We study the gains from trade liberalization in models with monopolistic competition, firm-level heterogeneity, and variable markups. For a large class of demand functions used in the international macro and trade literature, we derive a parsimonious generalization of the welfare formula in Arkolakis et al. (2012). We then use both estimates from micro-level trade data and evidence regarding firm-level pass through to quantify the implications of this new formula.Within the class of models that we consider, our main finding is that gains from trade liberalization predicted by models with variable markups are equal to, at best, and slightly lower than, at worst, those predicted by models with constant markups. In this sense, pro-competitive effects of trade are elusive.

We develop a quantifiable general equilibrium model of trade and multinational production (MP) in which countries can specialize in innovation or production. Home market effects or comparative advantage leads some countries to specialize in innovation and relegate manufacturing operations to other countries via outward MP. Counterfactual analysis reveals that the reduction in the cost of MP or the integration of China into the world economy may hurt countries that are driven to specialize in production, although these losses tend to be very small. Contrary to popular fears, production workers gain even in countries that further specialize in innovation.