The risk faced by the holder of a fixed income security when borrowers increase the rate at which they pay back the maturity value of the fixed income security. Contraction risk is a component of prepayment risk that increases as interest rates decline. This is because a decline in rates may create an incentive for the borrower to prepay all or part of the outstanding debt, which results in the life of the debt instrument being reduced. As interest rates decrease, the likelihood of prepayment increases.
A financial institution that offers a mortgage at an interest rate of 5% expects to earn interest on that investment for the life of the mortgage. However, if the interest rate declines to 3%, the borrower may refinance the loan, or accelerate payments, in order to reduce the number of years that they will have to pay interest to the investor. If the borrower refinances at a lower interest rate, the total payment period is reduced, thus introducing contraction risk.