General BlackScholes Equation Assume a portfolio t = tSt + tBt consisting of t units of a

General Black–Scholes Equation Assume a portfolio

Πt = αtSt + βtBt consisting of αt units of a stock St and βt units of a bond Bt, which obey dSt = μ(St,t)dt + σ(St,t)dWt dBt = r(t)Bt dt