Cette thèse traite de la modélisation des dérivés de crédit et se compose de deux parties: La première partie concerne le modèle à densité, récemment proposé par El Karoui et al. où on fait l'hypothèse que la loi conditionnelle de temps de défaut sachant la filtration référence est équivalente à sa loi (non-conditionnelle). Sous cette hypothèse, nous donnons des démonstrations différentes (et plus simples) aux résultats déjà existant dans la théorie du grossissement initial et progressif des filtrations. En outre, nous présentons de nouveaux résultats comme par exemple le théorème de représentation prévisible pour la filtration progressivement grossie dans le cas multidimensionnel. Nous proposons ensuite plusieurs méthodes pour construire des modèles à densité, dans les cas unidimensionnel et multidimensionnel. Enfin, nous montrons que le modèle à densité est une approche efficace pour la couverture dynamique de produits dérivés de crédit multi-name. Dans la deuxième partie, afin d'étudier le risque de contrepartie dans un contrat de CDS, nous avons proposé un modèle markovien dans lequel des défauts simultanés sont possibles. Le wrong-way risk est donc représenté par le fait que, à moment de la défaillance de la contrepartie, il y a une probabilité strictement positive pour que l'entité de référence fasse défaut aussi. Nous commençons par considérer une chaîne de Markov à quatre états correspondant à deux noms; Dans ce cas simple, nous obtenons des formules semi-explicites pour la plupart des quantités importantes, comme le prix, la CVA, l’EPE ou les ratios de couverture. Nous généralisons ensuite ce cadre pour tenir compte du risque de spread en introduisant des facteurs stochastiques; nous traitons un modèle copule Markovien avec des intensités stochastiques. Nous abordons également la question de la couverture dynamique du CVA avec un CDS écrit sur la contrepartie. Pour l'implémentation du modèle, nous spécifions les intensités par des processus affines, ce qui compte tenu de la propriété copule dynamique du modèle, rend la calibration de ce modèle efficace. Les résultats numériques sont présentés pour montrer la pertinence du comportement de la CVA dans le modèle avec les faits stylisés du marché. / This thesis deals with credit derivatives modeling and consists of two parts: The first part concerns the density model, recently proposed by El Karoui et al., where the standing assumption is that the conditional law of default time given the reference filtration is equivalent to its (non-conditional) law. Under this assumption, we provide alternative (and simpler) proofs for some existing results in the theory of initial and progressive enlargement of filtrations. Also, we present some new results such as the predictable representation theorem for progressively enlarged filtration in the multidimensional case. We then propose several methods to construct density models, in both one-dimensional and multidimensional cases. Finally, we show that the density model is an efficient approach for dynamic hedging of multi-name credit derivatives. In the second part, a Markov model is constructed for studying the counterparty risk in a CDS contract. The wrong-way risk in this model is accounted for by the possibility of the simultaneous default of the reference name and of the counterparty. We start by considering a Markov chain model of two reference credits, the firm underlying the CDS and the protection seller in the CDS. In this set-up, we have semi-explicit formulae for most quantities of interest with regard to CDS counterparty risk like price, CVA, EPE or hedging strategies. We then generalize this framework to account for the spread risk by introducing stochastic factors, so that, we deal with a Markov copula model with stochastic intensities. We also address the issue of dynamically hedging the CVA with a CDS written on the counterparty. For model implementation, we consider three different affine specification of the intensities, which in view of the dynamic copula property of the model, make calibration very efficient. Numerical results are presented to show the adequacy of the behavior of CVA in the model with stylized features.

