Investor's wiki



Life's meaning could be a little more obvious.

The term half-life alludes to the place where half of the total principal of a debt obligation comes due or has been paid off. Otherwise called the average life, the half-life permits borrowers to determine the place where they have completely paid half the principal.

The half-life of a debt vehicle is generally determined in the contract between the lender and borrower. It may not really be the specific halfway point of the repayment period as factors, for example, interest rates and amortization schedule, influence the time period.

Seeing Half-Life

The two parts to a debt obligation regularly incorporate the principal balance and interest. The principal is the total amount borrowed and interest is the cost of borrowing communicated as a percentage rate. At the beginning, the majority of the payments go toward interest. Be that as it may, over the long haul, a greater amount of the payments are applied to the principal balance.

The half-life is the place where half of the principal balance of the debt is completely paid. This applies to loans, mortgages, different corporate or municipal issued bonds, and different assets like mortgage-backed securities.

In real estate, half-life implies the halfway point of mortgage repayment. Bonds that are outside of the mortgage realm have a half-life that is dependent on repayment through amortization or a sinking fund provision.

In mortgage-backed securities, home loans are sold by issuing banks to financial companies or government-sponsored enterprises, like Fannie Mae, Freddie Mac, and Ginnie Mae. These are then packaged together to form single investable securities. Half-life happens when half of the aggregate principal of all underlying mortgages is paid.

Mortgage-Backed Securities

The half-life date of a mortgage ought to regularly happen later than the ordered halfway point of the loan. In certain conditions, be that as it may, this moment can emerge much speedier. The average home mortgage term in the U.S. is 30 years, yet the average half-life of a mortgage-backed security is around 12 years. Why?

This happens in light of the fact that a few mortgages packaged into MBSs are paid ahead of schedule. Each time a homeowner makes a prepayment, it speeds up the amount of time it takes for these investments to recover half of the principal on the underlying mortgages.

Getting compensated speedier than expected is ordinarily something worth being thankful for. That is not the situation for MBS holders. At the point when homeowners refinance, investors get compensated the principal they are owed yet in addition pass up interest that was still due on the original mortgage.

This makes the job of foreseeing where interest rates are going to the MBS investor. Consistent rates ought to delay the duration of a MBS and consequently the length of the half-life, guaranteeing more money is recovered from the investment. Rising rates are not all that ideal, however, as they frequently leave investors stayed with lower yields than they could get somewhere else.

Illustration of Half-Life

As verified over, the term half-life can be applied to quite a few debt obligations. The following are two instances of two famous forms, mortgages and bonds.


A mortgage's half-life is the halfway point of principal repayment. Due to amortization and the inclusion of interest, early payments in the loan are weighted to pay more interest than principal.

For a 30-year mortgage loan of $100,000 to purchase a home, with a 5% interest rate, expect a regularly scheduled payment of around $500. Early payments incorporated a high level of interest payment with less applied to the principal. In this scenario, the half-life won't be 15 years on a 30-year loan, yet more probable more like 19 years to pay off half the mortgage's principal.


The half-life of a bond can likewise differ. A 25-year bond might incorporate a provision where 5% of the bond's principal must be repaid following five years of the issue. In this case, the bond has a half-life of five years plus the number of years required to retire half the issue. The bond will, in this way, arrive at its half-life following 15 years.


  • Half-life addresses a date in the future when half of the total principal of a debt obligation is completely paid.
  • Interest rates and amortization schedules can influence the half-life of a debt vehicle, particularly mortgages.
  • The half-life can be determined for any form of debt, including loans, mortgages, bonds, or mortgage-backed securities.