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Financial Engineering. Zvi Wiener mswiener@mscc.huji.ac.il 02-588-3049. Elementary Stochastic Calculus. Following Paul Wilmott, Introduces Quantitative Finance Chapter 7. Coin Tossing. R i = -1 or 1 with probability 50% E[R i ] = 0 E[R i 2 ] = 1 E[R i R j ] = 0 Define. Coin Tossing.
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Financial Engineering Zvi Wiener mswiener@mscc.huji.ac.il 02-588-3049 http://pluto.mscc.huji.ac.il/~mswiener/zvi.html
Elementary Stochastic Calculus Following Paul Wilmott, Introduces Quantitative Finance Chapter 7 http://pluto.mscc.huji.ac.il/~mswiener/zvi.html
Coin Tossing • Ri = -1 or 1 with probability 50% • E[Ri] = 0 • E[Ri2] = 1 • E[Ri Rj] = 0 • Define FE-Wilmott-IntroQF Ch7
Coin Tossing FE-Wilmott-IntroQF Ch7
Markov Property • No memory except of the current state. • Transition matrix defines the whole dynamic. FE-Wilmott-IntroQF Ch7
The Martingale Property • Some technical conditions are required as well. FE-Wilmott-IntroQF Ch7
Quadratic Variation • For example of a fair coin toss it is = i FE-Wilmott-IntroQF Ch7
Brownian Motion FE-Wilmott-IntroQF Ch7
Brownian Motion • Finiteness – does not diverge • Continuity • Markov • Martingale • Quadratic variation is t • Normality: X(ti) – X(ti-1) ~ N(0, ti-ti-1) FE-Wilmott-IntroQF Ch7
Stochastic Integration FE-Wilmott-IntroQF Ch7
Stochastic Differential Equations dX has 0 mean and standard deviation FE-Wilmott-IntroQF Ch7
Stochastic Differential Equations FE-Wilmott-IntroQF Ch7
Simulating Markov Process • The Wiener process The Generalized Wiener process The Ito process FE-Wilmott-IntroQF Ch7
value time FE-Wilmott-IntroQF Ch7
Ito’s Lemma • dt dX • dt 0 0 • dX 0 dt FE-Wilmott-IntroQF Ch7
Arithmetic Brownian Motion • At time 0 we know that S(t) is distributed normally with mean S(0)+t and variance 2t. FE-Wilmott-IntroQF Ch7
S time Arithmetic BMdS = dt + dX FE-Wilmott-IntroQF Ch7
The Geometric Brownian Motion Used for stock prices, exchange rates. is the expected price appreciation: = total - q. S follows a lognormal distribution. FE-Wilmott-IntroQF Ch7
The Geometric Brownian Motion FE-Wilmott-IntroQF Ch7
The Geometric Brownian Motion FE-Wilmott-IntroQF Ch7
S time Geometric BMdS = Sdt + SdX FE-Wilmott-IntroQF Ch7
The Geometric Brownian Motion FE-Wilmott-IntroQF Ch7
Mean-Reverting Processes FE-Wilmott-IntroQF Ch7
Mean-Reverting Processes FE-Wilmott-IntroQF Ch7
Speed of mean reversion Long term mean Simulating Yields • GBM processes are widely used for stock prices and currencies (not interest rates). A typical model of interest rates dynamics: FE-Wilmott-IntroQF Ch7
Simulating Yields • = 0 - Vasicek model, changes are normally distr. • = 1 - lognormal model, RiskMetrics. • = 0.5 - Cox, Ingersoll, Ross model (CIR). FE-Wilmott-IntroQF Ch7
Mean Reverting ProcessdS = (-S)dt + SdX S time FE-Wilmott-IntroQF Ch7
Other models • Ho-Lee term-structure model • HJM (Heath, Jarrow, Morton) is based on forward rates - no-arbitrage type. • Hull-White model: FE-Wilmott-IntroQF Ch7
Home Assignment • Read chapter 7 in Wilmott. • Follow Excel files coming with the book. FE-Wilmott-IntroQF Ch7