Techn. Univ., Diss/2004--Darmstadt, 2003.

Thesis (Ph.D.)--University of Wollongong, 2007. / Typescript. Includes bibliographical references: leaf 168-189.

Thesis (Ph. D.)--Columbia University, 1941. / Lithoprinted. Vita. Bibliography: p. 257-263.

Thesis (doctoral)--Technische Universität, Darmstadt, 2003/2004. / Includes bibliographical references (p. 274-290) and index.

ABSTRACT “Almost all places are in trouble, but some are in more trouble than others" Kotler, Haider & Rein (1993) Kotler, Haider & Rein (1993) contend that all places are in trouble now, or will be in the near future. The onset of globalisation of the world's economy, country political dynamics and the accelerating pace of technological changes are some of the forces that require all places to learn how to compete on the world arena. Porter (1990) states that the framework for understanding a company’s sources of competitive advantage can be extended to the level of nations. It is basically concerned with the question as to why some nations succeed in global competition when others fail. Nations must learn how to think more like businesses if they are to survive and should begin by identifying their competitive advantages and building on them. As countries compete for inward investment, tourism and export of goods and services- success or failure can accurately be chartered, and questions of reputation, image, identity and hence marketing and branding become central to the competitive edge (Olins, 1999). Faced with the challenge of a negative image, a country must adopt a proactive stance to correct this image. This is where the question of country branding comes in. Branding a country for many is misconstrued and interpreted to simply mean designing a new logo for their country and possibly a slogan to go underneath it. However country-banding proponents highlight that there is a difference between nation branding and tourism promotion. It helps even less that there are so many communications agencies that perhaps frustrated by lack of pure strategy capacity to sell to governments, have fallen into the habit of i Sibonokuhle GUMPO - 34462481 pandering to this misconception and simply selling logos and slogans to any government prepared to buy them (Anholt, 2003). However faced with the urgent need to address the crippling impact of a negative image, countries like Zimbabwe cannot simply wait and expect things to turn out for the better. Kotler et al (1993) stress that places are not able to respond to negative images concerning their nations as quickly as negative perceptions are built, be it through media, word of mouth or other channels. As a result the importance of a pro-active response cannot be overemphasized. This study explores the current negative image of Zimbabwe and tries to define the root or source of this negative image. Having defined or spelt out what is thought to be the problem, the researcher than explores possible ways of how the stakeholders of Zimbabwe can rebrand their country reflecting on known success stories. Kotler et al (1993) contend that the central tenet of marketing places is that in spite of the powerful internal and external forces that buffet them, places have within their collective resources and people the capacity to improve their relative competitive positions. Zimbabweans in general believe that their situation has been sensationalised by the media and is not a reflection of what is on the ground. By adopting a proactive stance in rebranding their country, Zimbabweans will perhaps finally realise that when it comes to image, “being in possession of the truth is not enough, the truth has to be sold” (Anholt,all places are in trouble now, or will be in the near future. The onset of globalisation of the world's economy, country political dynamics and the accelerating pace of technological changes are some of the forces that require all places to learn how to compete on the world arena. Porter (1990) states that the framework for understanding a company’s sources of competitive advantage can be extended to the level of nations. It is basically concerned with the question as to why some nations succeed in global competition when others fail. Nations must learn how to think more like businesses if they are to survive and should begin by identifying their competitive advantages and building on them. As countries compete for inward investment, tourism and export of goods and services- success or failure can accurately be chartered, and questions of reputation, image, identity and hence marketing and branding become central to the competitive edge (Olins, 1999). Faced with the challenge of a negative image, a country must adopt a proactive stance to correct this image. This is where the question of country branding comes in. Branding a country for many is misconstrued and interpreted to simply mean designing a new logo for their country and possibly a slogan to go underneath it. However country-banding proponents highlight that there is a difference between nation branding and tourism promotion. It helps even less that there are so many communications agencies ABSTRACT “Almost all places are in trouble, but some are in more trouble than others" Kotler, Haider & Rein (1993) Kotler, Haider & Rein (1993) contend that all places are in trouble now, or will be in the near future. The onset of globalisation of the world's economy, country political dynamics and the accelerating pace of technological changes are some of the forces that require all places to learn how to compete on the world arena. Porter (1990) states that the framework for understanding a company’s sources of competitive advantage can be extended to the level of nations. It is basically concerned with the question as to why some nations succeed in global competition when others fail. Nations must learn how to think more like businesses if they are to survive and should begin by identifying their competitive advantages and building on them. As countries compete for inward investment, tourism and export of goods and services- success or failure can accurately be chartered, and questions of reputation, image, identity and hence marketing and branding become central to the competitive edge (Olins, 1999). Faced with the challenge of a negative image, a country must adopt a proactive stance to correct this image. This is where the question of country branding comes in. Branding a country for many is misconstrued and interpreted to simply mean designing a new logo for their country and possibly a slogan to go underneath it. However country-banding proponents highlight that there is a difference between nation branding and tourism promotion. It helps even less that there are so many communications agencies that perhaps frustrated by lack of pure strategy capacity to sell to governments, have fallen into the habit of i Sibonokuhle GUMPO - 34462481 pandering to this misconception and simply selling logos and slogans to any government prepared to buy them (Anholt, 2003). However faced with the urgent need to address the crippling impact of a negative image, countries like Zimbabwe cannot simply wait and expect things to turn out for the better. Kotler et al (1993) stress that places are not able to respond to negative images concerning their nations as quickly as negative perceptions are built, be it through media, word of mouth or other channels. As a result the importance of a pro-active response cannot be overemphasized. This study explores the current negative image of Zimbabwe and tries to define the root or source of this negative image. Having defined or spelt out what is thought to be the problem, the researcher than explores possible ways of how the stakeholders of Zimbabwe can rebrand their country reflecting on known success stories. Kotler et al (1993) contend that the central tenet of marketing places is that in spite of the powerful internal and external forces that buffet them, places have within their collective resources and people the capacity to improve their relative competitive positions. Zimbabweans in general believe that their situation has been sensationalised by the media and is not a reflection of what is on the ground. By adopting a proactive stance in rebranding their country, Zimbabweans will perhaps finally realise that when it comes to image, “being in possession of the truth is not enough, the truth has to be sold” (Anholt, / Graduate School of Business Leadership / MBL

Cette thèse est divisée en deux sections. La première section adresse la question sur les conséquences des interventions des politiques budgétaires sur l'économie et la deuxième section traite de la problématique de la liquidité des titres européens de la dette souveraine pendant la récente crise financière, l'effet d'un choc de liquidité sur ces titres et les conséquences des réponses politiques. Le premier chapitre étudie l'impact d'un choc de politique budgétaire discrétionnaire sur l'activité économique et d'autres variables macroéconomiques en utilisant une approche alternative à deux étapes pour l'identification d'un choc budgétaire. Le deuxième chapitre analyse conjointement les effets d'une combinaison de chocs de politique fiscale et monétaire sur les variables macroéconomiques et financières, en utilisant un modèle de Time- V arying Parameters Factor Augmented Vector (TVP-F A V AR). Le troisième chapitre étudie le rôle des titres de la dette souveraine comme collatéral dans le marché interbancaire . En particulier, dans le marché dès pensions livrées, on montre comment une augmentation des marges initiales des pensions livrées, peut représenter un canal dans la transmission des crises bancaires aux crises de la dette souveraine dans les pays de la périphérie de la zone euro. Une augmentation des marges initiales des pensions livrées, qui ont comme collatéraux les titres de la dette souveraine peut être modélisée comme un choc de liquidité sur les titres de la dette souveraine. Le quatrième chapitre analyse l'impact de ce choc dans un modèle stochastique dynamique d'équilibre général (DSGE) avec frictions financières et analyse les conséquences des mesures économiques non-conventionnelles pour restaurer la liquidité dans les marchés financiers. / This dissertation is divided in two sections. The first section addresses the question of the consequences of fiscal policy interventions on the economy and the second section analyzes the issue of the liquidity of European Government bonds during the recent financial crisis, the effect ofliquidity