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An
Asian option
(also called an average option)
is an option whose
payoff is linked to the average value of the
underlier on a specific
set of dates during the life of
the option. There are two basic forms:
An
average rate option
(or average price option) is
a cash-settled option whose payoff is based on the difference
between a the average value of the underlier during the life of the option
and a fixed strike.
An
average strike option is
a cash settled or physically settled option. It is structured like a
vanilla option except that its strike is
set equal to the average value of the underlier over the life of the option.
Both forms can be structured as
puts or calls.
Exercise is generally European, but it is possible to specify early exercise
provisions based upon an average-to-date. Averages can be calculated
arithmetically:
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or geometrically:
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They can also be weighted with some weights wi:
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The name "Asian" option has no particular
significance. David Spaughton tells the story of how both he and Mark
Standish were both working for Bankers Trust in 1987. They were in Tokyo on
business when they developed the first commercially used pricing formula for
options linked to the average price of crude oil. Because they were in Asia, they
called the options "Asian options." (see Falloon and Turner (1999))
End-users of
commodities or energies tend to be exposed to average prices over time, so Asian
options are attractive for them. Asian options are also popular with
corporations, such as exporters, who have ongoing currency exposures. Asian
options are also attractive because they tend to
be less expensive—sell at lower
premiums—than comparable vanilla puts or calls. This is because the
volatility in the average value of an underlier tends to be lower than the
volatility of the value of the underlier. Also, in situations where the
underlier is thinly traded or there is the potential for its price to be
manipulated, an Asian option offers some protection. It is more difficult to
manipulate the average value of an underlier over an extended period of time
than it is to manipulate it just at the expiration of an option.
Exact analytic formulas for average rate options
don't exist. This is primarily due to the fact that the arithmetic average of a
set of lognormal random variables has a distribution that is largely
intractable. Analytic approximations have been proposed by: Turnbull and Wakeman
(1991), Levy (1992) and Curran (1992).
If the underlier is assumed lognormal, then its geometric average is lognormal.
In a classic paper, Kemna and Vorst (1990)
use this fact to derive an analytic solution for the price of a geometric
average rate option. They use that solution as a
control variate for a
Monte
Carlo solution for the price of an arithmetic average rate option. See also Wilmott, Dewynne and Howison (2000)
and Seydel (2002) for
numerical solutions based on exact differential equations. Tavella and Randell (2000)
focus specifically on finite differences. Klassen (2001)
discusses the use of binomial methods.
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barrier option A path-dependent option
that terminates or is activated by the underlier reaching some
"barrier" level.
binary
option A type of option which features a
discontinuous expiration value.
derivative
instrument An instrument
which derives its value from the value of other financial
instruments. Article includes a list of vanilla and exotic derivatives.
lookback option
A path dependent option whose
payout depends upon the maximum or minimum underlier value
achieved during the entire life of the option.
option pricing theory The
body of financial theory used by financial engineers to value options and other
derivative instruments.
path
dependence A property of certain exotic options whose terminal value depends
upon the path taken by the underlier during the life of the option. |
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Bryis et al (1998)
describes classic pricing methodologies. Taleb (1996)
discusses the hedging of Asian Options positions. Das (2004)
provides an in-depth discussion of Asians. Seydel (2004)
provides a modern perspective on Asian pricing.
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Ads by Contingency Analysis
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Curran,
Michael (1992). “Beyond average intelligence”, Risk 5 (10), 60.
Falloon, William
and David Turner (1999). The evolution of a market, Managing
Energy Price Risk, London: Risk Books.
Kemna,
A. G. Z. and A. C. F. Vorst (1990). A pricing method for options
based on average asset values, Journal of Banking and Finance,
14, 113-129.
Klassen,
T. R. (2001). Simple, fast, and flexible pricing of Asian options,
Journal of Computational Finance, 4, 89-124.
Levy, Edmond (1992).
Pricing European average rate currency options. Journal of
International Money and Finance, 14, 474-491.
Turnbull, S. M.
and L. M. Wakeman (1991). A quick algorithm for pricing European
average options, Journal of Financial and Quantitative Finance,
26, 377-389.
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