What is Interest Rate Risk?
Interest rate risk is defined as the risk of change in the value of an asset as a result of volatility in interest rates. It either renders the security in question non-competitive or increases its value. Though the risk is said to arise due to an unexpected move, generally investors are concerned with downside risk.
This risk directly affects the fixed-rate security holder. Whenever the interest rate rises, the price of the fixed-income bearing security falls and vice-a-versa.
Example of Interest Rate Risk
Let us understand Interest rate risk through an example.
If an investor has invested some amount in a fixed rate the bond at the prevailing price, which offers him a coupon rate of 5% and if thereafter interest rises to 6%, then the price of the bond would decline. This is because the bond is offering a rate of 5% while the market is offering a rate of return of 6%, hence if the investor wants to sell this bond in the market, the buyer would offer him the lesser amount for the bond as this bond is low-yielding as compared to the market. By doing this, the new investor would try to earn the return similar to the market as the invested amount is less.
In other words, the opportunity cost of getting a better return elsewhere, increases with an increase in the interest rate, hence it results in a decline in bind price.
There are various ways of combating the interest rate risk. One can buy interest rate swaps, call or put options for the securities or invest in the negatively correlated securities to hedge the risk.
Impact of Interest Rate Change on Bonds
Interest rate change impacts bonds with different maturities, to a different extent. The correlation between interest rate move and a movement in the price gets stronger with the increase in maturity. This is so because, in case of a rise in interest rate, the bond with a longer maturity will suffer a lower rate of interest for a longer time as compared to a bond with shorter maturity. That’s why investing in bonds with different maturities is used as a hedging technique to combat the interest rate risk.
Interest rate change impacts coupon bonds and zero-coupon bonds differently. If we consider both types of bonds with the same maturity, we will be able to experience a sharper decline in the price of zero-coupon bond due to interest rate rise as compared to the coupon bond. This is because of the fact that the whole amount is to be received at the end of the stipulated period in case of zero-coupon bond and hence, it increases the effective duration whereas the returns are generated periodically in case of coupon bonds and hence, it reduces the effective duration of repayment.
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Interest rate risk is also impacted by the coupon rate. The bond with a lower coupon rate has higher interest rate risk as compared to a bond with a higher interest rate. This is so, as a small change in the market interest rate can easily outweigh the lower coupon rate and will reduce the market price of that bond.
Types of Interest Rate Risk
There are two types of interest rate risk:
#1 – Price Risk
It is the risk of change in the price of the security which may result in an unexpected gain or loss when the security is sold.
#2 – Reinvestment Risk
It refers to the risk of change in the interest rate which may lead to non-availability of the opportunity to reinvest in the current investment rate. It is further divided into two parts –
- #1 – Duration Risk – It refers to the risk arising from the probability of unwilling pre-payment or extension of the investment beyond the pre-determined time period.
- #2 – Basis Risk – It refers to the risk of not experiencing the exact opposite behavior to interest rate changes in the securities with inverse features.
Calculating Duration and Change in Price due to the Interest Rate Change
Duration of the security directly relates to the extent to which a change in interest rate will impact the price. It is different from maturity. It calculates the expected change in the price as a result of a 1% change in interest rates. It approximates the price elasticity of demand. It is calculated by adding the product of the time period of cash flow and the respective weights, which are calculated on the basis of the present value of cash flows.
Example
A five-year bond with a face value of $100 is issued with a coupon rate of 6%. It has semi-annually compounded market yield of 8%. Calculate duration.
Solution:
The coupon payment is done on a half-yearly basis. Hence, cash flow after every 6 months would be half of 6% i.e. $3.
Hence, the duration of this bond is 3.599 years whereas maturity is 4 years. The price of the bond is the sum total of the present value of all the cash flows, which is $93.27.
Change in price is proportional to the change in interest rate, which is calculated by using the following formula:
So, if the % increase in interest rate is 0.1%, then in the above example, the change in the price would be: -0.1% * 3.599 * 93.27 = -$0.34
New price of the bond would be = $93.27 – $0.34 = $92.93.
You can refer the above given excel template for the detailed calculation of interest rate risk.
Advantages
- Gain from favorable interest rate movements.
- Arbitrage gain by operating in multiple markets.
- Creation of an efficient market platform through the introduction of participants like insurers.
Disadvantages
- The potential loss from unexpected interest rate movements.
- Increased cost viz. hedging cost, administration cost, etc.
Conclusion
Interest rate risk is the primary driver of the markets. It has a direct impact on fixed-income bearing securities and an indirect impact on share prices. It also impacts foreign exchange rates directly. There are a lot of ways to hedge these risks and the market offering such products is highly liquid and efficient. Although, there is a cost involved for hedging interest rate risk in the form of brokerages, premium, etc. but the benefits might outweigh the costs in most of the times.
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