shock on these securities and consequences ofpolicy responses. The frrst chapter studies the impact of a discretionary government spending shock on economic activity and other macroeconomic variables by using an alternative two-step procedure for the identification of the govemment spending shock. The second chapter analyzes the effects of a combination of fiscal and monetary policy shocks on macroeconomic and financial variables using a Time Varying Parameters Factor Augmented VAR (TVP-FA VAR) mode!. The third chapter investigates the European market of repurchase agreements and shows that government bonds represent a key fraction of the collateral in these transactions. lt also examines the effects of a rise in haircuts on the value of govemment bonds and shows that this mechanism may represent a channel in the transmission mechanism of banking and sovereign-debt crises in the periphery of the Eurozone. Following the empirical findings of the third chapter, the last chapter proposes a DSGE model with financial frictions to assess the impact of a negative liquidity shock and the consequences ofunconventional policy.

Le but de cette thèse est d’approfondir les connaissances académiques sur les variations jointes des actifs financiers à haute fréquence en les analysant sous un point de vue novateur. Nous tirons profit d’une base de données de prix tick-by-tick pour mettre en lumière de nouveaux faits stylises sur la corrélation haute fréquence, et également pour tester la validité empirique de modèles multivariés. Dans le chapitre 1, nous discutons des raisons pour lesquelles la corrélation haute fréquence est d’une importance capitale pour le trading. Par ailleurs, nous passons en revue la littérature empirique et théorique sur la corrélation à de petites échelles de temps. Puis nous décrivons les principales caractéristiques du jeu de données que nous utilisons. Enfin, nous énonçons les résultats obtenus dans cette thèse. Dans le chapitre 2, nous proposons une extension du modèle de subordination au cas multivarié. Elle repose sur la définition d’un temps événementiel global qui agrège l’activité financière de tous les actifs considérés. Nous testons la capacité de notre modèle à capturer les propriétés notables de la distribution multivariée empirique des rendements et observons de convaincantes similarités. Dans le chapitre 3, nous étudions les relations lead/lag à haute fréquence en utilisant un estimateur de fonction de corrélation adapte aux données tick-by-tick. Nous illustrons sa supériorité par rapport à l’estimateur standard de corrélation pour détecter le phénomène de lead/lag. Nous établissons un parallèle entre le lead/lag et des mesures classiques de liquidité et révélons un arbitrage pour déterminer les paires optimales pour le trading de lead/lag. Enfin, nous évaluons la performance d’un indicateur basé sur le lead/lag pour prévoir l’évolution des prix à court terme. Dans le chapitre 4, nous nous intéressons au profil saisonnier de la corrélation intra-journalière. Nous estimons ce profil sur quatre univers d’actions et observons des ressemblances frappantes. Nous tentons d’incorporer ce fait stylise dans un modèle de prix tick-by-tick base sur des processus de Hawkes. Le modèle ainsi construit capture le profil de corrélation empirique assez finement, malgré sa difficulté à atteindre le niveau de corrélation absolu. / This thesis aims at providing insight into comovements of financial assets at high frequency from an original point of view. We take advantage of a database of tick-by-tick prices to bring to light new stylized facts on high frequency correlation as well as to check the empirical validity of multivariate modelling frameworks. In chapter 1, we elaborate on the reasons why high frequency correlation is of the utmost importance for trading purposes. We also briefly review the empirical and theoretical literature on correlation at small time scales. Then, we describe the main features of the data set we use. Finally, we enunciate the results obtained in this thesis. In chapter 2, we suggest a way of extending the subordination modelling to the multivariate case. This relies on the definition of a global event time that merges the trading activity of all assets under consideration. We test the ability of our model to capture salient features of the empirical multivariate probability distribution of returns and find a convincing agreement. In chapter 3, we study high frequency lead/lag relationships using a suitable cross-correlation estimator for tick-by-tick data. We show its superiority over the classical correlation estimator in detecting lead/lag patterns. We relate lead/lag to standard liquidity measures and exhibit a trade-off to find optimal pairs for lead/lag trading. Finally, we evaluate the performance of a lead/lag indicator in forecasting the short-term evolution of prices. In chapter 4, we focus on the intraday correlation seasonal pattern. We estimate this pattern over four universes of stocks and observe striking similarities. We attempt to incorporate this stylized fact into a tick-by-tick price model based upon Hawkes processes. The resulting model captures the empirical profile of correlation quite well, though it doesn’t match the absolute level of correlation.

