Chart 1 shows the development of market interest rates since April 1999. To the best of my knowledge, I cannot think of any precedents in financial history, either at home or abroad, where a central bank has guided short-term interest rates down to virtually zero and maintained that level for a long period.
Short-term interest rates are the key variable in the transmission mechanism of monetary policy and a central bank influences them by controlling reserves in the money market, thereby affecting various aspects of the overall economy. Thus, guiding short-term interest rates down to virtually zero means that the central bank has used its traditional policy tool to the maximum extent possible.