Leaning Against the Wind: Do Central Banks Necessarily Lose?

A leaning-against-the wind intervention that has only a temporary effect on the exchange rate and that is not too aggressive can be shown analytically to yield positive expected profits to a central bank even when the exchange-rate process is non-stationary. These profits arise if there are some transitory shocks to the exchange rate. Furthermore, very aggressive intervention will yeild positive expected profits eventually when there is a tendency for exchange rates to return to a long-run equilibrium level