Ahmad LashkaripourDirect answer
Gains from Trade with Scale Economies
With scale economies and positive profits, the gains from trade depend on which industries expand and on whether policy coordinates that reallocation.
Parent topic: Quantitative Trade Models
Standard gains-from-trade formulas infer welfare changes from trade shares and a trade elasticity, generally under constant returns to scale. With increasing returns and positive profits, that information is not sufficient. Welfare also depends on which sectors expand and whether their expansion lowers unit costs.
The AER 2023 paper on profits, scale economies, and the gains from trade makes this dependence explicit. In a model with heterogeneous firms, increasing returns, and positive profits, trade reallocates production across sectors that differ in their scale economies. When production moves toward sectors with stronger increasing returns, constant-returns formulas understate the gains from trade. When it moves in the other direction, those formulas overstate the gains.
Coordination is central to the paper's industrial-policy result. A trade agreement can direct production toward sectors with stronger increasing returns and generate welfare gains that unilateral subsidies cannot replicate. Because scale externalities cross borders, a government does not capture the full benefit of a subsidy that lowers sectoral costs. A cooperative agreement can align national subsidies so that they complement rather than offset one another.
Factor-market distortions provide a separate channel. The JIE 2024 paper on trade and technology adoption in distorted economies shows that labor-market distortions lead firms to choose technologies that are privately rational but socially inefficient. Trade liberalization can amplify these choices, eroding roughly one-third of the productivity gains predicted by an undistorted model. A quantitative trade model therefore needs more than scale economies to evaluate policy. Whether scale effects raise welfare or are dissipated through misallocation also depends on labor-market regulation, credit frictions, and the structure of trade agreements.
Related papers
Profits, Scale Economies, and the Gains from Trade and Industrial Policy
This paper explains why unilateral trade policy is a weak tool for fixing distortions created by profits and scale economies. It argues that coordinated industrial policy inside deep agreements can be much more effective.
Trade and Technology Adoption in Distorted Economies
This paper studies how labor-market distortions change technology adoption and the gains from trade. It shows that distorted economies adopt modern technology too slowly and therefore miss a large share of trade-driven productivity gains.
Related topics
Markups, Scale Economies, and Trade
How market power and scale economies alter trade gains, industrial policy, and the returns to international coordination.
Related topicIndustrial Policy
Industrial policy in open economies, where trade links interact with scale economies, markups, and climate externalities.
Key questions
Do scale economies make trade gains larger or smaller?
Either. Trade can generate larger gains than constant-returns formulas predict when it shifts activity toward increasing-returns sectors. It can generate smaller gains when comparative advantage or policy distortions move activity away from scale-intensive sectors. The AER 2023 paper shows that coordinated industrial policy through trade agreements can direct production toward sectors with stronger scale economies and deliver welfare gains that unilateral policy cannot match. The JIE 2024 paper adds that labor-market frictions erode roughly a third of the productivity gains from liberalization. The direction of reallocation and the institutional environment therefore determine the net effect.