American Option

An American option is a contract which gives the holder the right to buy or sell the underlying asset for an agreed price up to the expiry.

American options can only be exercised at any time up to the expiry.

American Call Option
An American call option is a contract which gives the holder the right to buy the underlying asset for an agreed price up to the expiry.

American put Option
An American put option is a contract which gives the holder the right to sell the underlying asset for an agreed price up to the expiry.

American Option Valuation
There is no close-form solution for American-style option up to now (for detail , and some approximations see Black-Scholes Model for American Options). We can use binomial tree method, Monte Carlo method and others to value American options.