For the same change in interest rates, a longer term bond will
move more than a shorter term bond. The price change of a bond is
base on the duration of the bond. The formula for calculating
duration is complex. But in simple terms, the duration of a bond is
the percentage change of the price of a bond for every 1% change in
interest rates. For example, assume a 5 year Treasury bond has a
duration of 4.0 and a 10 year Treasury bond has a duration of 7.5.
If both interest rates go up one percentage point, the 5 year bond
will decrease in price by 4.0% and the 10 year bond will decrease
in price by 7.5%.