Nowadays, financial derivatives play an increasingly important role in the global financial system, and options are popular structural financial derivatives, which attract much attention from academia and the industry. China Financial Futures Exchange (CFFEX) initiated the CSI 1000 index future and CSI 1000 index option in the Chinese market on July 22, 2022, which indicates a trend of acceleration in financial innovations in China’s financial market. This dissertation focuses on the volatility models in option pricing and modern numerical procedures that approximate option prices. In this dissertation, different stochastic volatility models, for example, the Black–Scholes model and the Heston stochastic volatility model, are introduced and applied to price in not only European options but also exotic options, which possess complicated payoff structures. Moreover, a comprehensive empirical analysis is conducted to demonstrate these option pricing algorithms based on the recent data of CSI 1000 index options in the Chinese market. / Business Administration/Finance

自1980年代後期Hull & White、Wiggins、Johnson & Shanno等人相繼發表關於隨機波動度模型的文獻後，就有諸多的文獻對於在選擇權定價中考慮隨機波動度作更深入的分析與模型探討，然而關於隨機波動度的研究，在早期大多採用蒙地卡羅模擬法來分析選擇權的價格行為，但蒙地卡羅模擬法受限於運算效率不高與缺乏彈性，故在評價新奇選擇權，如美式選擇權、障礙選擇權時，並無法應用。故本文以Leisen（2000）的二元樹狀模型出發，探討在不同相關係數及參數設定下之各類選擇權的定價、避險參數及隱含波動度曲面模擬計算等主題。 最後我們得到下面幾點結論： 1.在收斂速度與運算效率方面，我們可以發現二元樹狀模型在分割期數n大於20時，計算價格與收斂價格的差距就非常微小，而若我們計算不同切割期數的最大價格差異也會發現其實都不到百分之一，因此整體而言，收斂速度是令人非常滿意的。 2.當期初波動度提高時，會縮小價外選擇權與B-S價格之間的價格誤差。當到期期限增加時，隱含波動度曲線會有整體提高的趨勢。 3.若提高波動係數σ為2.5時，則不論相關係數的正負情形，價內外的程度，皆會大幅提高選擇權的隱含波動度。而在相關係數為-0.5的時候，可以發現實證中常觀察到的隱含波動度微笑曲線，這可能代表著市場上的波動係數比我們預期中的都還來的高。 4.在進行不同相關係數及不同價內外程度下二元樹狀與單元樹狀模型的美式選擇權價格比較時，我們可以發現，若以二元樹狀模型為正確價格，當相關係數為負的時候，在價外的時候，單元樹狀模型有價格低估的現象，在價內的時候，則有價格高估的現象，而在相關係數為正的時候，則反之。 5.Leisen二元樹狀與封閉解的歐式向上出局賣權價格比較，在特定的參數設定之下，Leisen二元樹狀模型在評價歐式向上出局賣權的時候，當相關係數為負的時候，在價外的時候，模型價格會高於封閉解，在價內的時候，模型價格則會低於封閉解，而在相關係數為正的時候，則反之。

本篇論文驗證SABR模型與SABR-LMM模型的動態設定與市場選擇權價格下標的未來價格之隱含分配是否一致，判斷準則為SABR模型與SABR-LMM模型校準出的參數是否符合市場直覺。根據實證結果答案是肯定的，所以在SABR模型與SABR-LMM模型下評價選擇權不需要再做任何的主觀判斷或調整。此外本篇論文對於SABR模型與SABR-LMM模型的參數校準方法做了詳細的分析，並且清楚的閳述SABR模型與SABR-LMM模型的模型直覺。