Submitted by Rodrigo Trintino Ibelli (rtrintino@gmail.com) on 2015-09-03T14:07:52Z No. of bitstreams: 1 Rodrigo Ibelli - Dissertação MPFE 2015.pdf: 3255284 bytes, checksum: 0de3609857bb415d5d0cbb497ca4bcc9 (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Rodrigo, boa tarde Seu trabalho foi rejeitado por não estar de acordo com as normas da ABNT. Estaremos encaminhando por e-mail o que deverá ser alterado. Att on 2015-09-03T17:24:46Z (GMT) / Submitted by Rodrigo Trintino Ibelli (rtrintino@gmail.com) on 2015-09-04T12:56:55Z No. of bitstreams: 1 Dissertaçao Rodrigo Trintino - MPFE 2015.pdf: 3252833 bytes, checksum: f36bd64ae587c8593a352f10e413b4b9 (MD5) / Rejected by Renata de Souza Nascimento (renata.souza@fgv.br), reason: Encaminhado por e-mail. on 2015-09-04T13:40:06Z (GMT) / Submitted by Rodrigo Trintino Ibelli (rtrintino@gmail.com) on 2015-09-04T15:35:27Z No. of bitstreams: 1 Rodrigo Ibelli - Dissertaçao MPFE 2015.pdf: 3252967 bytes, checksum: 704103711c8bcb1cb74c851713c144b3 (MD5) / Approved for entry into archive by Renata de Souza Nascimento (renata.souza@fgv.br) on 2015-09-04T15:36:29Z (GMT) No. of bitstreams: 1 Rodrigo Ibelli - Dissertaçao MPFE 2015.pdf: 3252967 bytes, checksum: 704103711c8bcb1cb74c851713c144b3 (MD5) / Made available in DSpace on 2015-09-04T21:12:42Z (GMT). No. of bitstreams: 1 Rodrigo Ibelli - Dissertaçao MPFE 2015.pdf: 3252967 bytes, checksum: 704103711c8bcb1cb74c851713c144b3 (MD5) Previous issue date: 2015-08-12 / A stock swap transaction is an alternative way for a company who want to enter into a long position on its own stocks or who intend to set up a repurchase program without having to dispose of cash or contract a loan, or even hedging against increases on its stock prices. In this swap transaction the company receives the return on its own stock, whilst paying a fixed or floating interest rate. However, this kind of swap presents wrong-way risk, that is, a positive dependence between the underlying asset and the counterparty’s default probability, which must be considered by dealers when pricing this kind of swap contracts. In this work we propose a model for incorporating dependence between default probabilities and the counterparty’s exposure in the calculation of the CVA for these kind of swaps. We use a Cox process to model default times, given that the stochastic default intensity follows a CIR model, and assuming that the factor driving the underlying stock price and the factor driving the default intensity are jointly given by a bivariate standard Gaussian distribution. We analyze the impact on CVA of incorporating wrong-way risk in this kind of swap transaction with different counterparties, and for different maturities and dependence levels. / Uma forma interessante para uma companhia que pretende assumir uma posição comprada em suas próprias ações ou lançar futuramente um programa de recompra de ações, mas sem precisar dispor de caixa ou ter que contratar um empréstimo, ou então se protegendo de uma eventual alta no preço das ações, é através da contratação de um swap de ações. Neste swap, a companhia fica ativa na variação de sua própria ação enquanto paga uma taxa de juros pré ou pós-fixada. Contudo, este tipo de swap apresenta risco wrong-way, ou seja, existe uma dependência positiva entre a ação subjacente do swap e a probabilidade de default da companhia, o que precisa ser considerado por um banco ao precificar este tipo de swap. Neste trabalho propomos um modelo para incorporar a dependência entre probabilidades de default e a exposição à contraparte no cálculo do CVA para este tipo de swap. Utilizamos um processo de Cox para modelar o instante de ocorrência de default, dado que a intensidade estocástica de default segue um modelo do tipo CIR, e assumindo que o fator aleatório presente na ação subjacente e que o fator aleatório presente na intensidade de default são dados conjuntamente por uma distribuição normal padrão bivariada. Analisamos o impacto no CVA da incorporação do riscowrong-way para este tipo de swap com diferentes contrapartes, e para diferentes prazos de vencimento e níveis de correlação.

