Equilibria and optima generally differ in imperfectly competitive markets. While this is well understood theoretically, it is unclear how large the welfare distortions are in the aggregate economy. Do they matter quantitatively? To answer this question, we develop a multi-sector monopolistic...

We characterize the equilibrium and optimal resource allocations in a general equilibrium model of monopolistic competition with multiple asymmetric sectors and heterogeneous firms. We first derive general results for additively separable preferences and general productivity distributions, and...