Cette thèse est constituée de trois essais sur les activités de fusions-acquisitions (F&A) des banques et leurs effets sur la stabilité du secteur bancaire. Le premier essai analyse l’intensité de l’activité F&A des grandes banques Européennes au cours d'une période vaste de 1990-2006 et les liens avec les mesures de sauvetages et les notations de crédit pendant la crise financière de 2007-2009. Trois résultats importants sont mis en évidence à partir de notre étude. En premier lieu, l'intensité de l'activité F&A est liée positivement à la probabilité de sauvetage pendant la crise financière. En second lieu, cette intensité des activités de F&A est liée à la détérioration des notations des émetteurs, suggérant ainsi un risque de défaut plus élevé des banques acquéreuses pendant la période de crise. Enfin, on constate un lien positif entre les mesures de protection gouvernementales et l'effet combiné des activités de F&A et du facteur « too big to fail ». Ceci laisse penser que les banques peuvent poursuive leurs activités de F&A pour exploiter des avantages de protection liés à leur statut de « too big to fail ». Le second essai analyse la relation entre les activités de F&A de grandes banques Européennes et leur vulnérabilité à la crise financière en utilisant l’indicateur DD de Merton (1974) et le ratio de Z-score comme mesures de risque de faillite et de solvabilité. Les résultats mettent en évidence que les stratégies d’acquisition de banques d'investissements sur une période de 1990-2006 sont liées significativement à l'augmentation en leur risque de défaut (mesuré par DD) et l'insolvabilité (mesuré par le Z-score) pendant la crise financière récente. Le troisième et dernier essai s’intéresse aux relations entre les opérations de F&A et les évolutions de la déréglementation bancaire et des réformes de régulation bancaire mises en place aux Etats-Unis. Nous analysons principalement les effets de deux actes de déréglementation significatifs des années 1990 qui ont permis aux banques américaines de s’étendre à travers les états (acte de Riegle-Neal de 1994 et acte de Gramm-Leach-Bliley de 1999). Nous comparons les activités de F&A des banques américaines avec comme groupe de contrôle les banques européennes sur la période 1990-2009. Nous constatons un effet significativement positif de la déréglementation sur les activités de F&A dans le secteur bancaire américain. Cependant, on peut remarquer que les effets constatés ne sont pas forcément les effets souhaités ou visés par les deux actes de déréglementation. De plus, nous montrons que l'intensité des activités de F&A et la déréglementation provoquent conjointement un effet négatif sur la stabilité du secteur bancaire américain, justifiant ainsi le lien souvent établi entre la concentration du système bancaire et sa fragilité. / This dissertation consists of three essays on mergers and acquisitions (M&A) activity of banks and various dimensions of their stability. The first essay delves upon whether and how acquisitiveness of large European banks over an extensive period of 1990-2006 relate to their bailouts and credit ratings during the financial crisis of 2007-2009. Three important findings emerge from the performed analysis. First, the intensity of bank M&A activity positively relates to the likelihood and extent of their bailout support during the financial crisis. Second, the ex-ante acquisitiveness of banks relates in a significantly positive manner with the deterioration in bank issuer ratings – suggesting towards higher default risk of acquisitive banks during the crisis period. Third, a positive link between the external support and the joint effect of M&A activity and “too big to fail” factor substantiates that banks may pursue M&A activity to exploit safety net benefits associated with “too big to fail” status in the market. The second chapter analyzes the relation between M&A activity of large European banks and their vulnerability to the financial crisis using Merton (1974) based distance to default (DD) and the Z-score ratio as a measure of bankruptcy risk and solvency. The results suggest that a greater focus of samples banks towards acquiring investment banking operations over a time span of 1990-2006 significantly relates to the increase in their risk default (measured by DD) and insolvency (measured by Z-score) during the recent financial crisis. Moreover, relatively limited evidence indicates towards the positive stability effects of the acquisitions performed in the retail banking segment of industry by the sample banks. The third and final essay of this dissertation provides M&A centric evidence on bank deregulation, consolidation, and stability in the U.S. banking industry. We primarily analyze the effects of two significant deregulatory acts of the 1990s that permitted U.S. banks to expand across states (the Riegle-Neal act of 1994) and functions performed (the Gramm-Leach-Bliley act of 1999). We employ difference-in-difference approach over M&A activity of U.S. (treatment group) and European (control group) banks over a time span of 1990-2009 in an unbalanced panel setting. We find a significantly positive effect of deregulation in spurring M&A centric consolidation in the U.S. banking industry. However, such effects are not fully reflected in the types of diversification aimed at in the two deregulatory acts. Moreover, we also show that M&A intensity and deregulation jointly cast a negative effect on the stability of U.S. banking industry –thus substantiating “Concentration – Fragility” view over banking.