過去實證研究發現，資產的動態過程存在不連續的跳躍與大波動伴隨大波動的波動度叢聚現象而造成資產報酬分配呈現出厚尾與高狹峰的情況，然而，此現象並不能完全被傳統所使用幾何布朗運動模型與跳躍擴散模型給解釋。因此，本文設定資產模型服從Lévy 過程中Generalized Hyperbolic (GH)的normal inverse Gaussian(NIG) 和 variance gamma (VG)兩個模型，然而，Lévy 過程是一個跳躍過程，是屬於一個不完備的市場，這將使得平賭測度並非唯一，因此，本文將採用Gerber 和 Shiu (1994)所提的Esscher 轉換來求得平賭測度。關於美式選擇權將採用LongStaff and Schwartz (2001)所提的最小平方蒙地卡羅模擬法來評價美式選擇權。實證結果發現VG有較好的評價績效，此外，進一步探討流動性與價內外的情況對於評價誤差的影響，亦發現部分流動性高的樣本就較小的評價誤差；此外，價外的選擇權其評價誤差最大。另一方面從交易的觀點來看，次貸風暴後交易對手信用風險愈來愈受到重視，此外，近年來由於巨災事件的頻傳，使得傳統保險公司風險移轉的方式，漸漸透過資本市場發行衍生性商品來進行籌資，以彌補其在巨災發生時所承擔的損失。因此，透過發行衍生性商品來進行籌資，必須考量交易對手的信用風險，否則交易對手違約，就無法獲得額外的資金挹注，因此，本文評價巨災權益賣權，並考量交易對手信用風險對於其價格的影響。 / In the traditional models such as geometric Brownian motion model or the Merton jump diffusion model can’t fully depict the distributions of return for financial securities and the those return always have heavy tail and leptokurtic phenomena due to the price jump or volatilities of return changing over time. Hence, the first article uses two time-changed Lévy models: (1) normal inverse Gaussian model and (2) variance gamma model to capture the dynamics of asset for pricing American option. In order to deal with the early-exercised problem of the American option, we use the LSM to determine the optimal striking point until maturity. In the empirical analyses, we can find the VG model have better performance than the other three models in some cases. In addition, with the comparison the pricing performance under different liquidity and moneyness conditions, we also find in some samples increasing the liquidity really can reduce the pricing errors, at the same time, the maximum pricing errors appears in the OTM samples in all cases. The global subprime crisis during 2008 and 2009 arouses much more attention of the counterparty risk and the number of default varies with economic condition. Hence, we investigate the counterparty risk impact on the price of the catastrophe equity put with a Markov-modulated default intensity model in the second study. At the same time, we also extend the stochastic interest rate setting in Jaimungal and Wang (2006) and relax some restrictive assumption of Black-Scholes model by taking the regime-switching effects of the economic status, then use the Markov-modulated processes to model the dynamics of the underlying asset and interest rate. In the numerical analyses, we illustrate the impact of the recovery rate, time to maturity, jump intensity of the equity and default intensity of counterparty on the CatEPut price.

Au lendemain de la crise financière de 2008, les autorités se sont emparées de la question du risque de contrepartie associé aux produits dérivés de gré à gré. Les dix années qui se sont écoulées depuis permettent de dresser le bilan de l’efficacité du cadre règlementaire alors mis en place. Cette étude s’attache à cartographier les différents éléments qui composent ou alimentent le risque de contrepartie en matière de dérivés de gré à gré et analyse l’efficacité des diverses techniques déployées pour le gérer. Les outils de gestion utilisés en matière de dérivés de gré à gré afin d’atténuer le risque de contrepartie reposent sur une pluralité de mécanismes juridiques (légaux ou contractuels). Si certains sont à la libre disposition des parties, d’autres leur sont imposés par la règlementation. Tous ces instruments participent – seuls ou conjointement – à atténuer réellement le risque de contrepartie. Mais chacun d’eux ne traite néanmoins qu’un aspect particulier de ce risque et aucun ne permet de l’annihiler totalement. Certaines situations viennent même parfois perturber l’efficacité des outils de gestion du risque de contrepartie et anéantissent leurs effets bénéfiques. On comprend in fine que la gestion efficace du risque de contrepartie suppose le respect de trois étapes : l’identification des risques attachés à chaque opération en présence doit précéder l’élaboration des outils de gestion en vue de leur atténuation, laquelle suppose enfin la prévention du risque d’inefficacité des outils utilisés. Dans tous les cas, la gestion du risque de contrepartie en matière de dérivés de gré à gré s’avère non seulement imparfaite mais aussi éminemment fragile. / Ln the aftermath of the 2008 financial crisis, the authorities tackled the issue of counterparty risk associated with OTC derivatives. The ten years that have passed since then allow us an opportunity to