UNIVERSITY COLLEGE LONDON EXAMINATION FOR INTERNAL STUDENTS MODULE CODE COMP0048 ASSESSMENT COM P0048A 7PA PATTERN MODULE NAME Financial Engineering LEVEL: Postgraduate DATE 24 April 2019 TIME 10:00 TIME ALLOWED 2 hrs 30 mins This paper is suitable for candidates who attended classes for this module in the following academic year(s): Year 2018-19 EXAMINATION PAPER CANNOT BE REMOVED FROM THE EXAM HALL. PLACE EXAM PAPER AND ALL COMPLETED SCRIPTS INSIDE THE EXAMINATION ENVELOPE Hall Instructions Standard Calculators Non-Standard Calculators TURN OVER Financial Engineering, COMP0048 (A7P) Main Summer Examination Period, 2018-19 Suitable for cohorts: 2018/19 There are FIVE questions. Marks will be awarded for FOUR questions. If more than FOUR are attempted, then only marks for the best FOUR will count. Each question is worth 25 marks. The marks avalilable for each part of each question are given in square brackets. Standard calculators are permitted. Throughout this examination Wt or W (t) is a standard Brownian motion. 1. a. [5 Marks] The moment generating function (MGF) of Y, denoted COMP0048 My ( 0) is given by the expectation provided the expectation exists. Explain how this definition can be adapted to calculate moments of different orders. b. [10 Marks] If Y is a normally distributed random variable, Y rv N (µ, 0"2 ), then show that the MGF My (0) is You are required to show all your working when evaluat ing the integral. c. [10 Marks] Consider the stochastic differential equation for the diffusion Xt. The parameters a, b are constant. Using Ito's lemma and suitable integration over [O, T], show that XT = Xo exp { (a - ½b 2) T + b¢v'T} where¢ rv N (0, 1). 1 TURNOVER 2. a. [10 Marks] COMP0048 1. Explain what happens to the number of shares and the share price when a n-m stock split is announced; you may assume n > m. Give four reasons why a company may issue a stock split? 11. Discuss dividends in the context of shares. Your discussion should include all key dates during the cycle of a dividend payment. b. [10 Marks] i. Explain what happens when you short sell some shares. 11. What is the limiting behaviour of ( r )nt lim 1 + - n----t(X) n Full working must be shown. c. [5 Marks] In the FX markets, define the terms base currency and counter currency. What is the meaning of the following quoted currency pair? EUR/USD = 1.25492 If at a later time this pair appears on another exchange as USD /EUR = 0.85543 what is the affect on EUR? 2 CONTINUED 3. a. [10 Marks] Assume that an asset price S evolves according to the SDE COMP0048 dS S = (µ - D) dt + O"dWt, where µ and O" are constants. In particular S pays out a continu ous dividend stream equal to DSdt during the infinitesimal time interval dt, where D the dividend yield is constant. Now suppose a European style derivative security is written on this asset with the properties that at expiry the holder receives the asset and prior to expiry the derivative pays a continuous cash flow C (S, t) dt during each time interval of length dt. Show that the option price satisfies the following partial differen tial equation av 1 2 2 a2v av 8t + 2(]" S as2 + (r - D) Sas - rV = -C (S, t). (3. 1) b. [15 Marks] In (3.1) suppose that the cash flow C (S, t) has the form C (S, t) = f (t) S. By writing V = ¢ (t) S and assuming a final condition at time T given by V(S,T) = S, show that the delta of the derivative security is � (S, t) = e-D(T-t) + 1 T e-D(r-t) f ( T) dT . 3 TURNOVER 4. a. Consider the pricing equation for the value of a derivative security COMP0048 V (S, t), where S 2: 0 is the spot price of the underlying equity, 0 < t::; T is the time, r 2: 0 the constant rate of interest, and O' is the constant volatility of S. The variables ( t, S) can be written as t = m6t O ::; m ::; M; S = n6S O ::; n ::; N, where (5t, 5S) are fixed step sizes in turn. V (S, t) is written dis cretely as Vnm. An Explicit Finite Difference Method is to be developed to solve ( 4.1) using a backward marching scheme. i. [6 Marks] Derive a difference equation in the form where an, bn, cn should be defined; you may use the following as a starting point, v:m _ v:m-1 av v:m v:m n n n+I - n-1 ' 8S "" 25S ; Vn""'- 1 - 2vnm + Vn+I 5S2 11. [5 Marks] Obtain expressions for the final and boundary con ditions in finite difference form for a European Call Option. b. [8 Marks] A European call option is to be priced. Outline a Monte Carlo method to do this. c. [6 Marks] Give four advantages of the Monte Carlo method for pricing derivatives 4 CONTINUED 5. a. [8 Marks] Suppose the spot interest rate r, which is a function COMP0048 of time t, satisfies the stochastic differential equation dr = u (r, t) dt + w (r, t) dWt . The Bond Pricing Equation for a security V = V (r, t; T) is av 1 2 a2v av 8t + 2w ar2 + (u - Aw) ar - r V = 0. (5.1) By considering an unhedged bond and the risk free return, explain how and why A arises. You are not required to derive (5.1) b. [17 Marks] The extended Hull and White model has risk-adjusted drift and diffusion, in turn as u -Aw = rJ ( t) --yr, w (r, t) = c, where rJ (t) is an arbitrary function of time and 'Y and care con stants. Deduce that the value of a zero coupon bond with the usual redemption value Z (r, T ; T) = 1, is given by where and A (t; T) Z (r, t; T) = exp (A (t; T) - rB (t; T)), B (t; T) = _!_ (1 - e--y(T-t)) 'Y -1 T TJ(T)B (T;T)dT + 2�2 ((T-t) + �e--y(T-t) - 2\e- 2 -y(T-t) -2�). 5 END OF PAPER
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