A partir d’une analyse du défaut des banques et de la régulation au travers des notations de crédits (et des agences de notation), des modèles portant sur les CDS, de Bâle III et du capital insurance, nous trouvons que les spécificités des CDS en font un bon candidat pour prévoir (et idéalement empêcher) les défauts potentiels des banques. En effet, grâce aux propriétés (financières et économiques) des CDS, ainsi qu’aux résultats d’études empiriques, nous montrons qu’ils reflètent correctement le comportement des risques des banques et qu’ils ont capté les changements informationnels plus rapidement que les notations de crédits qui sont restées relativement constantes durant 2007 et 2008.Ainsi, en utilisant un déclencheur ad hoc basé sur les CDS et l’action appropriée si le déclencheur venait à s’activer, nous pourrions empêcher le défaut d’une banque. Et la compréhension du mécanisme afférent au capital contingent est d’un grand intérêt pour atteindre cet objectif qui optimise le monitoring mis en oeuvre par les banques et les régulateurs. / Based on an analysis of the default of the banks and regulation through credit ratings (and rating agencies), CDS models, Basel III, bail-In and capital insurance, we find that the characteristics of CDS make them a good candidate to forecast (and ideally prevent) the potential defaults of the banks. Indeed, thanks to the economics of CDS and results of empirical studies, we show that they are a good proxy of bank risks and that they did capture information changes more quickly than the credit ratings which remained relatively constant during 2007 and 2008.So, using a specific trigger based on CDS and the appropriate action, should the trigger be activated, we could prevent the default of a bank. And the understanding of contingent capital mechanism is of great interest to reach this objective which optimizes the monitoring implemented by banks as well as regulators.

We examine the impact of Mergers & Acquisitions on credit- and investment risk using a sample of 402 acquisitions by 215 Swedish firms from 2000 to 2020. We find significant evidence that, on average, M&A increases the credit risk and inversely decreases the investment risk of the acquiring firm. Our results indicate that firm credit risk however is positively correlated with investment risk. After controlling for specific deal- and firm characteristics, our findings suggest that managerial hubris decreases the level of credit risk and increases the level of investment risk in acquiring firms. Our results are consistent with the asymmetric information hypothesis that managers may exploit the volatility of their stock price to hide risk-increasing activities. We also observe that acquirers with high pre-deal credit risk undertake acquisitions that decrease credit risk and increase investment risk. We find no significant impact from neither method of payment nor valuation errors.

An optimal dividend problem with investment opportunities, taking into consideration a source of strategic risk is being considered, as well as the effect of market frictions on the decision process of the financial entities. It concerns the problem of determining an optimal control of the dividend under debt constraints and investment opportunities in an economy with business cycles. It is assumed that the company is to be allowed to accept or reject investment opportunities arriving at random times with random sizes, by changing its outstanding indebtedness, which would impact its capital structure and risk profile. This work mainly focuses on the strategic risk faced by the companies; and, in particular, it focuses on the manager's problem of setting appropriate priorities to deploy the limited resources available. This component is taken into account by introducing frictions in the capital structure modification process. The problem is formulated as a bi-dimensional singular control problem under regime switching in presence of jumps. An explicit condition is obtained in order to ensure that the value function is finite. A viscosity solution approach is used to get qualitative descriptions of the solution. Moreover, a lending scheme for a system of interconnected banks with probabilistic constraints of failure is being considered. The problem arises from the fact that financial institutions cannot possibly carry enough capital to withstand counterparty failures or systemic risk. In such situations, the central bank or the government becomes effectively the risk manager of last resort or, in extreme cases, the lender of last resort. If, on the one hand, the health of the whole financial system depends on government intervention, on the other hand, guaranteeing a high probability of salvage may result in increasing the moral hazard of the banks in the financial network. A closed form solution for an optimal control problem related to interbank lending schemes has been derived, subject to terminal probability constraints on the failure of banks which are interconnected through a financial network. The derived solution applies to real bank networks by obtaining a general solution when the aforementioned probability constraints are assumed for all the banks. We also present a direct method to compute the systemic relevance parameter for each bank within the network. Finally, a possible computation technique for the Default Risk Charge under to regulatory risk measurement processes is being considered. We focus on the Default Risk Charge measure as an effective alternative to the Incremental Risk Charge one, proposing its implementation by a quasi exhaustive-heuristic algorithm to determine the minimum capital requested to a bank facing the market risk associated to portfolios based on assets emitted by several financial agents. While most of the banks use the Monte Carlo simulation approach and the empirical quantile to estimate this risk measure, we provide new computational approaches, exhaustive or heuristic, currently becoming feasible, because of both new regulation and the high speed - low cost technology available nowadays.