take stock of the effectiveness of the regulatory framework then put in place. This study aims to map the different elements that make up or feed the counterparty risk in OTC derivatives and analyzes the effectiveness of the various techniques deployed to manage it. The management tools used in OTC derivatives to mitigate counterparty risk rely on a variety of legal mechanisms. If some are at the free disposal of the parties, others are imposed by the regulations. All these instruments participate -alone or jointly-in actually mitigating the counterparty risk. But each of them only deals with a particular aspect of this risk and none of them can completely neutralise it. Some situations even sometimes disrupt the effectiveness of counterparty risk management tools and negate their beneficial effects. Ultimately, it is understood that the effective management of counterparty risk requires three stages: the identification of the risks attached to each operation, followed by the development of relevant management tools with a view to the mitigation of such risks, and finally steps to avoid the risk of inefficiency of the tools used. ln any case, counterparty risk management in OTC derivatives is not only imperfect but also eminently fragile.

Project finance has become a vital financing vehicle for undertaking capital-intensive and infrastructure investments. In 2017 alone, the value of deals signed using project finance was estimated at approximately $229 billion. Despite its increasing importance, little is known regarding the impact of project-level, and country characteristics on the loan terms. This thesis proceeds in examining these determinants along three empirical essays. The first essay (Chapter 3) focuses on how domestic lead arrangers certification (in emerging markets) impact the pricing of project finance loans. Using a sample 1270 project finance loan tranches signed between 1998 and 2011, and worth over $300 billion, the chapter posits that domestic lead arrangers certification reduce search and information cost, which in turn, reduces the financing cost. The results, after controlling for endogeneity of certification decision, indicate a reduction of 47 basis points in the spread offered on PF loans. The magnitude of this reduction differs across industries, geographic region, and income classification of the project countries. The second essay (Chapter 4) examines the relationship between PF contractual structures and loan outcomes, using a sample of 5872 project finance loan tranches signed between 1998 and 2013, and worth approximately $1.2 trillion. The chapter hypothesises that (i) non financial contracts (NFCs) (that is, contracts used to manage the various project functions), reduces overall project risk, (ii) the involvement of project sponsors as key counterparties to the non-financial contracts is an additional signal of project s potential worth, and (iii) the effects observed in (i and ii) are stronger, if sponsor counterparties have verifiable credit ratings. After matching loan tranches with NFCs to those without, the results indicate that the use of NFCs reduce both the loan spreads and leverage ratios. This impact is higher if the sponsor counterparties are credit-rated. The results are also stronger for developing countries. The third essay examines the impact of country-level institutions on project finance loan spread and leverage ratio, using a sample of 3,362 loan tranches signed between the year 1998 - 2012. The chapter investigates whether political and legal institutions are substitutes (or complements), that is, if improvement in one absorbs the weakness of the other, and vice versa. Further, the essay examines if project finance network of contracts substitutes for these institutions. The results indicate that political and legal institutions are substitutes. Specifically, improvements in political institutions lead to a reduction in both the loan spread and leverage ratio for countries with weak legal and governance institutions. The chapter also finds that where NFCs are included in PF, the impact of political institutions on loan spread reduces. On the other hand, the impact of political institutions on leverage ratio is higher when NFCs are used. The findings from the three research chapters provide interesting insights on how lenders and sponsors create value through contract design.

