In finance, an exotic option is a derivative which has features making it more complex than commonly traded products (vanilla options). These products are usually traded over-the-counter (OTC), or are embedded in structured notes.
Consider an equity index. A straight call or put, either American or European would be considered non-exotic (vanilla). An exotic product could have one or more of the following features:
The payoff at maturity depends not just on the value of the underlying index at maturity, but at its value at several times during the contract's life (it could be an Asian option depending on some average, a lookback option depending on the maximum or minimum, a barrier option which ceases to exist if a certain level is reached or not reached by the underlying, a digital option, peroni options, range options, etc.)
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Kyprianou, Andreas E.; Wim Schoutens, Paul Wilmott (2005). Exotic Option Pricing and Advanced Levy Models. Hoboken, NJ: John Wiley & Sons. ISBN 0-470-01684-1.
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