In a subsequent, alternative derivation of the Black-Scholes formula, Merton
(1973b) demonstrated that their basic mode of analysis obtains even when the
interest rate is stochastic; the stock pays dividends; and the option is exercisable
prior to expiration. Moreover, it was shown that as long as the stock price
dynamics can be described by a continuous-time diffusion process whose sample
path is continuous with probability one, ’ then their arbitrage technique is still
valid. Thorp (1973) has shown that dividends and restrictions against the use of
proceeds of short-sales do not invalidate the Black-Scholes analysis. Moreover,
the introduction of dilTerentinl taxes for capital gains versus dividends or interest
payments does not change the analysis either [see Ingersoll (l975)].