Diss. Stockholm : Handelshögskolan, 2009

A mixed integer linear programming formulation is used to solve the problem of allocating assets from a bank to its counterparties as collateral within securities lending. The aim of the optimisation is to reduce the cost of allocated collateral, which is broken down into the components opportunity cost, counterparty risk cost and triparty cost. A solution consists of transactions to carry out to improve the allocation cost, each transaction consisting of sending a quantity of some asset from a portfolio to the bank or from the bank to some portfolio. The optimisation process is split into subproblems to separate obvious transactions from more complex optimisations. The reduction of each cost component is examined for all the subproblems. Two subproblems transform an initial collateral allocation into a feasible one which is then improved by the optimisation. Decreasing opportunity cost is shown to be an easier task than decreasing counterparty risk and triparty costs since the latter costs require a comparatively large number of transactions. The optimisation is run several times in a row, performing the suggested transactions after each solved iteration. The cost reduction of k optimisation iterations with 10 transactions per iteration is shown to be similar to the cost reduction of 1 optimisation iteration with 10k transactions. The solution time increases heavily with the number of iterations. The suggested transactions may need to be performed in a certain order. A precedence constrained problem takes this into account. The problem is large and the execution time is slow if a limit is imposed on the number of allowed transactions. A strategic selection of portfolios can limit the number of suggested transactions and still reach a solution which comes close to the optimal one. This can also be done by requiring that all suggested transactions must reduce the cost by a minimum amount. The final model is ready to be used in a semi-automatic fashion, where transactions are verified by a human who checks if they are sound. A fully automated process requires further testing on historical and recent data. / Ett blandat-heltal linjärt optimeringsproblem används för att lösa uppgiften att tilldela värdepapper från en bank till dess kunder som pant för värdepapperslån. Målet med optimeringen är att minska kostnaden av den tilldelade panten. Kostnaden bryts ned i komponenterna alternativkostnad, motpartsrisk och tripartykostnad. En lösning består av föreslagna transaktioner som ska genomföras för att förbättra den nuvarande säkerhetstilldelningens kostnad. En transaktion består av att ta hem eller skicka ut en kvantitet av ett visst värdepapper från eller till en av bankens kunders portföljer. Optimeringsproblemet bryts ned i flera delproblem med syfte att särskilja uppenbara föreslagna säkerheter till en godkänd tildelning som sedan blir en startpunkt för optimeringen. Att minska alternativkostnad visar sig vara enklare än att minska motpartsrisk och tripartykostnader på så sätt att de sistnämnda kostnaderna kräver fler transaktioner för att minskas. Optimeringen körs flera gånger i rad, där alla föreslagna transaktioner från en iteration genomförs innan nästa iteration körs. Kostnadsminskningen av k körningar med 10 transaktioner visar sig vara väldigt nära, om än något mindre, än en körning med 10k transaktioner. Exekveringstiden ökar drastiskt med antalet iterationer. De föreslagna transaktionerna kan behöva genomföras i en viss ordning. En problemformulering konstrueras som tar höjd för detta, men exekveringstiden är extremt lång när antalet transaktioner begränsas. Ett strategiskt urval av portföljer kan begränsa antalet föreslagna transaktioner utan att försämra lösningen särskilt mycket. På ett liknande sätt kan antalet föreslagna transaktioner minskas genom att lägga till ett villkor som säger att lönsamheten av en transaktion måste överskrida en given minsta tröskel. Den slutgiltiga modellen är redo att användas om de föreslagna transaktionerna granskas manuellt innan de genomförs. En helt automatisk process ligger längre fram i tiden efter ytterligare tester på historisk och nuvarande data.

