In an expansionary foreign exchange operation the authority buys foreign
bonds from private investors when
*
a dB , change in the foreign bond holdings by
the authority is positive; so is dM , change in money supply, i.e., the monetary
base is expanding. At the same time, the foreign bond holdings by private investors,
*
a dB , fall. The effect of this operation is demonstrated in Figure 10.8. The
MM line shifts right-downwards to M’M’ and the B*
B*
line shifts right-upwards
to B*
’B*
’, with the directions of the movements being suggested by the illustrations in Figure 10.2 and Figure 10.4. The new general equilibrium is settled down
at point E’ with an increased exchange rate of ' S and a reduced interest rate of
' r . Accompanied by these shifts are the fall of the interest rate and the depreciation of the domestic currency. Compared with an expansionary open market operation, the degree of the depreciation of the domestic currency is larger and that
of the fall in the interest rate is smaller. The increase in the monetary base and the
shortage in foreign bonds caused by the purchase by the authority lead to rising
demand for foreign bonds, so foreign bond prices rise in terms of the domestic
currency value. The domestic currency depreciates or the exchange rate increases
while the demand for foreign bonds, as well as foreign bond prices in terms of the
domestic currency value, rises. The interest rate falls while money in circulation is
in excess. The BB line is unchanged since this open market operation in foreign
exchange is between money and foreign bonds, involving no changes in domestic
bonds.