We model platform competition in a market where products are characterized by cross network externalities. Consumers differ in their valuation of these externalities. Although the exogenous set-up is entirely symmetric, we show that platform competition induces a vertical differentiation...

Many economists are aware that the conditions for the efficiency and monopolization in a partial equilibrium framework are the extremes of the Ramsey–Boiteux formula when the Lagrange multiplier for the budget varies. We formalize the duality existing between the welfarist and monopolist...