The Uncovered Interest Rate Parity Puzzle In The Foreign Exchange Market

The Uncovered Interest Parity (UIP) puzzle has remained a moot point since it first circulated economic discourse in 1984 and, despite a number of attempts at a solution, the UIP puzzle and other anomalies in Exchange Rate Economics continue to perplex

The currency carry trade is the investment strategy that involves selling low interest rate currencies in order to purchase higher interest rate currencies, thus profiting from the interest rate differentials. This is a well known financial puzzle to explain, since assuming foreign exchange risk is uninhibited and the markets have rational risk-neutral investors, then one would not expect profits from such strategies. That is uncovered interest rate parity (UIP), the parity condition in which exposure to foreign exchange risk, with unanticipated changes in exchange rates, should result in an outcome that changes in the exchange rate should offset the potential to profit from the interest rate differentials. Given foreign exchange market equilibrium, the interest rate parity condition implies that the expected return on domestic assets will equal the exchange rate-adjusted expected return on foreign currency assets.However, it has been shown empirically, that investors can actually earn profits by borrowing in a country with a lower interest rate, exchanging for foreign currency, and investing in a foreign country with a higher interest rate, whilst allowing for any losses (or gains) from exchanging back to their domestic currency at maturity. Therefore trading strategies that aim to exploit the interest rate differentials can be profitable on average. The intention of this paper is therefore to reinterpret the currency carry trade puzzle in light of heavy tailed marginal models coupled with multivariate tail dependence features. We analyse the returns of currency carry trade portfolios adjusting for tail dependence risk. To achieve this analysis of the multivariate extreme tail dependence we develop several parametric models and perform detailed model comparison. It is thus demonstrated that tail dependencies among specific sets of currencies provide other justifications to the carry trade excess return and also allow us to detect construction and unwinding periods of such carry portfolios.

We provide empirical evidence that deviations from uncovered interest rate parity (UIP) display significant nonlinearities, consistent with theories based on transaction costs or limits to speculation. This evidence suggests that the forward bias documented in the literature may be less indicative of major market inefficiencies than previously thought. Monte Carlo experiments allow us to reconcile these results with the large empirical literature on the forward bias puzzle since we show that, if the true process of UIP deviations were of the nonlinear form we consider, estimation of conventional spot-forward regressions would generate the anomalies documented in previous research.

This paper provides an overview of the uncovered interest parity assumption. It traces the history of the interest parity concept, summarizes evidence on the empirical validity of uncovered interest parity, and discusses different interpretations of the evidence and the implications for macroeconomic analysis. The uncovered interest parity assumption has been an important building block in multiperiod models of open economies, and although its validity is strongly challenged by the empirical evidence, at least at short time horizons, its retention in macroeconomic models is supported on pragmatic grounds by the lack of much empirical support for existing models of the exchange risk premium.

This note provides an overview of the uncovered interest parity assumption. It traces the history of the interest parity concept, summarizes evidence on the empirical validity of uncovered interest parity, and discusses the implications for macroeconomic analysis. The uncovered interest parity assumption has been an important building block in multiperiod and continuous time models of open economies, and although its validity is strongly challenged by the empirical evidence, its retention in macroeconomic models is supported on pragmatic grounds, at least for the time being, by the lack of much empirical support for existing models of the exchange risk premium.

The uncovered interest rate parity puzzle questions the economic relation existing between short term interest rate differentials and exchange rates. One would indeed expect that the differential of interest rates between two countries should be offset by an opposite evolution of the exchange rate between them, hence ruling out any limited risk profit opportunities. However, it has been shown empirically that this relation is not holding and accordingly has led, over the past two decades, to the reinforcement of a well-known trading strategy in financial markets, namely the currency carry trade. This paper investigates how highly leveraged, mass speculator behaviour affects the dependence structure of currency returns. We propose a rigorous statistical modelling approach using two complementary techniques in order to demonstrate that speculative carry trade volumes are informative in both the covariance and tail dependence of high and low interest rate currency returns, whereas the price based factors previously suggested in the literature hold little explanatory power. We add a new feature to the understanding of the link between the UIP condition and the carry trade strategy, specifically attributed to the large joint exchange rate movements in high and low risk environments.The appendices for this paper are available at the following URL: "http://ssrn.com/abstract=2638103" http://ssrn.com/abstract=2638103.

Ex-post deviations from uncovered interest parity (UIP) – realized differences between dollar returns on identical assets of different currencies – equal the real interest differential plus real exchange rate growth. Among industrialized countries, UIP deviations are largely explained by unanticipated real exchange rate growth, but among developing countries, real interest differentials are “where the action is.” This observation is due to the greater variability of inflation in developing countries, but may also stem from higher and more variable risks and capital controls in these countries. Also, among developing countries with moderate inflation, offsetting comovements of real interest differentials and real exchange growth support the sticky-price hypothesis.