The subject of this thesis is recent development of credit evaluation industry and analysis of rating agency`s behaviour in relation to official rating changes. In the first chapter, fundamental limitations of analytical ratings are defined. Stating both advantages and disadvantages arising mainly from market defficiency, the second one introduces credit default swap as an alternative manner for credit risk measurement. Next part summarizes existing academic activity in context of rating informatory value, highlighting abnormal and asymmetric market reactions. Based on Moodys` approach, the fouth chapter provides reader with the concept of market implied ratings that are consequently used to analyse relation between CDS-IR and official ratings. The last subchapters investigate sensitivity ratio of how rating gap level determines prospective response of rating agency.

Derivatives have a large and significant role on the financial markets today and the popularity of options has increased. This has also increased the demand of finding a suitable option pricing model, since the ground-breaking model developed by Black & Scholes (1973) have poor pricing performance. Practitioners and academics have over the years developed different models with the assumption of non-constant volatility, without reaching any conclusions regarding which model is more suitable to use. This thesis examines four different models, the first model is the Practitioners Black & Scholes model proposed by Christoffersen & Jacobs (2004b). The second model is the Heston´s (1993) continuous time stochastic volatility model, a modification of the model is also included, which is called the Strike Vector Computation suggested by Kilin (2011). The last model is the Heston & Nandi (2000) Generalized Autoregressive Conditional Heteroscedasticity type discrete model. From a practical point of view the models are evaluated, with the goal of finding the model with the best pricing performance and the most practical usage. The model´s robustness is also tested to see how the models perform in out-of-sample during a high respectively low implied volatility market. All the models are effected in the robustness test, the out-sample ability is negatively affected by a high implied volatility market. The results show that both of the stochastic volatility models have superior performances in the in-sample and out-sample analysis. The Generalized Autoregressive Conditional Heteroscedasticity type discrete model shows surprisingly poor results both in the in-sample and out-sample analysis. The results indicate that option data should be used instead of historical return data to estimate the model’s parameters. This thesis also provides an insight on why overnight-index-swap (OIS) rates should be used instead of LIBOR rates as a proxy for the risk-free rate.

Since the introduction of derivatives into the modern financial market, volatility based tradingstrategies have emerged as important tools for asset managers. Since the financial crisis apopular trading strategy has been dispersion trading, however few published studies ofdispersion trading exist. This thesis aim to perform a study of how dispersion strategies performand their characteristics. This is achieved by finding basic common dispersion trading strategies,isolate and evaluate their attributes to then draw conclusions in general about dispersion trading.Three basic dispersion strategies are found based on vanilla option spreads and their performanceis back-tested. It was found that the strategies delivered positive return with low marketcorrelation and acceptable risk. It is also found that transaction costs is a key-factors tosuccessfully use dispersion trading. Thus it is a vital factor to consider when creating adispersion based trading strategy. An interesting topic for further research is how trading signalssuch as the implied correlation and the implied volatility spread can be used to increaseprofitability. As well to model market impact from dispersion trading.

This thesis investigates the relationship between implied volatility and dividend yield in the options market, focusing on testing the Bird-in-Hand theory versus the Dividend Irrelevancy theory. Utilizing panel data analysis and regression techniques, with both ordinary and lagged regressions, the study explores how dividend yield impacts European options implied volatility across European markets over ten years from February 2013 to February 2023. Employing the Hausman specification test, Breusch Pagan multiplier test, cluster standard errors, and heteroskedasticity for robustness. The analysis includes both call and put options, incorporating various control variables and market factors. The findings reveal that changes in dividend yield consistently impact call option implied volatility and also exhibit a stronger and more consistent negative relationship with put option implied volatility, overall, supporting the Bird-in-Hand theory. Furthermore, this thesis highlights the importance of considering alternative methodologies, expanding sample sizes, and exploring additional variables to enhance understanding of option pricing dynamics.

This thesis investigates the application of the Black-Scholes model for pricing long-maturity options, primarily utilizing historical data on S\&P500 options. It compares prices computed with the Black-Scholes formula to actual market prices and critically examines the validity of the Black-Scholes model assumptions over long time frames. The assumptions mainly focused on are the constant volatility assumption, the assumption of normally distributed returns, the constant interest rate assumption and the no transaction cost assumption. The results show that the differences between computed prices and actual prices decrease as options get closer to maturity. They also show that several of the Black-Scholes model assumptions are not entirely realistic over long time frames. The conclusion of the thesis is that there are several limitations to the Black-Scholes model when it comes to pricing long-maturity options.