The recent financial crisis has brought to the fore the need to better understand systemic risk, that is, the risk of collapse of a large part of the financial system and its potential effects on the real economy. In this thesis, we argue that a proper assessment of systemic risk must include an analysis of the network of interdependencies that exists between the different financial institutions. In fact, today's level of financial interconnectedness between and among markets has proven to have ambiguous effects. On the one hand, a highly connected system allows to diversify risk at the micro level. On the other hand, too much interdependencies provide various paths for contagion to take place and propagate at the macro level. In what follows, we analyze financial markets as networks of interactions and dependencies between financial agents. Through this lens, we investigate three major aspects: (i) how the structure of financial networks can amplify or mitigate the propagation of financial distress, (ii) what are the implications for macro-prudential regulation and (iii) which patterns of interactions characterize real financial networks.We start out by delivering a stability analysis of a network model of interbank contagion that accounts for panics and bank runs. We identify the effects of market architecture, banks' capital ratios, market liquidity and shocks. Our results show that no single network architecture is always superior to others. In particular, highly concentrated networks can both be the most robust and the most fragile depending on other market characteristics, mainly, liquidity.We then move on to tackle issues related to the building of regulatory frameworks that adequately account for the effects of financial interdependencies. We propose a new methodology to compute individual and systemic probabilities of default and show that certain network characteristics give rise to uncertainty. More precisely, we find that network cycles are responsible for the emergence of multiple equilibria even in the presence of complete knowledge. In turn, multiple equilibria give rise to uncertainty for the regulator in the determination of default probabilities. We also quantify the effects of network structures, leverage, volatility and correlations.Having introduced a way to overcome multiplicity, we deliver a method that quantifies the price of complexity in financial markets based on the above mentioned model. This method consists of determining the scope of possible levels of systemic risk that can be obtained when some parameters are subject to small deviations from their true value. The results show a price to the interconnected nature of credit markets even when the equilibrium is unique: small errors can lead to large mistakes in measuring the likelihood of systemic default. Extending the model to account for derivative contracts, we show that error effects increase dramatically as more types of contracts are present in the system. While there is an intuition for such phenomenon, our framework formalizes the idea and quantifies its determinants.In the last part of this thesis, we contribute to the quantitative analysis of real financial networks. We start with a temporal network analysis of one of the major national interbank markets, that is, the German interbank market. We report on the structural evolution of two of the most important over-the-counter markets for liquidity: the interbank market for credit and for derivatives. We find that the majority of interactions is concentrated onto a set of few market participants. There also exists an important correlation between the borrowing and lending activities for each bank in terms of numbers of counterparties. In contrast with other works, we find little impact of the 2008 crisis on the structure of the credit market. The derivative market however exhibits a peak of concentration in the run up to the crisis. Globally, both markets exhibit large levels of stability for most of the network metrics and high correlation amongst them.Finally, we analyze how banks interact with the real economy by investigating the network of loans from banks to industries in Japan. We find evidence of a particular structure of interactions resulting from the coexistence of specific strategies both on the lending side and the borrowing side: generalist agents and specialist agents. Generalist banks have a diversified portfolio (i.e. they provide liquidity to almost all industries) while specialist banks focus their activity on a narrow set of industries. Similarly, generalists industries obtain credit from all banks while specialist industries have a restricted number of creditors. Moreover, the arrangement of interactions is such that specialists tend to only interact with generalists from the other side. Our model allows