由於一般投資人在買進或賣出選擇權時，並不會同時買進多個履約價的選擇權，故會造成選擇權隱含波動度的微笑曲線出現有不連續的現象。本文嘗試運用台指選擇權建構一個日內的隱含波動度微笑曲線交易策略，利用曲線配適的方法來捕捉瞬間時點下隱含波動度曲線發生不連續的現象，雖然最後出來的損益並不如預期但還是驗證了台指選擇權市場有多次這種不連續的機會且價格失衡的狀態會回歸正常。 / Option’s implied volatility smile curves discontinuous phenomenon exists when general investors buy or sell options, they won’t buy in every strike’s options. This paper attempts to use Taiwan Index Options (trading code: TXO) to construct a trading strategy based on the implied volatility. We use curve fitting method to capture volatility smile curve’s instant discontinuous. Although we find out that the strategy won’t make a profit, there were several times when TXO market’s implied volatility smile curves were discontinuous, and the market option price will eventually go back to the theoretical price.

Optimisation des modèles d'évaluation et de couverture d'options financières sous contraintes de liquidité / Optimization of pricing and hedging models for financial options under liquidity constraints

[pt] O presente trabalho busca explorar a previsibilidade na dinâmica temporal em modelos lineares de superfícies de volatilidade implícita estimados para opções de compra de ações brasileiras. Resultados de estudos anteriores, sob a abordagem usualmente empregada de estimação de modelos lineares em função do preço de exercício e do tempo até o vencimento a partir de dados de corte transversal sobre cada contrato disponível em dado instante, como Dumas, Fleming e Whaley (1998), revelam grande instabilidade nos coeficientes estimados ao longo do tempo. Por conseguinte, a incapacidade desta perspectiva em descrever a dinâmica intertemporal da estrutura, contrariando a observação empírica de volatilidade variável no tempo. A partir destas evidências e das conclusões de Heston e Nandi (2000), que reportaram significativa dependência da trajetória para a volatilidade dos retornos do índice S&P 500, Gonçalves e Guidolim (2006), propuseram um modelo em dois estágios, que aplica vetores autoregressivos para capturar a presença de variação temporal dos coeficientes de um modelo linear. A contribuição deste trabalho está em aplicar o Modelo proposto à realidade do mercado brasileiro de opções de ações, incipiente em liquidez e horizonte de negociação se comparado ao mercado norte americano, adaptando critérios a fim de validar sua aplicabilidade neste contexto em termos estatísticos e econômicos. Os resultados comprovam a superioridade desta abordagem em relação a outras comparáveis na literatura, mas não a capacidade de gerar retornos acima da média na presença de custos de transação contra a referência natural da taxa livre de risco. O que sugere a adequação à hipótese de eficiência de mercado. / [en] O The present study aims to explore predictability in temporal dynamics regarding linear models of the implied volatility surfaces estimated for Brazilian stocks options. Previous results, by usual approach of fitting linear models linking implied volatility to time to maturity and moneyness, available for each cross-section of option contracts at a point in time, as in Dumas, Fleming and Whaley (1998), suggest that estimated parameters of such models are highly unstable over time. Therefore, this approach isn t capable of replicating various IVS s shapes, contrary to the empirical evidence of implied volatility varying with options strike price and date of expiration. Based on these evidences and in Heston and Nandi (2000), that exploit the information on path-dependency in volatility contained in the spot S&P 500 index, Gonçalves e Guidolim (2006) proposed a two-stage approach to modeling and forecasting the S&P 500 index options IVS. In the second-stage they model the dynamics of the cross-sectional first-stage coefficients by means of vector autoregression models. The contribution of this work is to apply the proposed model to the reality of the Brazilian stock options, incipient in terms of liquidity and trading horizon dimensions when compared to the U.S. market, adapting criterians to validate its applicability in this context in statistical and economical sense. The results demonstrate the superiority of this approach over comparable literature, but not the ability to generate abnormal profits in the presence of transaction costs in excess of the benchmark of the risk-free rate. This indicates adaptation to the market efficiency hypothesis.

In this thesis, we study the quadratic rough Heston model and the corresponding simulation methods. We calibrate the model using real-world market data. We compare and implement the three commonly used schemes (Hybrid, Multifactor, and Multifactor hybrid). We calibrate the model using real-world market SPX data. To speed up calibration, we apply quasi-Monte Carlo methods. We study the effect of the various calibration parameters on the volatility smile.

