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The Limits of Mathematics and NP Estimation in ... - Chichilnisky

The Limits of Mathematics and NP Estimation in ... - Chichilnisky

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42 Advances <strong>in</strong> Econometrics - <strong>The</strong>ory <strong>and</strong> Applications12 Will-be-set-by-IN-TECH<strong>in</strong> terms <strong>of</strong> the moments <strong>of</strong> the volatility process. <strong>The</strong>ir results <strong>in</strong>dicate that the suggestedmodel outperforms the classic Black-Scholes formula. Here we extend Gong et al. (2010) <strong>and</strong>propose an option pric<strong>in</strong>g model with seasonal GARCH volatility as follows:dS t = rS t dt + σ t S t dW t (27)( ) [ ( )]StSty t = log − E log = σ t Z tS t−1 S t−1(28)θ(B)Θ(L)σ 2 t = ω + α(B)y 2 t (29)where S t is the price <strong>of</strong> the stock, r is the risk-free <strong>in</strong>terest rate, {W t } is a st<strong>and</strong>ard Brownianmotion, σ t is the time-vary<strong>in</strong>g seasonal volatility process, {Z t } is a sequence <strong>of</strong> i.i.d. r<strong>and</strong>omvariables with zero mean <strong>and</strong> unit variance <strong>and</strong> α(B), θ(B) <strong>and</strong> Θ(L) have been def<strong>in</strong>ed <strong>in</strong>(4).<strong>The</strong> price <strong>of</strong> a call option can be calculated us<strong>in</strong>g the option pric<strong>in</strong>g formula given <strong>in</strong>Gong et al. (2010). <strong>The</strong> call price is derived as a first conditional moment <strong>of</strong> a truncatedlognormal distribution under the mart<strong>in</strong>gale measure, <strong>and</strong> it is based on estimates <strong>of</strong> themoments <strong>of</strong> the GARCH process. <strong>The</strong> call price based on the Black-Scholes model withseasonal GARCH volatility is given by:C(S, T) =S(f [E(σ 2 t )] + 1 2 f ′′ [E(σ 2 t )]( 13 κ(y) − 1))E 2 (σt 2 )− Ke(g[E(σ −rT t 2 )] + 1 ( ) )2 g′′ [E(σt 2 1)]3 κ(y) − 1 E 2 (σt 2 ) , (30)where f <strong>and</strong> g are twice differentiable functions, S is the <strong>in</strong>itial value <strong>of</strong> S t , K is the strike price,T is the expiry date, σ t is a stationary process with f<strong>in</strong>ite fourth moment, <strong>and</strong> κ (y) = E(y4 t ) .[E(y 2 t )]2Also, f [E(σt 2)], g[E(σ2 t )], f ′′ [E(σt 2)],<strong>and</strong>g′′ [E(σt 2 )] are given by:⎛⎞f [E(σt 2 )] = N(d) =N ⎝ log(S/K)+rT + 1 2 E(σ2 t√) ⎠ ,E(σt 2)[ ⎛f ′′ [E(σt 2)] = √ 1 − 2π()g[E(σt 2 )] = N d −√E(σ t 2) ⎝ E(σ2 t ) − 2(log(S/K)+rT)4E(σ 2 t ) √E(σ 2 t )⎛⎞= N ⎝ log(S/K)+rT − 1 2 E(σ2 t√) ⎠ ,E(σt 2)⎞⎠( )[E(σ 2t )] 2 − 4(log(S/K)+rT) 28[E(σt 2)]2 ⎛⎞+ ⎝ 6(log(S/K)+rT) − E(σ2 t )] {}√ ⎠ × exp − (2(log(S/K)+rT)+E(σ2 t ))28[E(σt 2)]2 E(σt 2)8E(σt 2) ,

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