不平衡贸易2.0

Unbalanced Trade 2.0 Alejandro Cuñat and Robert Zymek WP/25/191 IMF Working Papersdescribe research inprogress by the author(s) and are published toelicit comments and to encourage debate.The views expressed in IMF Working Papers arethose of the author(s) and do not necessarilyrepresent the views of the IMF, its Executive Board,or IMF management. 2025SEP IMF Working Paper Research Department Unbalanced Trade 2.0Alejandro Cuñat and Robert Zymek* Authorized for distribution by Petia TopalovaSeptember2025 IMF Working Papersdescribe research in progress by the author(s) and are published to elicitcomments and to encourage debate.The views expressed in IMF Working Papers are those of theauthor(s) and do not necessarily represent the views of the IMF, its Executive Board, or IMF management. ABSTRACT:Do trade imbalances boost incomes in surplus economies at the expense of deficit economies?We show that the answer is yes in an important subclass of quantitative trade models. This is the consequenceof scale economies concentrated in the traded sector. A rise in net exports causes the traded sector to expand,which raises productivity and real income in surplus economies. The flipside is a decline in productivity andincome in deficit economies. Under plausible calibrations of the strength and incidence of scale economies,observed trade imbalances cause a sizeable redistribution of the gains from trade towards surplus economies.If these imbalances are modelled as the outcome of steady-state equilibrium in international asset markets,major deficit economies may prefer to correct their traded-sector underproduction by moving to financialautarky. However, financial autarky reduces global welfare and is generally not the optimal policy to bolster thetraded sector in the presence of scale economies. Unbalanced Trade 2.0 Prepared by Alejandro Cuñat and Robert Zymek1 1Introduction How do (changes in) trade imbalances influence economies’ real incomes? Wetake a new look at this venerable question in international macroeconomicsthrough the lens of a broad class of popular quantitative trade models.Weshow that a subset of these models is consistent with the common notion thattrade imbalances boost incomes in surplus economies at the expense of deficiteconomies.1 Depending on parameter assumptions, this may have quantit-atively meaningful implications for the distribution of the gains from trade.Having documented it, we explore some of the implications of this finding. The modern quantitative analysis of trade policy counterfactuals relies onmodels that generate a gravity equation of international trade. One appealingfeature of these gravity models is that, despite differences in microfoundations,they imply a common macro structure that relates parameter shocks to changesin trade patterns and real incomes.2Within this structure, we show that thereare two effects that relate a given change in imbalances to incomes. The first isa terms-of-trade effect, common to all gravity models. Since spending is home-biased in the presence of trade barriers, a deficit shifts demand towards theoutput of a deficit economy, which improves its equilibrium terms of trade andraises its real income. Meanwhile, a surplus economy experiences lower termsof trade and real income. This mechanism has a long pedigree in internationalmacroeconomics, harking back to Germany’s World War I reparations (Keynes,1929). However, it contradicts the view that deficits hurt the deficit economy.Instead it is the surplus economy that experiences a “double burden”, both fromtransferring consumption to the rest of the world and from a deterioration ofits terms of trade. The second is a productivity effect, which is present only if the productionof traded goods is subject to relatively strong economies of scale.A tradedeficit shifts labour towards non-traded activities, while a surplus shifts labourtowards the traded sector. In the presence of scale economies concentrated intraded production, this reduces labour productivity and real income in deficiteconomies and raises productivity and income in surplus economies. Traded-sector scale economies arise naturally in the popular Krugman and Melitzmodels.3 They can also arise from endogenous technical progress in othertrade models.4 Unlike the terms-of-trade effect, the resulting productivity effect generates an income burden for deficit economies. Moreover, since theequilibrium labour allocation in multi-sector models with scale economies isgenerally not first-best, imbalances may alleviate underproduction of tradablesin surplus economies while exacerbating it in deficit economies. Armed with these insights, we take a generalised gravity model to recenttrade and production data from the OECD Inter-Country Input-Output Data-base. In addition to conventional calibration choices, our analysis requires usto take a stance on the relative strength of scale economies in traded produc-tion.To this end, we survey the