Using a broad data set of 20 US dollar exchange rates and order flow of institutional investors over 14 years, we construct a measure of global liquidity risk in the foreign exchange (FX) market. Our FX liquidity measure may be seen as the analog of the well-known Pastor–Stambaugh liquidity measure for the US stock market. We show that this measure has reasonable properties, and that there is a strong common component in liquidity across currencies. Finally, we provide evidence that liquidity risk is priced in the cross-section of currency returns, and estimate the liquidity risk premium in the FX market around 4.7 percent per annum.