Duration (vertical axis) changes quickest over yields (horizontal axis) near a callable bond’s coupon rate
The chart shows how duration changes as yield rises. X-axis shows the prevailing yield ranging from 1% to 8%, and Y-axis shows the duration ranging from 7 years to 16 years. Duration remains close to constant (at 8 years) until the yield is between 1% and 4%, rises dramatically from 8.5 years to 15 years when the yield rises from 4% to 6%, and plateaus around 16 years beyond 6% in yield.