A
option contract to buy or sell an underling asset at strike price in
the future, a combination of call and put rolled into a single option
contract. A double option gives the holder the right either to buy or
to sell the underlying asset at the strike price. That is, there are
three choices for a double option: buy, sell, or do nothing and allow
the option to expire. Double options are traded in Europe. When one
side of the option is exercised, the opposite side is automatically
terminated.