With an expansionary sterilised foreign exchange operation, the authority purchases foreign bonds, and then almost simultaneously sells domestic bonds. The monetary base is kept unchanged while money is created and destroyed simultaneously. In a certain sense, these two opposite operations are simply a swap of domestic bonds for foreign bonds and money serves a medium for the swap. Such a swap effectively results in an excess in the demand for foreign bonds and an excess supply of domestic bonds. Corresponding to the rising demand for foreign
bonds is a rise in foreign bond prices in terms of the domestic currency value.