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The hedge between mortgage pass-through securities and Treasury bond futures contracts is
referred to as cross hedging. There is risk involved with a cross hedge. The key to minimizing
this is to choose the right hedge ratio. The hedge ratio depends on volatility weighting, or
weighting by relative changes in value. The purpose of a hedge is to use gains or losses from
a futures position to offset any difference between the target sale price and the actual sale price
of the asset. Accordingly, the hedge ratio is chosen with the intention of matching the volatility
(i.e., the dollar change) of the futures contract to the volatility of the asset.
25. The following excerpt appeared in the following article, “Duration,” in the November 16,
1992, issue of Derivatives Week, p. 9:
“TSA Capital Management in Los Angeles must determine duration of the futures contract it
uses in order to match it with the dollar duration of the underlying, explains David Depew,
principal and head of trading at the firm. Futures duration will be based on the duration of
the underlying bond most likely to be delivered against the contract …”
Answer the below questions.
(a) Explain why it is necessary to know the dollar duration of the underlying in order to
hedge.
Knowing the dollar duration of the underlying is necessary to hedging if the hedging instrument
is to offset any loss through ownership of the asset. For example, consider hedging with futures
where the bond to be hedged is not identical to the bond underlying the futures contract. This
type of hedge is a cross hedge. The key to minimizing risk in a cross hedge is to choose the right
hedge ratio. The hedge ratio depends on volatility weighting, or weighting by relative changes in
value. The purpose of a hedge is to use gains or losses from a futures position to offset any
difference between the target sale price and the actual sale price of the asset. Accordingly, the
hedge ratio is chosen with the intention of matching the volatility (i.e., the dollar change) of the
futures contract to the volatility of the asset.
If the two bonds have the same dollar duration then their percentage change in price is the same.
This implies they will have the same dollar price volatility. By having the same dollar duration,
the bonds will have the same price change for a given change in yield and thus achieving the
hedging purpose of offsetting any loss or gain.
(b) Why can the price value of basis point be used instead of the dollar duration?