Volatility trade-offs in exchange rate target zones

The volatility trade-offs (i.e. the negative relationships between exchange rate variability and the interest rate differential) exhibited in the Krugman [Krugman, P. (1991). Target zones and exchange rate dynamics. Quarterly Journal of Economics, 106, 669-682.] model depend on the assumption of uncovered interest rate parity (UIP). However, the bands for several economies in Latin America and Eastern Europe are substantially different from those within the European Monetary System (EMS), in that their parity relationship deviates from UIP and volatility trade-offs do not exist. This paper develops a graphical exposition and uses it to show that the degree of capital mobility may serve as a plausible vehicle to explain the empirical evidence found in Krugman's regime of exchange rate target zones. Based on a Fleming-type stochastic macro model, we find that when capital mobility is relatively low, exchange rate variability exhibits a positive relationship with the interest rate differential. This result can be regarded as a possible way of resolving the conflicting outcomes between Krugman's prediction and existing empirical observations.