to structurally characterize highly persistent, and economically meaningful, sets of generalists and specialists. We further provide an analysis of the factors that predict whether a given bank or industry is a generalist. We show that size is an important determinant, both for banks and industries, but we also highlight additional relevant factors. Finally, we find that generalist banks tend to be less vulnerable. Hence, how banks position themselves in the network has important implications for their risk profile. Overall the results presented in this thesis highlight the complex role played by financial interlinkages. Therefore, they demonstrate the need to embed the network dimension in the regulatory framework to properly assess the stability profile of financial systems. Such findings are relevant for both theoretical modeling and empirical investigations. We believe that they also shed light on crucial aspects of systemic risk relevant for policy making and regulation of today's complex financial systems. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The goal of this thesis is to study the two key aspects of complexity of the financial system: interconnectedness and nonlinear relationships. In Chapter 1, I contribute to the literature that focuses on modelling the nonlinear relationship between variables at the extremes of their distribution. In particular, I study the nonlinear relationship between stock prices and short selling. Whereas most of the academic literature has focused on measuring the relationship between short selling and asset returns on average, in Chapter 1, I focus on studying the relationship that arises in the extremes of the two variables. I show that the association between financial stock prices and short selling can become extremely strong under exceptional circumstances, while at the same time being weak in normal times. The tail relationship is stronger for small cap firms, a result that is intuitively in line with the empirical findings that stocks with lower liquidity are more price-sensitive to short selling. Finally, results show that the adverse tail correlation between increases in short selling and declines in stock prices was not always lower during the ban periods, but had declined markedly towards the end of the analysis window. Such results cast doubts about the effectiveness of bans as a way to prevent self-reinforcing downward price spirals during the crisis. In Chapter 2, I propose a measure of interconnectedness that takes into account the time-varying nature of connections between financial institutions. Here, the parameters underlying comovement are allowed to evolve continually over time through permanent shifts at every period. The result is an extremely flexible measure of interconnectedness, which uncovers new dynamics of the US financial system and can be used to monitor financial stability for regulatory purposes. Various studies have combined statistical measures of association (e.g. correlation, Granger causality, tail dependence) with network techniques, in order to infer financial interconnectedness (Billio et al. 2012; Barigozzi and Brownlees, 2016; Hautsch et al. 2015). However, these standard statistical measures presuppose that the inferred relationships are time-invariant over the sample used for the estimation. To retrieve a dynamic measure of interconnectedness, the usual approach has been to divide the original sample period into multiple subsamples and calculate these statistical measures over rolling windows of data. I argue that this is potentially unsuitable if the system studied is time-varying. By relying on short subsamples, rolling windows lower the power of inference and induce dimensionality problems. Moreover, the rolling window approach is known to be susceptible to outliers because, in small subsamples, these have a larger impact on estimates (Zivot and Wang, 2006). On the other hand, choosing longer windows will lead to estimates that are less reactive to change, biasing results towards time-invariant connections. Thus, the rolling window approach requires the researcher to choose the window size, which involves a trade-off between precision and flexibility (Clark and McCracken, 2009). The choice of window size is critical and can lead to different results regarding interconnectedness. The major novelty of the framework is that I recover a network of financial spillovers that is entirely dynamic. To do so, I make the modelling assumption that the connection between any two institutions evolves smoothly through time. I consider this assumption reasonable for three main reasons. First, since connections are the result of many financial contracts, it seems natural that they evolve smoothly rather than abruptly. Second, the assumption implies that the best forecast of a connection