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IEOR 4706: Homework
1. European pricing. Given a standard Black-Scholes model. Fix the time of maturity T and consider the following European type of options whose payo↵ is K if S(T ) A; the payo↵ is K + A S(T ) if A < S(T ) < K + A, and the payo↵ is 0 if S(T ) > K + A. Determine the arbitrage free price of this contract. 2. Pricing a forward. Assume that the market contains one single risky asset with price process governed by the Black-Scholes model dSt = µStdt+ StdBt, and the interest rate r is constant. There is a forward contract on the risky asset with maturity T 0 > 0. What is the price of a European call option on the forward contract, with maturity T < T 0 and strike K ? 3. Implied volatility. Recall the expression of the Black-Scholes formula from Theorem 5.5 in the lecture notes. We write the European call option price CBS() as a function of the volatility . (a) Compute dCBS/d. What is the range of ! CBS()? Justify the implied volatility model. (b) Compute d2CBS/d2. On which domain is ! CBS() convex? Plot the graph of ! CBS(). (c) Provide an algorithm to compute the implied volatility given the market price Cmkt(t). Explain your choice of the parameters in the algorithm. 4. Feynman-Kac. Show that the solution to the PDE @v @t r(t, x)v + µ(t, x)@v @x + 1 2 2(t, x) @2v @x2 = 0 can be written as v(t, x) = E ⇣ e R T t r(s,Xs)dsG(XT )|Xt = x ⌘ . Hint: Apply Itoˆ’s formula to f(u,Xu) = e R u t r(s,Xs)dsv(u,Xu) (t fixed). 5. Dividend. Given a Black-Scholes financial market. Consider an underlying asset S paying a continuous stream of dividend (St, t 0) for some given constant rate > 0. (a) Show that the position of the security holder at time t is Stet. Hint: the holder of the option can immediately re-invest the dividend into the asset. (b) Compute in closed-form the call option price of this asset with continuous dividend.