Seit der Nahrungsmittelpreiskrise 2007/08 ist die Volatilität von Nahrungsmittelpreisen wieder als wichtiges Thema in der politischen Diskussion aufgetaucht. Nicht nur die Beobachtung eines steigenden Preisniveaus, sondern auch der scheinbare Anstieg der Volatilität auf Schlüsselmärkten (vor allem Getreide) hat viele Studien sowohl auf konzeptioneller als auch auf empirischer Ebene ausgelöst. Da Menschen, insbesondere in Entwicklungsländern, unter hohen und instabilen Preisen leiden, ist diese Entwicklung als globales Problem und ein Haupthindernis zur Bekämpfung von Hunger und Mangelernährung erkannt worden. Diese Doktorarbeit hat das Ziel, zu der Debatte beizutragen, wie am besten mit Preisvolatilität auf Agrarmärkten umzugehen ist. Um einen umfassenden Überblick über Agrarpreisvolatilität, ihre Ursachen und die Möglichkeiten, betroffenen Marktteilnehmern sinnvoll zu helfen, zu geben, konzentriert sich diese Arbeit auf drei bedeutende Aspekte, welche die drei Hauptkapitel dieser kumulativen Dissertation bilden: Kapitel 2 hat das Ziel, die Frage, wie sich Volatilität seit der Nahrungsmittelpreiskrise 2007/08 entwickelt hat, robust zu beantworten. Generelle Unterschiede im Volatilitätslevel, der Volatilität der Volatilität und der Persistenz der Volatilität werden für ein Set von realisierten, GARCH-Modell basierten und impliziten Volatilitäten auf drei Agrarmärkten – Weizen, Mais und Sojabohnen – betrachtet. Darüber hinaus werden verbreitete Aussagen bezüglich des Anstiegs der Volatilität seit der Nahrungsmittelpreiskrise 2007/08 und weitere relevante Aspekte wie die Veränderung der Persistenz der Volatilität und die Quantifizierung des Anstiegs hinsichtlich einer robusten Schlussfolgerung geprüft. Kapitel 3 identifiziert die Treiber von Volatilität für verschiedene Ölsaaten und pflanzliche Ölmärkte. Das Kapitel liefert eine Untersuchung der gemeinsamen Effekte von fundamentalen Volatilitätstreibern und der Übertragungseffekte zwischen verwandten Märkten. Kapitel 4 stellt ein Set von verwandten Risikomaßen vor, um die detaillierte Struktur der Volatilität in Agrarmärkten zu charakterisieren. Diese Maße erlauben die Zerlegung einer allgemeinen Preisbewegung in „große“ Veränderungen mit möglicherweise schwerwiegenden ökonomischen Konsequenzen und „normale“ Veränderungen. Es werden zukunftsgerichtete Schätzer der Risikomaße abgeleitet, die die Erwartungen des Marktes über zukünftige Bewegungen der Rohwarenpreise aus aktuellen Optionspreisen extrahieren. Eine empirische Studie für wichtige Getreidemärkte demonstriert die Vorhersagekraft der impliziten Schätzer. Insgesamt zeigt die Doktorarbeit, dass Risikomanagement und die Abmilderung der Effekte erhöhter Preisvolatilität nur dann wirkungsvoll ist, wenn man sich bewusst ist, welche Agrarmärkte betroffen sind, mit welcher genauen Art von Preisrisiko man konfrontiert ist und somit welche Gruppe von Marktteilnehmern Schutz benötigt und wenn das Risiko frühzeitig erkannt wird, um hilfreiche Maßnahmen zu unternehmen.

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.

