Call options must sell for at least the stock price less the present value of the exercise price and any dividends to be paid before expiration. This implies that a call on a non-dividend-paying stock may be sold for more than the proceeds from immediate exercise. Thus, when the stock does not pay dividends until after option expiration, it will never be optimal to exercise an American call option early. In this special case, European calls are worth as much as American ones.

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