Exchange Rate Dynamics In A Continuous Time Model Of Uncovered Interest Parity With Central Bank Intervention

We study a simple continuous-time model based on uncovered interest parity (UIP) that endogenously generates conditional heteroskedasticity in exchange rate returns. The volatility clustering arises from dependence of the ex post deviation from UIP on the lagged interest differential which is induced into discretized observations that conform to sampling intervals of the data. This dependence has a quot;big newsquot; interpretation. The model also provides an explanation of the forward premium anomaly as a result of sporadic central bank intervention that creates unanticipated switches in the process governing the interest differential.

For about three decades until the Global Financial Crisis (GFC), Covered Interest Parity (CIP) appeared to hold quite closely—even as a broad macroeconomic relationship applying to daily or weekly data. Not only have CIP deviations significantly increased since the GFC, but potential macrofinancial drivers of the variation in CIP deviations have also become significant. The variation in CIP deviations seems to be associated with multiple factors, not only regulatory changes. Most of these do not display a uniform importance across currency pairs and time, and some are associated with possible temporary considerations (such as asynchronous monetary policy cycles).

We estimate an empirical model of exchange rates with transitory and permanent monetary shocks. Using monthly post-Bretton-Woods data from the United States, the United Kingdom, and Japan, we report four main findings: First, there is no exchange rate overshooting in response to either temporary or permanent monetary shocks. Second, a transitory increase in the nominal interest rate causes appreciation, whereas a permanent increase in the interest rate causes short-run depreciation. Third, transitory increases in the interest rate cause short-run deviations from uncovered interest-rate parity in favor of domestic assets, whereas permanent increases cause deviations against domestic assets. Fourth, permanent monetary shocks explain the majority of short-run movements in nominal exchange rates.

A flexible instrument to insure against adverse exchange rate movements are options on foreign currency. Often a relatively simple foreign currency option valuation model is used to address issues related to the pricing and hedging of such options. The results of many empirical studies document that real-world foreign currency option premia deviate from those predicted by the baseline model. In the first part of the book, it is shown that a noise trader model can help to explain the observed mispricing of the baseline foreign currency option pricing model. In the second part of the book, it is studied how policymakers can exploit the pricing errors of the baseline model. In particular, it is examined how option pricing theory can be applied to assess the effectiveness of central bank interventions in the foreign exchange market. To this end, a model is constructed to analyze the effectiveness of the interventions conducted by the Deutsche Bundesbank during the Louvre period.

A number of macroeconomic models of open economies under flexible exchange rate assume a strong version of perfect capital mobility which implies that currency speculation commands no risk premium. If this assumption is dropped a number of important results no longer obtain. First, the exchange rate and interest rate cannot be in steady state unless both the government deficit and current account equal zero, not simply their sum, as would otherwise be the case. Second, even in steady state the domestic interest rate can deviate from the foreign interest rate by an amount which de ends upon relative domestic asset supplies. Finally, introducing risk aversion on the part of speculators can reduce the response on impact of the exchange rate to changes in domestic asset supplies. In this sense rational speculators, if they are less risk averse than other agents, can destabilize exchange markets.

This paper reviews the empirical evidence on violations of uncovered interest parity and explores whether the evidence is consistent with the behaviour of speculative bubbles. The problem of testing for bubbles in exchange rates, without an accepted model of fundamentals, are then examined and a variety of tests are suggested. Extensive tests are run using weekly forward rate and survey data for seven major exchange rates. Results are presented.