mayo (1991); (ii) systematically studying how vertical economies and diseconomies affect the intensity of sabotage; (iii) showing that the intensity of sabotage is determined by either a standard Lerner condition augmented by the direct cost of sabotage or a relation between the market share of the subsidiary and the elasticity of the derived demand for access; and (iv) systematically examining the welfare effect of vertical integration.