• Average life is the average length of time it takes to pay off the outstanding principal on a debt instrument, such as a treasury bill, bond, loan, or mortgage-backed security.

  • The life expectancy calculation is useful for investors who want to compare the risk associated with different investments before making an investment decision.
  • Most investors will choose investments with a shorter average life, as this means that they will receive a return on investment faster.
  • Prepayment risk occurs when a loan borrower or bond issuer repays the principal amount of the debt ahead of schedule, which shortens the average investment term and reduces the amount of interest the investor receives.