Does Incomplete Spanning in International Financial Markets Help to Explain Exchange Rates?

Compared to the predictions of complete market models, actual exchange rates are puzzlingly smooth and only weakly correlated with macro-economic fundamentals, suggesting that market incompleteness plays a key role in exchange rate dynamics. Incompleteness in international financial markets introduces a stochastic wedge between the growth rates of marginal utility at home and abroad, and the change in the exchange rate. We derive a preference-free upper bound on the effects of the FX wedges. Even if domestic agents can invest only in the foreign risk-free asset, incomplete spanning fails to simultaneously match the exchange rate volatility, cyclicality and the FX risk premia in the data.