American call option
= American call option
{c}
{title2=$\sup_{\tau\le T}\mathbb E_Q[e^{-\int_t^\tau r_sds}(S_\tau-X)^+]$}
An American call permits purchase of the underlying at strike $X$ at a chosen <stopping time> no later than maturity. Under standard pricing and integrability hypotheses its value is the displayed <optimal stopping> value. A <European call option> restricts exercise to the final time. Dividends and interest on the deferred strike affect the incentive to exercise early.