American option

This one is not written up yet

The definition above is the short version. A full explanation — how it works, a worked example and the exam traps — is still being written. In the meantime the chapter below covers it in context.

Written up from the same chapter

• AssignmentThe allocation of exercised options to one or more option sellers — the moment the writer's obligation becomes a real cash outflow, decided by the exchange and not by the writer.
• At-the-moneyAn option whose strike price is closest to the spot price, so exercising it immediately would produce neither a gain nor a loss — the strike where the whole premium is time value and uncertainty peaks.
• Binomial pricing modelAn option pricing model that maps the underlying's possible prices as a tree of up and down moves at equally spaced time steps — accurate and flexible because it is iterative, but slow to compute.
• Break-even pointThe level of the underlying at which a position makes neither profit nor loss — for a bought call, strike plus premium; for a bought put, strike minus premium.
• Call optionA contract giving its buyer the right, but never the obligation, to buy the underlying at a fixed strike price — so the loss is capped at the premium and the gain is not.
• Close to the moneyThe band of option strikes clustered around the at-the-money strike which, in Options on Goods, lapse unless the buyer gives an explicit instruction to exercise them.