in the future is the state of that connection today. This is consistent with the notion of forward-looking prices. Third, the assumption allows for high flexibility and for the data to speak for itself. The empirical results show that financial interconnectedness peaked around two main events: the Long-Term Capital Management crisis of 1998 and the great financial crisis of 2008. During these two events, I found that large banks and broker/dealers were among the most interconnected sectors and that real estate companies were the most vulnerable to financial spillovers. At the individual financial institution level, I found that Bear Stearns was the most vulnerable financial institution, however, it was not a major propagator, and this might explain why its default did not trigger a systemic crisis. Finally, I ranked financial institutions according to their interconnectedness and I found that rankings based on the time-varying approach were more stable than rankings based on other market-based measures (e.g. marginal expected short fall by Acharya et al. (2012) and Brownlees and Engle (2016)). This aspect is significant for policy makers because highly unstable rankings are unlikely to be useful to motivate policy action (Danielsson et al. 2015; Dungey et al. 2013). In Chapter 3, rather than assuming interconnectedness as an exogenous process that has to be inferred, as is done in Chapter 2, I model interconnectedness as an endogenous function of market dynamics. Here, I take interconnectedness as the realized correlation of asset returns. I seek to understand how short selling can induce higher interconnectedness by increasing the negative price pressure on pairs of stocks. It is well known that realized correlation varies continually through time and becomes higher during market events, such as the liquidation of large funds. Most studies model correlation as an exogenous stochastic process, as is done, for example, in Chapter 2. However, recent studies have proposed to interpret correlation as an endogenous function of the supply and demand of assets (Brunnermeier and Pedersen, 2005; Brunnermeier and Oehmke, 2014; Cont and Wagalath, 2013; Yang and Satchell, 2007). Following these studies, I analyse the relationship between short selling and correlation between assets. First, thanks to new data on public short selling disclosures for the United Kingdom, I connect stocks based on the number of common short sellers actively shorting them. I then analyse the relationship between common short selling and excess correlation of those stocks. To this end, I measure excess correlation as the monthly realized correlation of four-factor Fama and French (1993) and Carhart (1997) daily returns. I show that common short selling can predict one-month ahead excess correlation, controlling for similarities in size, book-to-market, momentum, and several other common characteristics. I verify the confirm the predictive ability of common short selling out-of-sample, which could prove useful for risk and portfolio managers attempting to forecast the future correlation of assets. Moreover, I showed that this predictive ability can be used to establish a trading strategy that yields positive cumulative returns over 12 months. In the second part of the chapter I concentrate on possible mechanisms that could give rise to this effect. I focus on three, non-exclusive, mechanisms. First, short selling can induce higher correlation in asset prices through the price-impact mechanism (Brunnermeier and Oehmke, 2014; Cont and Wagalath, 2013). According to this mechanism, short sellers can contribute to price declines by creating sell-order imbalances i.e. by increasing excess supply of an asset. Thus, short selling across several stocks should increase the realized correlation of those stocks. Second, common short selling can be associated with higher correlation if short sellers are acting as voluntary liquidity providers. According to this mechanisms, short sellers might act as liquidity providers in times of high buy-order imbalances (Diether et al. 2009b). In this cases, the low returns observed after short sales might be compensations to short sellers for providing liquidity. In a multi-asset setting, this mechanism would result in short selling being associated with higher correlation mechanism. Both above-mentioned mechanisms deliver a testable hypothesis that I verify. In particular, both mechanisms posit that the association between short selling and correlation should be stronger for stocks which are low on liquidity. For the first mechanism, the price impact effect should be stronger for illiquid stocks and stocks with low market depth. For the liquidity provision mechanism, the compensation for providing liquidity should be higher for illiquid stocks. The empirical results cannot