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.
Views expressed in the paper are those of the authors and do not necessarily reflect those of the Bank of Japan or Institute for Monetary and Economic Studies.