An Asian option or average value option is a special type of option contract. For Asian options the payoff is determined by the average underlying price over some pre-set period of time. This the value of an asian option different from the case of the usual European option and American optionwhere the payoff of the option contract depends on the price of the underlying instrument at exercise; Asian options are thus one of the basic forms of exotic options. In general they do not differ in definition, only in how the pay-off is calculated. Because of the averaging feature, Asian options reduce the volatility inherent in the option; therefore, Asian options are typically cheaper than European or American options. In the s Mark Standish the value of an asian option with the London-based Bankers Trust working on fixed income derivatives and proprietary arbitrage trading.