What is Convexity?
27.4 Calculation of change in price for change in yields based on duration works only for small changes in prices. This is because the relationship between bond price and yield is not strictly linear i.e., the unit change in price of the bond is not proportionate to unit change in yield. Over large variations in prices, the relationship is curvilinear i.e., the change in bond price is either less than or more than proportionate to the change in yields. This is measured by a concept called convexity, which is the change in duration of a bond per unit change in the yield of the bond.
