11.13 2 of3: The derivation of the Black-Scholes Differential Equation The value of the portfolio li is given by ∏=-f+ of aS The change in its value in time At is given by △I=4/O aS Options, Futures, and Other Derivatives, 4th edition@ 2000 by John C. Hull Tang Yincai, C 2003, Shanghai Normal University11.13 Options, Futures, and Other Derivatives, 4th edition © 2000 by John C. Hull Tang Yincai, © 2003, Shanghai Normal University The value of the portfolio is given by ƒ ƒ The change in its value in time is given by ƒ ƒ   D D D D = − + = − +     S S t S S 2 of 3: The Derivation of the Black-Scholes Differential Equation