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A swaption is an
OTC
option on a
swap. Usually, the
underlying swap is a
vanilla interest rate swap.
Unless stated otherwise, that is how we will use the tem in this article.
However, the term "swaption" might be used to refer to an option on any
type of swap.
In case you are wondering why anyone would want to buy a swaption, the
answer is often that they don't want to. Frequently, they want to sell a
swaption. Consider a corporation that has issued debt in the form of
callable bonds paying a fixed
semiannual interest rate. The corporation would like to swap the debt into
floating rate debt. The corporation
enters into a
fixed-for-floating swap with a derivatives dealer. To liquidate the
call feature of the debt, it also sells the dealer a swaption. For
derivatives dealers, clients often want to sell them swaptions while other
clients want to buy caps from them. The
dealers then face the challenge of hedging the
short caps with the
long swaptions.
Swaptions can be for American,
European or
Bermudan exercise. They can be
physically settled, in
which case an option is actually entered into upon exercise. They can also
be cash settled, in
which case the market value of the underlying swap changes hands upon
exercise.
To specify a swaption, we must indicate three things:
the
expiration date of the option
the fixed
rate on the underlying swap
the tenor
(time to maturity at exercise of the option) of the swap.
The purchaser of the swaption pays an up front
premium. If
she exercises, there is no strike price
to pay. The two parties simply put on the prescribe swap. Note, however,
the fixed rate specified for the swaption plays a role very similar to
that of a strike price. The holder of the swaption will decide whether or
not to exercise based on whether
swap rates rise above or
fall below that fixed rate. For this reason, the fixed rate is often
called the strike rate.
By symmetry, a call on a pay-fixed
swap is the same thing as a put on a
receive-fixed swap. Similarly, a call on a receive fixed swap is the same
as a put on a pay fixed swap. For this reason, it is often more convenient
to speak in terms of two basic forms of swaption:
A
payer swaption is a call on a
pay-fixed swap—the swaption holder has the option to pay fixed on a swap.
A
receiver swaption is a call on a
receive fixed swap—the swaption holder has the option to receive fixed on
a swap.
Suppose a party purchases a 1x5 payer swaption struck at 5%. A year
later, if the four-year swap rate is 6%, she will exercise the swaption
and pay 5% fixed for Libor flat on a
four-year swap. If instead, the four-year swap rate is 4%, she will not
exercise the swaption.
Swaptions are priced using Black
76. For this purpose, the underlier is treated as a
forward on a swap.
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basis swap
A floating-for-floating interest rate or currency swap.
callable bond A bond which allows the issuer to repurchase the bond for a specified
price on certain dates prior to the bond's maturity.
currency
swap A swap for the exchange of cash flow streams in two
different currencies.
derivative
instrument An instrument
that derives value from the value of some commodity, energy, or other financial
instrument.
fixed income
term structure Refers collectively to a spot curve, forward curve,
discount curve, yield curve or any other curve that describes the time value of
money.
floater
A fixed income instrument whose coupon fluctuates with some designated reference
rate.
forward rate agreement
A cash-settled forward contract on a short-term loan.
interest rate
cap A derivative instrument which is linked
to interest rates.
interest rate spreads
Spreads between interest rates.
interest
rate swap A swap under which both cash flow streams are in the same currency and are defined as cash flow streams that might be associated with some fixed income obligation.
swap
An OTC derivative under which two counterparties exchange two cash
flow streams. |
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Ads by Contingency Analysis
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James and Webber (1998)
discuss swaptions from a practical financial engineering perspective. For a
comprehensive treatment, see Das (2003).
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