Baaquie applies path integrals to several exotic options and presents analytical results comparing his results to the results of Black–Scholes–Merton equation showing that they are very similar. Edward Piotrowski et al. take a different approach by changing the Black–Scholes–Merton assumption regarding the behavior of the stock underlying the option. Instead of assuming it follows a Wiener–Bachelier process, they assume that it follows an Ornstein–Uhlenbeck process. With this new assumption in place, they derive a quantum finance model as well as a European call option formula.