Des travaux récents dans le domaine des mathématiques financières ont fait émerger l'importance de l'étude de la régularité et du comportement fin des queues de distribution pour certaines classes de diffusions à coefficients non globalement réguliers. Dans cette thèse, nous traitons des problèmes issus de ce contexte. Nous étudions d'abord l'existence, la régularité et l'asymptotique en espace de densités pour les solutions d'équations différentielles stochastiques en n'imposant que des conditions locales sur les coefficients de l'équation. Notre analyse se base sur les outils du calcul de Malliavin et sur des estimations pour les processus d'Ito confinés dans un tube autour d'une courbe déterministe. Nous obtenons des estimations significatives de la fonction de répartition et de la densité dans des classes de modèles comprenant des généralisations du CIR et du CEV et des modèles à volatilité locale-stochastique : dans ce deuxième cas, les estimations entraînent l'explosion des moments du sous-jacent et ont ainsi un impact sur le comportement asymptotique en strike de la volatilité implicite. La modélisation paramétrique de la surface de volatilité, à son tour, fait l'objet de la deuxième partie. Nous considérons le modèle SVI de J. Gatheral, en proposant une nouvelle stratégie de calibration quasi-explicite, dont nous illustrons les performances sur des données de marché. Ensuite, nous analysons la capacité du SVI à générer des approximations pour les smiles symétriques, en le généralisant à un modèle dépendant du temps. Nous en testons l'application à un modèle de Heston (sans et avec déplacement), en générant des approximations semi-fermées pour le smile de volatilité / Some recent works in the field of mathematical finance have brought new light on the importance of studying the regularity and the tail asymptotics of distributions for certain classes of diffusions with non-globally smooth coefficients. In this Ph.D. dissertation we deal with some issues in this framework. In a first part, we study the existence, smoothness and space asymptotics of densities for the solutions of stochastic differential equations assuming only local conditions on the coefficients of the equation. Our analysis is based on Malliavin calculus tools and on « tube estimates » for Ito processes, namely estimates for the probability that the trajectory of an Ito process remains close to a deterministic curve. We obtain significant estimates of densities and distribution functions in general classes of option pricing models, including generalisations of CIR and CEV processes and Local-Stochastic Volatility models. In the latter case, the estimates we derive have an impact on the moment explosion of the underlying price and, consequently, on the large-strike behaviour of the implied volatility. Parametric implied volatility modeling, in its turn, makes the object of the second part. In particular, we focus on J. Gatheral's SVI model, first proposing an effective quasi-explicit calibration procedure and displaying its performances on market data. Then, we analyse the capability of SVI to generate efficient approximations of symmetric smiles, building an explicit time-dependent parameterization. We provide and test the numerical application to the Heston model (without and with displacement), for which we generate semi-closed expressions of the smile

This thesis challenges some of the current limits to the grounds for judicial review of legislation accepted by most Canadian jurists. More specifically, it makes a common law-based argument in favour of the priority over legislation of principles which are implied from the Imperial Constitution Acts 1867-1982 and which originally derive from the English constitution – namely implied constitutional principles. The argument faces two main interrelated legal objections: Parliamentary sovereignty and the Framers’ intentions. The first objection is rebutted by arguing that Parliamentary sovereignty possesses an ability to change in a way that can incorporate substantive legal limitations. The most prevalent common law-based theories of change to Parliamentary sovereignty suggest that the courts can authoritatively determine if implied constitutional principles can check legislation. The second objection is rebutted by reference to the notion of progressive interpretation as conceived under Hartian and Dworkinian theories of law and adjudication. Under these theories, progressive interpretation is an aspect of the courts’ best overall interpretation of the constitution, which includes implied constitutional principles. Such progressive interpretation can result in these principles constraining legislative authority. Justification of the progressive interpretation of implied constitutional principles can be based on the rule of law from which derive a number of these principles. One plausible conception of the Canadian rule of law is that it rejects the view that implied constitutional principles can prevail when in conflict with legislation. However, the better conception is that, as an attempt to adapt implied constitutional principles to relevant changes in society and to protect their underlying values, the judiciary should interpret these principles as capable of checking legislation to the extent that they form part of the core content of the rule of law. Such a conception and an operation of implied constitutional principles can properly be explained by Hartian or Dworkinian common law-based progressive interpretation of these principles and by their relationship with legislative authority.

The diploma thesis introduces critically selected theoretical concepts that try to describe characteristics of children's and youth literature (further: LPDM). It focuses on approx. last thirty years of foreign research in LPDM. Firstly, the attention is paid to theories analyzing LPDM for specific qualities of appropriate texts. Then, the thesis presents theories which primarily describe LPDM on the base of specific context: the context in which the works emerged and are (expertly and non-expertly) received. Finally, the diploma thesis concerns with the potential benefit of presented theories but also with their problematic parts. By that it tries to offer new tools of productive analysis and interpretation of LPDM to Czech discourse of literary science.