I study stable structures of efficiency-enhancing joint ventures among symmetric firms. Efficiency gains that accrue to a joint venture are assumed to increase with its size. The socially efficient industrywide joint venture is the stable outcome when membership of a joint venture is open to...

We develop an equilibrium model of vertical foreclosure with the choice of input specifications. Vertical foreclosure occurs as the upstream division of the integrated firm makes a specialized input for its sister downstream division while it would, as an independent firm, provide a generalized...