Jose Garcia Zarate: The long period of historically low interest rates in the U.S. and the U.K. seems to be coming to an end. Increasingly, we are hearing from central bankers that normalization of rates is high on the cards.
The value of fixed income holdings is strongly exposed to changes in interest rates. Rising interest rates drive bond prices lower while falling interest rates drive bond prices higher. Duration is the measure of sensitivity of fixed income assets to changes in interest rates. It is expressed in the number of years. The bigger the number, the greater the sensitivity to an interest change.
From that we can calculate other measures of duration such as modified duration which is expressed in percentage terms, measures the change, the percentage change, in a bond price or value in response to a 1% change in interest rates.
Essentially, fixed income should be part of a well-diversified investment portfolio at all times. However, on deciding how much to allocate you must really make sure that bond duration is in keeping with the monetary policy outlook. So, for example, if you expect interest rates to go up then you'd be better off holding fixed income assets with short durations because the price would fall proportionately less than the price of assets with long durations.
Conversely, if you expect interest rates to come down, you really want to increase duration of the bond holdings in your portfolio in order to maximize the potential for capital appreciation.