confirm that uncovered association between short selling and correlation is stronger for illiquid stocks, thus not supporting the price-impact and liquidity provision hypothesis. I thus examine a third possible mechanism that could explain the uncovered association between short selling and correlation i.e. the informative trading mechanism. Short sellers have been found to be sophisticated market agents which can predict future returns (Dechow et al. 2001). If this is indeed the case, then short selling should be associated with higher future correlation. I found that informed common short selling i.e. common short selling that is linked to informative trading, was strongly associated to future excess correlation. This evidence supports the informative trading mechanism as an explanation for the association between short selling and correlation. In order to further verify this mechanism, I checked if informed short selling takes place in the data, whilst controlling for several of the determinants of short selling, including short selling costs. The results show evidence of both informed and momentum-based non-informed short selling taking place. Overall, the results have several policy implications for regulators. The results suggest that the relationship between short selling and future excess correlation is driven by informative short selling, thus confirming the sophistication of short sellers and their proven importance for market efficiency and price informativeness (Boehmer and Wu, 2013). On the other hand, I could not dismiss that also non-informative momentum-based short selling is taking place in the sample. The good news is that I did not find evidence of a potentially detrimental price-impact effect of common short selling for illiquid stock, which is the sort of predatory effect that regulators often fear. / Doctorat en Sciences économiques et de gestion / info:eu-repo/semantics/nonPublished

En quoi l'absence d'intérêts économiques communs entre les pays membres de l'OCDE affaiblit-elle les nouvelles législations internationales basées sur le Soft Law en vue de lutter contre l'opacité financière et fiscale des centres financiers offshore ? L'optimisation fiscale consiste à utiliser les règles de droit pour réduire en toute légalité sa charge fiscale. Mais la frontière entre l'optimisation fiscale et l'évasion fiscale est ténue pour ne pas dire perméable. De plus en plus, les notions d'optimisation fiscale et de fraude fiscale ne font plus qu'une, tant les règles de droit sont facilement contournables et ses limites aisément franchissables. Ce phénomène est tout particulièrement avéré sur le plan de la fiscalité internationale. La problématique de cette thèse met en lumière les difficultés du Soft Law à réguler les centres financiers offshore, tant l'absence d'intérêts (économiques) communs semble flagrante entre les pays anglo-saxons et l'Europe continentale sur la question. Or l'intérêt commun (qu'il soit économique, culturel, sécuritaire, environnemental) constitue la clef de voûte du succès d'une législation basée sur le Soft Law à l'international. L'intérêt commun paraît inexistant voire inaccessible en matière de lutte contre l'optimisation fiscale, dès lors que celle-ci vise principalement à protéger le modèle social de l'état providence des pays d'Europe continentale. Une dichotomie de taille à l'heure où les pays anglo-saxons s'en écartent toujours plus. / How does the lack of shared economic interests among OECD member countries weaken new international laws-which are based on soft law-that aim to contribute to the fight against the financial and fiscal opacity of offshore financial centers? Tax optimization involves using the rules of law to legally reduce a tax burden. But the line that separates tax optimization and tax evasion is tenuous and one could even say porous al best. Increasingly, it indeed appears that the issues of tax optimization and tax-fraud are becoming one, as the rules of law can be easily circumvented and the limits easily crossed. This phenomenon is particularly evident in the field of international taxation. This thesis deals precisely with the issue of difficulties of Soft Law in regulating offshore financial centers. Indeed, the absence of common economic interests is blatant between the Anglo-Saxon countries and continental Europe on this issue, thus finding a common interest (that could be economic, cultural, environmental or security-related) appears to be key to the success of legislation based on Soft Law internationally. The common interest seems unattainable when it comes to combating tax optimization, since the main aim is to protect the social model of the welfare state in continental European countries. A dichotomy of size at the time when the Anglo-Saxon countries are increasingly lacking in such a model.