Rational speculation and exchange rates

Models of exchange rates have typically failed to produce results consistent with the key fact that real and nominal exchange rates move in ways not closely connected to current (or past) macroeconomic variables. Models that rely on the same shocks to drive fluctuations in macroeconomic variables and exchange rates typically imply counterfactually-strong co-movements between them. We develop a model in which new information leads agents to change their rational beliefs about risk premia on foreign exchange markets. These changes in risk premia work through asset markets to cause real and nominal exchange rates to change without corresponding changes in GDP, productivity, money supplies, and other key macro variables.