The financial stability of the insurers is important to fulfil its role as a risk transfer mechanism and to protect the purchasers of their products. The European Union is introducing the Solvency II to modernise the current Solvency I regime and to harmonise the different insurance legislation of the members of the European Union. Solvency II introduces an architecture consisting of three pillars, with Pillar I setting the solvency capital requirements, Pillar II the governance and risk management requirements and Pillar III the reporting requirements. The South African Regulator initiated Solvency Assessment and Management for implementation in 2016 to align the South African prudential regulatory framework to meet the Solvency II requirements for third country equivalence. The problem that this study addressed is the possible effect that the introduction of Solvency Assessment and Management may have on the sustainability of short-term insurers in South Africa. The results of a empirical component of the study indicated that small and medium short-term insurers may be negatively impacted due to the costs incurred to implement and comply with the requirements of the new regulatory framework. The effect on the South African short-term industry can be that cover is concentrated among a few large short-term insurers. / Business Management / M. Com. (Business Management)

本論文推導違約風險下四種新奇選擇權的評價模型及其避險比率，依序為數據選擇權、寬它選擇權、互換選擇權，極值選擇權。並比較無違約風險與違約風險下的評價模型之差異。假若違約風險不存在時，違約風險下各種類型選擇權的評價模型皆會縮減成為無違約風險下所對應的評價模型。避險比率亦為如此。數值範例則印證違約風險下選擇權的價值較無違約風險選擇權的價值低。本論文完成目前尚無任何學術研究於違約風險下四種新奇選擇權的評價模型及避險比率。這是一個重要貢獻。 關鍵詞：違約風險、新奇選擇權、數據選擇權、寬它選擇權、互換選擇權、極值選擇權。 / This paper presents the analytic pricing formula and the hedging ratio of four kinds of exotic options with correlated credit risk. They are Digital options, Quanto Options, Exchange Options and Extreme-value Options, respectively. Furthermore, compare the discrepancy of the models under the condition whether the default risk exists. Finding that if there is no default risk, all models that we derive will reduce to the corresponding models with no default risks, and so do the hedging ratio. Numerical examples certify that the value of the vulnerable options will be lower than that of the ordinary options. All above that finished has not been done by existing researches and it is a chief contribution in this paper. Keywords: Exotic Options, Credit Risk, Digital Options, Quanto Options, Exchange Options, Extreme-value Options, Default Risk.

Il y a quatre chapitres dans cette thèse.Dans le premier chapitre, nous analysons les intéractions entre le marché interbancaire et le risque de défaut souverain dans un modèle d’équilibre général à deux pays, en focalisant sur la transmission de la crise financière récente et la politique monétaire non conventionnelle.Dans le deuxième chapitre, les effets de la dévaluation fiscale sur les indicateurs macroéconomiques et le bien être sont analysés en utilisant un modèle à deux pays en union monétaire o`u les variétés de biens et le commerce sont endogènes.Dans le troisième chapitre, l’impact du facteur démographique sur la croissance du secteur des services à long terme est mis en exergue.Dans le quatrième chapitre, on étudie les effets de la mobilité des travailleurs et de la mobilité du capital dans une union monétaire. / This thesis studies challenges for modern developped economies, including the structural change toward services, population ageing, weak labor mobility in the EMU and unconventional monetary policies after the 2008 financial crisis. The manuscript is divided into four chapters.In the first chapter, we analyze the interaction between interbank markets and default risk using a two-country dynamic general equilibrium model, with a focus on the transmission of the recent financial crisis and unconventional monetary policies.In the second chapter, we investigate the effects of fiscal devaluations on key macroeconomic aggregates and welfare using a two-country monetary-union model with endogenous varieties and endogenous tradability.In the third chapter, we study the impact of demographic factor and the growth of service sector by using a multi-sectoral OLG model, and effectuate counterfactual experiments in which the annual growth rate of young generation is ±1pp than the actual growth rate.In the fourth chapter, we study the potential interactions between financial integration and labor mobility in a currency union facing asymmetric shocks, and simulate the impacts of 2008 financial crisis under different mobility costs.

The financial stability of the insurers is important to fulfil its role as a risk transfer mechanism and to protect the purchasers of their products. The European Union is introducing the Solvency II to modernise the current Solvency I regime and to harmonise the different insurance legislation of the members of the European Union. Solvency II introduces an architecture consisting of three pillars, with Pillar I setting the solvency capital requirements, Pillar II the governance and risk management requirements and Pillar III the reporting requirements. The South African Regulator initiated Solvency Assessment and Management for implementation in 2016 to align the South African prudential regulatory framework to meet the Solvency II requirements for third country equivalence. The problem that this study addressed is the possible effect that the introduction of Solvency Assessment and Management may have on the sustainability of short-term insurers in South Africa. The results of a empirical component of the study indicated that small and medium short-term insurers may be negatively impacted due to the costs incurred to implement and comply with the requirements of the new regulatory framework. The effect on the South African short-term industry can be that cover is concentrated among a few large short-term insurers. / Business Management / M. Com. (Business Management)

