The main purpose of this thesis is to propose the valuation method of PX index options. PX index consists of blue chip stocks traded on Prague Stock Exchange. There are traded a few futures contracts on PX index on Prague Stock Exchange. However, the options on PX index are traded neither on Prague Stock Exchange nor on the OTC market. It is reasonable to think that it is only question of time when the trading of these options will emerge and thus, it is highly relevant subject of research to propose the method for valuation of these options. The traditional Merton's approach for valuation of equity index options assumes constant volatility and constant risk free rate. This results in serious mispricing which can be easily seen when we compare market prices and Merton formula derived prices. Instead, this thesis releases the assumptions of constant risk free rate and constant volatility. Firstly, it is assumed that that the risk free rate is time dependent function based on current market expectations and secondly it is assumed that the volatility of underlying asset follows NGARCH-mean process. For the purpose of former, the validity of pure expectation theory assumption is made. This enables to employ the instantaneous forward rate curve estimation procedure. For the purpose of the latter, the locally risk-neutral valuation relationship is applied. The assumption of NGARCH-mean process is essential in an effort to capture usually observed patterns of volatility (volatility skews) whereas the assumption of time dependent risk free rate still moves the valuation option model closer to the reality. The author derives the expected path of risk free rate and estimates the parameters of NGARCH process. Subsequently, the empirical martingale Monte Carlo simulation is used to price the PX options with different moneyness and with different times to maturity. It is shown that this proposed model results in volatility pattern which is usually observed on developed markets and the author's results are in line with similar empirical studies testing the GARCH Option Pricing Theory. The author concludes that proposed valuation method superiors original Merton's model and thus is more appropriate for primary valuation of PX options.

Can we capture the explosive nature of volatility skew observed in the market, without resorting to non-Markovian models? We show that, in terms of skew, the Heston model cannot match the market at both long and short maturities simultaneously. We introduce Abi Jaber (2019)'s Lifted Heston model and explain how to price options with it using both the cosine method and standard Monte-Carlo techniques. This allows us to back out implied volatilities and compute skew for both models, confirming that the Lifted Heston nests the standard Heston model. We then produce and analyze the skew for Lifted Heston models with a varying number N of mean reverting terms, and give an empirical study into the time complexity of increasing N. We observe a weak increase in convergence speed in the cosine method for increased N, and comment on the number of factors to implement for practical use.

Brigo與Mercurio提出了三種新的資產價格過程，分別是位移CEV過程、位移對數常態過程與混合對數常態過程。在這三種過程中，資產價格的波動度不再是一個固定的常數，而是時間與資產價格的明確函數。而由這三種過程所推導出來的歐式選擇權評價公式，將會導致隱含波動度曲線呈現傾斜曲線或是微笑曲線，且提供了參數讓我們能夠配適市場的波動度結構。本文利用台指買權來實證Brigo與Mercurio所提出的三種歐式選擇權評價公式，我們發現校準結果以混合對數常態過程優於位移CEV過程，而位移CEV過程則稍優於位移對數常態過程。因此，在實務校準時，我們建議以混合對數常態過程為台指買權的評價模型，以達到較佳的校準結果。 / Brigo and Mercurio proposed three types of asset-price dynamics which are shifted-CEV process, shifted-lognormal process and mixture-of-lognormals process respectively. In these three processes, the volatility of the asset price is no more a constant but a deterministic function of time and asset price. The European option pricing formulas derived from these three processes lead respectively to skew and smile in the term structure of implied volatilities. Also, the pricing formula provides several parameters for fitting the market volatility term structure. The thesis applies Taiwan’s call option to verifying these three pricing formulas proposed by Brigo and Mercurio. We find that the calibration result of mixture-of-lognormals process is better than the result of shifted-CEV process and the calibration result of shifted-CEV process is a little better than the result of shifted-lognormal process. Therefore, we recommend applying the pricing formula derived from mixture-of-lognormals process to getting a better calibration.