Suppose the interest rate increases from 10% to 12%. The effects
on the long (lease) and short (T-Bond futures) positions are as
follows:
Lease Receipts T–Bond Futures Asset – Liabilities
Value at r = 10% $85.136M $85.136M $0.000M
Value at r = 12% $74.694M $74.588M $0.106M
Change in value $10.442M $10.548M $0.106M
When interest rate increases to 12%, your firm loses on the lease
agreement, which falls in value by $10.442M to $74.694M. The
value of the futures contracts obligation also decreases (by
$10.548M to $74.588M). The value of your firm’s net position
actually increases by $0.106M. In terms of reducing risk, the
change in value on the net position ($0.106M) is substantially
smaller than the change in value of the unhedged position
($10.442M).
This example was not a perfect hedge for two reasons. First, the
duration of the lease and T-bond futures contracts were not
identical. Second, matching duration only provides a perfect hedge
if the change in interest rate is infinitesimal and the yield curve is
flat.
The duration of the lease and the T-bond also change when interest
rate changes. The new duration for the lease is 7.020 years and for
the T-bond it is 7.185 years when interest rate is 12%. Notice that
the difference in duration widens at the new interest rate. To
minimize the exposure of the net position, you can close the
existing futures contract and sell $74.694M of new futures
contracts of 12% T-Bond with duration = 6.938 years. To hedge
interest rate risk effectively you must rebalance your positions
when the interest rate changes.
Lecture Tip: Duration and Hedging
1. Duration and the Yield Curve
Ideally, the yield curve is based on pure discount bonds. The term
structure of interest rates refers to the current spot rates of interest
on pure discount bonds that differ only in their maturity. In
practice, the difficulty lies in inferring the term structure of pure
discount bonds from the available selection of coupon–bearing
bonds. Duration provides a surrogate for the maturity of a pure
discount bond because the duration of a pure discount bond is its
maturity.
2. The Effectiveness of Hedging Risk using Duration Matching