本篇論文分為兩個部份。第一部份驗證隨機波動度SABR 模型以臺灣證券交易所發行量加權股價指數選擇權為驗證產品所描繪出來的波動度微笑曲線，分析其特色與值得關注的地方。由於長期以來研究者所使用的Black模型評價選擇權公式無法衡量波動度風險；雖然局部波動度模型(Local Volatility Models)能描繪出波動度所形成的波動度微笑曲線(Volatility Smile)，其動態走勢卻與標的資產價格相反，兩模型皆與真實情形不符，唯以SABR模型能順利的解決以上問題。 第二部份討論結構型商品。此部份以中國招商銀行發行的股權連結型商品作為範例，進行商品的拆解及評價，並分析其潛在風險，加以進行不同經濟情勢下的情境分析。評價個案為「掛勾香港地產股票人民幣理財計畫產品」，由於此商品連結標的達四個且有提前到期事件，並沒有封閉解。必須以風險中立下股價的動態過程模擬股價，使用蒙地卡羅模擬法來逼近合理價格。此外，亦針對評價結果進行避險參數及收益分析。

本篇論文共分為兩部分，第一部份是以每年交易量非常大的外匯選擇權（FX Option）市場以及台指選擇權為例，以Brigo 及Mercurio這兩位學者於2000年提出的Lognormal Mixture model (簡稱LM model)為基礎，捕捉選擇權市場中典型的波動度微笑（Volatility smile）曲線之特性。第二部份係商品評價之應用，是以大陸地區發行的匯率連動結構型商品（Structure Notes）為主。 第一部份中我們分別採用LM 模型（Lognormal Mixture Model）、Shifting LM模型（Shifting Lognormal Mixture Model）及LMDM模型（Lognormal Mixture with Different Mean Model）等三種模型，用以衡量其實際上在外匯選擇權市場及台指選擇權中波動微笑曲線校準的準確性。結果顯示LM模型、Shifting LM模型及LMDM模型均能有效地反應並捕捉出選擇權市場中波動度微笑曲線之特性，而其中又以LMDM模型的效果最佳，其無論在波動度校準或是選擇權價格評價上的誤差均最小。 第二部分是以「中國銀行匯聚寶0709G掛鉤美元兌加元匯率之加元產品」的匯率連動結構型商品為例，以Garman and Kohlhagen（1983）外匯選擇權模型求出其封閉解並作發行商期初利潤分析，然後再用蒙地卡羅模擬法進行投資人期末報酬分析。此外，亦針對此種商品的敏感性與避險參數作分析。

Apresentamos duas abordagens para obter uma densidade de probabilidades para o preço futuro de um ativo: uma densidade preditiva, baseada em um modelo Bayesiano para série de tempo e uma densidade implícita, baseada na fórmula de precificação de opções de Black & Scholes. Considerando o modelo de Black & Scholes, derivamos as condições necessárias para obter a densidade implícita do preço do ativo na data de vencimento. Baseando-­se nas densidades de previsão, comparamos o modelo implícito com a abordagem histórica do modelo Bayesiano. A partir destas densidades, calculamos probabilidades de ordem e tomamos decisões de vender/comprar um ativo. Como exemplo, apresentamos como utilizar estas distribuições para construir uma fórmula de precificação. / We present two different approaches to obtain a probability density function for the stocks future price: a predictive distribution, based on a Bayesian time series model, and the implied distribution, based on Black & Scholes option pricing formula. Considering the Black & Scholes model, we derive the necessary conditions to obtain the implied distribution of the stock price on the exercise date. Based on predictive densities, we compare the market implied model (Black & Scholes) with a historical based approach (Bayesian time series model). After obtaining the density functions, it is simple to evaluate probabilities of one being bigger than the other and to make a decision of selling/buying a stock. Also, as an example, we present how to use these distributions to build an option pricing formula.