There are two different types of options with respect to expiration.
There is a European style option and an American style option. The European style option cannot be exercised until the expiration date. Once an investor has purchased the option, it must be held until expiration. An American style option can be exercised at any time after it is purchased.
Today, most stock options which are traded are American style options. And many index options are American style. However, there are many index options which are European style options. An investor should be aware of this when considering the purchase of an index option.
