When the Bubble Bursts : Monetary Policy Rules and Foreign Exchange Market Behavior

We examine the effects of a “bubble” in the foreign exchange market, defined as an exogenous process that temporarily shifts the exchange rate away from the value implied by fundamentals. The bubble process is analogous to Bernanke and Gertler's (1999) specification of an asset price bubble. We evaluate the performance of alternative simple monetary policy rules under both bubble and no-bubble scenarios and investigate whether policymakers should react to the deviation of the exchange rate from its steady-state value. The policy experiments employ a small-scale forward-looking structural model calibrated to UK data, which we previously used in Batini and Nelson (2000). For this model, which includes an uncovered interest parity condition, we find that the appropriate response to the exchange rate is captured by the expected inflation term, provided that the response coefficient and the inflation horizon are optimized. When uncovered interest parity is relaxed, there appears to be more merit in incorporating a separate exchange rate term in the monetary policy rule