Subprime residential mortgage loan securitization and its associated risks have been a major topic of discussion since the onset of the subprime mortgage crisis (SMC) in 2007. In this regard, the thesis addresses the issues of subprime residential mortgage loan (RML) securitization in discrete-, continuous-and discontinuous-time and their connections with the SMC. In this regard, the main issues to be addressed are discussed in Chapters 2, 3 and 4. In Chapter 2, we investigate the risk allocation choices of an investing bank (IB) that has to decide between risky securitized subprime RMLs and riskless Treasuries. This issue is discussed in a discrete-time framework with IB being considered to be regret- and risk-averse before and during the SMC, respectively. We conclude that if IB takes regret into account it will be exposed to higher risk when the difference between the expected returns on securitized subprime RMLs and Treasuries is small. However, there is low risk exposure when this difference is high. Furthermore, we assess how regret can influence IB's view - as a swap protection buyer - of the rate of return on credit default swaps (CDSs), as measured by the premium based on default swap spreads. We find that before the SMC, regret increases IB's willingness to pay lower premiums for CDSs when its securitized RML portfolio is considered to be safe. On the other hand, both risk- and regret-averse IBs pay the same CDS premium when their securitized RML portfolio is considered to be risky. Chapter 3 solves a stochastic optimal credit default insurance problem in continuous-time that has the cash outflow rate for satisfying depositor obligations, the investment in securitized loans and credit default insurance as controls. As far as the latter is concerned, we compute the credit default swap premium and accrued premium by considering the credit rating of the securitized mortgage loans. In Chapter 4, we consider a problem of IB investment in subprime residential mortgage-backed securities (RMBSs) and Treasuries in discontinuous-time. In order to accomplish this, we develop a Levy process-based model of jump diffusion-type for IB's investment in subprime RMBSs and Treasuries. This model incorporates subprime RMBS losses which can be associated with credit risk. Furthermore, we use variance to measure such risk, and assume that the risk is bounded by a certain constraint. We are now able to set-up a mean-variance optimization problem for IB's investment which determines the optimal proportion of funds that needs to be invested in subprime RMBSs and Treasuries subject to credit risk measured by the variance of IE's investment. In the sequel, we also consider a mean swaps-at-risk (SaR) optimization problem for IB's investment which determines the optimal portfolio which consists of subprime RMBSs and Treasuries subject to the protection by CDSs required against the possible losses. In this regard, we define SaR as indicative to IB on how much protection from swap protection seller it must have in order to cover the losses that might occur from credit events. Moreover, SaR is expressed in terms of Value-at-Risk (VaR). Finally, Chapter 5 provides an analysis of discrete-, continuous- and discontinuous-time models for subprime RML securitization discussed in the aforementioned chapters and their connections with the SMC. The work presented in this thesis is based on 7 peer-reviewed international journal articles (see [25], [44], [45], [46], [47], [48] and [55]), 4 peer-reviewed chapters in books (see [42], [50j, [51J and [52]) and 2 peer-reviewed conference proceedings papers (see [11] and [12]). Moreover, the article [49] is currently being prepared for submission to an lSI accredited journal. / Thesis (Ph.D. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2010.

Subprime residential mortgage loan securitization and its associated risks have been a major topic of discussion since the onset of the subprime mortgage crisis (SMC) in 2007. In this regard, the thesis addresses the issues of subprime residential mortgage loan (RML) securitization in discrete-, continuous-and discontinuous-time and their connections with the SMC. In this regard, the main issues to be addressed are discussed in Chapters 2, 3 and 4. In Chapter 2, we investigate the risk allocation choices of an investing bank (IB) that has to decide between risky securitized subprime RMLs and riskless Treasuries. This issue is discussed in a discrete-time framework with IB being considered to be regret- and risk-averse before and during the SMC, respectively. We conclude that if IB takes regret into account it will be exposed to higher risk when the difference between the expected returns on securitized subprime RMLs and Treasuries is small. However, there is low risk exposure when this difference is high. Furthermore, we assess how regret can influence IB's view - as a swap protection buyer - of the rate of return on credit default swaps (CDSs), as measured by the premium based on default swap spreads. We find that before the SMC, regret increases IB's willingness to pay lower premiums for CDSs when its securitized RML portfolio is considered to be safe. On the other hand, both risk- and regret-averse IBs pay the same CDS premium when their securitized RML portfolio is considered to be risky. Chapter 3 solves a stochastic optimal credit default insurance problem in continuous-time that