The Great Moderation and the U.S. External Imbalance

The early 1980s marked the onset of two striking features of the current world macroeconomy: the fall in U.S. business cycle volatility (the "great moderation") and the large and persistent U.S. external imbalance. In this paper, we argue that an external imbalance is a natural consequence of the great moderation. If a country experiences a fall in volatility greater than that of its partners, its incentives to accumulate precautionary savings fall and this results in a permanent deterioration of its external balance. To assess how much of the current U.S. imbalance can be explained by this channel, we consider a standard two-country business cycle model in which households are subject to business cycle shocks they cannot perfectly insure against. The model suggests that a fall in business cycle volatility like that observed in the United States can account for about 20 percent of the actual U.S. external imbalance.