How Interest Rates Affect Bond Prices

Since the bottom fell out of the stock market in 2008, investors have been shifting money from stocks into bond funds. Since 2007, there have been $1.39 trillion invested in Bond Funds versus $193 billion in stock funds. The most logical explanation is an attempt to find income and safety, but are bonds truly safe? To explore that question we need to understand where interest rates are now, where they will be in the future, and how changes in the interest rates will affect bonds.

Interest Rates

In response the financial crisis, the Federal Reserve (the Fed) lowered the federal funds rate to a historic low of 0% – 0.25% and they have remained there ever since. In their recent guidance, the Fed announced their intention to keep the rate at that low level until the unemployment rate falls below 6.5% which they predict will happen in 2015. The accuracy of their estimation can be argued but it really isn’t they key issue. What is important is that interest rates are as low as they will go and the next change in interest rates will be up. When that happens, bond investors may find their portfolios in trouble.

Bond Prices

The rule is simple. When interest rates go up, bond prices go down.

Suppose you buy a $1000 bond today which pays 5% interest. Every year the bond will pay $50 until the bond matures and then you receive the $1000 back. You pay $1000 for the $1000 bond. In investment terms, you just purchased the bond at Par Value.

Tomorrow, the same bond issuer raises the interest rate on new bonds to 6%. Those bonds pay $60 every year until the face amount is returned to the investor. If someone else is looking to buy a bond, they would obviously chose the 6% bond for their $1000 over your 5% bond… unless you were willing to sell your $1000 bond for less than $1000. At some discounted price, the 5% bond is just as attractive as the 6% bond for $1000.

Relationship between bond prices and interest rates: Why bond prices move inversely to changes in interest rate

Bond fund buyers need to be aware (or should they beware?). There is no argument that interest rates will be going up. The only unknown is when it will happen. When it does, the prices of the bonds in bond funds will fall and the fund values will go down.

Key Terms

  • Par Value – the face amount of a bond. It is what an investor paid for the bond when it was initially issued and what will be repaid to an investor when the bond matures.
  • Discount Bond – a bond which is currently trading for less than its par value.
  • Premium Bond – a bond which is currently trading for more than its par value.

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