has the cash outflow rate for satisfying depositor obligations, the investment in securitized loans and credit default insurance as controls. As far as the latter is concerned, we compute the credit default swap premium and accrued premium by considering the credit rating of the securitized mortgage loans. In Chapter 4, we consider a problem of IB investment in subprime residential mortgage-backed securities (RMBSs) and Treasuries in discontinuous-time. In order to accomplish this, we develop a Levy process-based model of jump diffusion-type for IB's investment in subprime RMBSs and Treasuries. This model incorporates subprime RMBS losses which can be associated with credit risk. Furthermore, we use variance to measure such risk, and assume that the risk is bounded by a certain constraint. We are now able to set-up a mean-variance optimization problem for IB's investment which determines the optimal proportion of funds that needs to be invested in subprime RMBSs and Treasuries subject to credit risk measured by the variance of IE's investment. In the sequel, we also consider a mean swaps-at-risk (SaR) optimization problem for IB's investment which determines the optimal portfolio which consists of subprime RMBSs and Treasuries subject to the protection by CDSs required against the possible losses. In this regard, we define SaR as indicative to IB on how much protection from swap protection seller it must have in order to cover the losses that might occur from credit events. Moreover, SaR is expressed in terms of Value-at-Risk (VaR). Finally, Chapter 5 provides an analysis of discrete-, continuous- and discontinuous-time models for subprime RML securitization discussed in the aforementioned chapters and their connections with the SMC. The work presented in this thesis is based on 7 peer-reviewed international journal articles (see [25], [44], [45], [46], [47], [48] and [55]), 4 peer-reviewed chapters in books (see [42], [50j, [51J and [52]) and 2 peer-reviewed conference proceedings papers (see [11] and [12]). Moreover, the article [49] is currently being prepared for submission to an lSI accredited journal. / Thesis (Ph.D. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2010.

Cette thèse se propose d’analyser la structure et la dynamique de dépendance de crédit des institutions financières aux Etats-Unis et en Europe durant la crise financière de 2008. Un premier chapitre présente une revue de la littérature des modèles multi-dimensionnels de crédit et des modèles économétriques de contagion financière. Ce chapitre a pour vocation de guider notre réflexion à la fois conceptuelle et méthodologique sur les hypothèses analytiques de la contagion ainsi que ses méthodes de mesure. Nous montrons que si la contagion est devenue une hypothèse centrale des modèles multivariés de risque de crédit, il n’en reste néanmoins que sa définition et sa quantification ne font pas l’objet de consensus dans la littérature. Un deuxième chapitre propose une analyse empirique des co-movements des rendements de CDS de banques et sociétés d’assurance américaines et européennes. La dissociation de leur structure de dépendance entre association linéaire et dépendances extrêmes nous permet de mettre en évidence des phénomènes d'interconnexions entre institutions financières apparues au courant de la crise et véhiculant ainsi sous l'effet de la contagion, un risque systémique croissant. Un dernier chapitre présente une interprétation économique des résultats obtenus dans notre deuxième chapitre. En particulier, nous cherchons à quantifier l'influence jouée par la contagion et les facteurs de risques communs sur la dynamique de dépendance extrême des institutions financières. Nous démontrons ainsi le rôle du risque de contrepartie, du risque de liquidité et du risque de défaut des institutions financières dans la transmission de la contagion sur le marché de CDS. / This thesis examines the credit dependence structure and dynamics of financial institutions in the U.S. and Europe amid the recent financial crisis. A first chapter presents a survey of multi-name models of credit risk and econometric models of financial contagion with the purpose of guiding both the analytical and conceptual assumptions and econometric modelling techniques we use in the subsequent chapters. We show that if contagion has become a central cornerstone of multi-name models of credit risk, there is nonetheless a lack of consensus on the way to both define and measure it. A second chapter presents the results of an empirical analysis of U.S. and European banks and insurance companies’ CDS return extreme co-movements. By uncovering financial institutions' linear as well as extremal dependence structures, we provide evidence that their credit dependence has strengthened during the crisis, thereby effectively conveying, in the face of extreme tail events, potential systemic risks. A third and last chapter provides an economic rationale of the results presented in our second chapter. In particular, we examine the impact of common risk factors and contagion on the dynamics of financial institutions' extremal credit dependence. We demonstrate the role of counterparty risk and liquidity risk, as well the repricing by market participants since July 2007 of their jump-to-default premia as additional channels driving financial institutions' increased dependence and amplifying contagion on the CDS market.