房屋貸款保證保險制度可移轉部分違約風險予保險公司。然而，保險公司與金融機構在共同承擔風險之際，因房貸保證保險制度之施行，於提高貸款成數後，產生違約風險提高之矛盾現象；而估計保險之預期損失時，以目前尚無此制度下之違約數據估計損失額，將有錯估之可能。 本研究以二元邏吉斯特迴歸模型(Binary Logistic Regression Model)與存活分析(Survival Analysis)估計違約行為，並比較各模型間資料適合度及預測能力，進而單獨分析變數-貸款成數對違約率之邊際機率影響。以探討房貸保證保險施行後，因其對借款者信用增強而提高之貸款成數，所增加之違約風險。並評估金融機構因提高貸款成數後可能之違約風險變動，據以推估違約率數據，並根據房貸保證保險費率結構模型，計算可能之預期損失額，估算變動的保險費率。 實證結果發現，貸款成數與違約風險呈現顯著正相關，貸款成數增加，邊際影響呈遞增情形，違約率隨之遞增，而違約預期損失額亦同時上升。保險公司因預期損失額增加，為維持保費收入得以支付預期損失，其保險費率將明顯提升。故實施房屋貸款保證保險，因借款者信用增強而提高之貸款成數，將增加違約機率並對保險費率產生直接變動。 / Mortgage insurance system may transfer part of the default risk to insurance companies. However, the implementation of mortgage insurance system, on increasing loan to value ratio, the resulting increase default risk. And literatures estimate the expected loss without the default data, there will be misjudge. Our study constructs the binary logistic regression model and survival analysis to estimate the mortgage default behavior, and compare the data between the model fit and the predictive power. Analyzes the effect of loan to value ratio on the marginal probability of default rate. Furthermore, assess the financial institutions in the risk of default due to loan to value ratio changes. According to the estimated default rate data, we employ the mortgage insurance rate structural model to calculate the expected amount of loss and the changes in premium rates. Empirical results found loan to value ratio have a significant positive effect on borrowers’ default. Loan to value ratio increase, the marginal effect progressively increase, along with increasing default rates and expected default losses. Due to the ascendant expected loss, insurance companies increase premiums to cover the expected loss, the premium rate will be significantly improved. Therefore, the implementation of mortgage insurance, credit enhancement for the borrower to improve loan to value ratio, will increase the probability of default and insurance rates.

本研究所使用違約機率（Probability of Default, 以下簡稱PD）的預測方法為Robust Logistic Regression（穩健羅吉斯迴歸），本研究發展且應用這個方法是基於下列兩個觀察：1. 極端值常常出現在橫剖面資料，而且對於實證結果往往有很大地影響，因而極端值必須要被謹慎處理。2. 當使用Logit Model（羅吉斯模型）估計違約率時，卻忽略極端值。試圖不讓資料中的極端值對估計結果產生重大的影響，進而提升預測的準確性，是本研究使用Logit Model並混合Robust Regression（穩健迴歸）的目的所在，而本研究是第一篇使用Robust Logistic Regression來進行PD預測的研究。 變數的選取上，本研究使用Z-SCORE模型中的變數，此外，在考慮公司的營收品質之下，亦針對公司的應收帳款週轉率而對相關變數做了調整。 本研究使用了一些信用風險模型效力驗證的方法來比較模型預測效力的優劣，本研究的實證結果為：針對樣本內資料，使用Robust Logistic Regression對於整個模型的預測效力的確有提升的效果；當營收品質成為模型變數的考量因素後，能讓模型有較高的預測效力。最後，本研究亦提出了一些重要的未來研究建議，以供後續的研究作為參考。 / The method implemented in PD calculation in this study is “Robust Logistic Regression”. We implement this method based on two reasons: 1. In panel data, outliers usually exist and they may seriously influence the empirical results. 2. In Logistic Model, outliers are not taken into consideration. The main purpose of implementing “Robust Logistic Regression” in this study is: eliminate the effects caused by the outliers in the data and improve the predictive ability. This study is the first study to implement “Robust Logistic Regression” in PD calculation. The same variables as those in Z-SCORE model are selected in this study. Furthermore, the quality of the revenue in a company is also considered. Therefore, we adjust the related variables with the company’s accounts receivable turnover ratio. Some validation methodologies for default risk models are used in this study. The empirical results of this study show that: In accordance with the in-sample data, implementing “Robust Logistic Regression” in PD calculation indeed improves the predictive ability. Besides, using the adjusted variables can also improve the predictive ability. In the end of this study, some important suggestions are given for the subsequent studies.