The practice of central bank foreign exchange intervention for a time ran ahead of either compelling theoretical explanations of its use or persuasive empirical evidence of its effectiveness. Research accelerated when the emerging economy crises of the 1990s and the early 2000s brought fresh data in the form of urgent experimentation with foreign exchange intervention and related policies, and the financial crisis of 2008 propelled serious treatment of financial frictions into models of intervention.
Current foreign exchange intervention models combine financial frictions with relevant externalities: with the aggregate demand and pecuniary externalities that inform macroeconomic models more broadly, and with the trade-related learning externalities that are particularly relevant for developing and emerging economies. These models characteristically allow for normative evaluation of the use of foreign exchange intervention, although most (but not all) do so from a single economy perspective.
Empirical advances reflect the advantages of more variation in the use of foreign exchange intervention, better data, and novel econometric approaches to addressing endogeneity. Foreign exchange intervention is now widely viewed as influencing exchange rates at least to some extent, and sustained one-sided intervention; and its corresponding reserve accumulation appear to play a role in moderating exchange rate fluctuations and in reducing the likelihood of damaging consequences of financial crises.
Key avenues for future research include sorting out which frictions and externalities matter most, and where foreign exchange intervention—and perhaps international cooperation—properly fits (if at all) into the blend of policies that might appropriately address the externalities.
