This paper provides a new theory of international capital flows. In a framework that integrates factor-proportions-based trade and financial capital flows, a novel force emerges: capital tends to flow toward countries that become more specialized in capital-intensive industries. This “composition” effect competes with the standard force that channels capital toward the location where it is scarcer. If the composition effect dominates, capital flows away from the country hit by a positive labor force/productivity shock—a flow “reversal.'' Extended to a quantitative framework, the model generates sizable current account imbalances between developing and developed countries broadly consistent with the data. (JEL F14, F21, F32, F41, L16, O19)

We show that in an open-economy OLG model, the interaction between growth differentials and household credit constraints—more severe in fast-growing countries—can explain three prominent global trends: a divergence in private saving rates between advanced and emerging economies, large net capital outflows from the latter, and a sustained decline in the world interest rate. Micro-level evidence on the evolution of age-saving profiles in the US and China corroborates our mechanism. Quantitatively, our model explains about a third of the divergence in aggregate saving rates, and a significant portion of the variations in age-saving profiles across countries and over time. (JEL E21, E22, F21, F32, F41, O16, P24)

This paper formalizes a classic idea that in second-best environments trade can induce welfare losses: incremental income losses from distortions can outweigh trade gains. In a Melitz model with distortionary taxes, we derive sufficient statistics for welfare gains/losses and show departures from the efficient case (Arkolakis, Costinot, and Rodríguez-Clare 2012) can be captured by the gap between an input and output share and domestic extensive margin elasticities. The loss reflects an endogenous selection of more subsidized firms into exporting. Using Chinese manufacturing data in 2005 and model-inferred firm-level distortions, we demonstrate that a sizable negative fiscal externality can potentially offset conventional gains. (JEL D22, F14, H25, L60, O19, P31, P33)