that may be exercised at any time before, and up to, its expiration date
. European option
, in comparison, can be exercised only on its expiration date. The payoff
of an American option (like that of a European option) depends on the average price
of the underlying asset
as on a specific date and (unlike that of an Asian option) not over a period
. These option names
, however, refer only to the types of options and not to any geographical area. Also called American-style option.