O objetivo deste trabalho consiste em identificar a existência de contágio financeiro utilizando a metodologia de redes bayesianas. Além da rede bayesiana, a análise da interdependência de mercados internacionais em períodos de crises financeiras, ocorridas entre os anos 1996 e 2009, foi modelada com outras duas técnicas - modelos GARCH multivariados e de Cópulas, envolvendo países nos quais foi possível avaliar seus efeitos e que foram objetos de estudos similares na literatura. Com os períodos de crise bem definidos e metodologia calcada na teoria de grafos e na inferência bayesiana, executou-se uma análise sequencial, em que as realidades que precediam períodos de crise foram consideradas situações a priori para os eventos (verossimilhanças). Desta combinação resulta a nova realidade (a posteriori), que serve como priori para o período subsequente e assim por diante. Os resultados apontaram para grande interligação entre os mercados e diversas evidências de contágio em períodos de crise financeira, com causadores bem definidos e com grande respaldo na literatura. Ademais, os pares de países que apresentaram evidências de contágio financeiro pelas redes bayesianas em mais períodos de crises foram os mesmos que apresentaram os mais altos valores dos parâmetros estimados pelas cópulas e também aqueles cujos parâmetros foram mais fortemente significantes no modelo GARCH multivariado. Assim, os resultados obtidos pelas redes bayesianas tornam-se mais relevantes, o que sugere boa aderência deste modelo ao conjunto de dados utilizados neste estudo. Por fim, verificou-se que, após as diversas crises, os mercados estavam muito mais interligados do que no período inicialmente adotado. / This work aims to identify the existence of financial contagion using a metodology of Bayesian networks. Besides Bayesian networks, the analysis of the international markets\' interdependence in times of financial crises, occurred between 1996 and 2009, was modeled using two other techniques - multivariate GARCH models and Copulas models, involving countries in which its effects were possible to assess and which were subject to similar studies in the literature. With well-defined crisis periods and a metodology based on graph theory and Bayesian inference, a sequential analysis was executed, in which the realities preceding periods of crisis were considered to be prior situations to the events (likelihood). From this combination results the new posterior reality, which serves as a prior to the subsequent period and so on. The results pointed to a large interconnection between markets and several evidences of contagion in times of financial crises, with well-defined responsibles and highly supported by the literature. Moreover, the pairs of countries that show evidence of financial contagion by Bayesian networks in over periods of crises were the same as that presented the highest values of the parameters estimated by copulas and the most strongly significant parameters in the multivariate GARCH model. Thus, the results obtained by Bayesian networks become more relevant, suggesting good adherence of the model to the data set used in this study. Finally, it was found that after the various crises, the markets were much more connected.

Thesis advisor: Matthew O. Jackson / In this dissertation, I focus on networks in macroeconomics and finance. In Chapter 1, I develop a theoretical model of rescue of distressed financial institutions. I study rescues in a coalition formation framework, which provides new insights into the financial contagion and stability and rescue of systemically important financial institutions. The findings show that the levels of negative shock, bankruptcy costs, interbank obligations of each financial firm and the topology of the interbank network all together determine financial firms’ contributions in rescues, where government assistance in rescues is not required in certain types of network structures. In Chapter 2, which is a joint work with Matthew O. Jackson, we study the impacts of sector level technological changes on wage inequality and GDP growth in production networks. Our results show that the macroeconomic implications of sector level technological changes depend on additional factors than the input-output structure such as type of the intermediate good (e.g., substitutes for labor vs complements to labor), task weights in production processes and labor supply. Chapter 1. I model bank rescues in a setting where banks hold each other’s financial instruments creating a network of financial linkages. Costly bankruptcies reduce interbank payments, which creates incentives for rescues by other banks. Accordingly, I analyze the sources of inefficiencies in bank rescues and show that the social welfare is maximized if regulators promote financial networks that are evenly connected (without disconnectedness/clustering) and have intermediate levels of interbank liabilities at bank level. Such networks maximize banks’ total contributions to the rescue of a distressed bank hit by a relatively small negative shock, but also ensure that banks do not fail sequentially like dominos when a bank hit by a large shock does actually fail. The results also provide a rationale for why some systemically important banks were not rescued in 2007-2008. In the model, a social welfare maximizing government assists the rescues designed to prevent the potential contagious failures and maintain financial stability instead of assisting the rescue of a bank that is hit by a large shock. Chapter 2. We study the impact of technological change on wage inequality and GDP growth in production networks. We do this in a simple model that contrasts the effects of changes in intermediate goods that substitute for labor with those that complement labor. Technological changes in intermediate goods that complement labor result in increased GDP and do not change relative wages. Technological changes in intermediate goods that substitute for (low-skilled) labor involve three phases: pre-automation, transition to automation, and post-automation. During the transition phase, technological changes in such intermediate good lead to increased wage inequality and relatively smaller increases in GDP than comparable changes in complementary goods. In addition, our results show that firm-level weights of tasks performed by different types of labor play key roles in macroeconomic network consequences of interconnectedness. / Thesis (PhD) — Boston College, 2018. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Economics.

Cette thèse est articulée autour de trois risques financiers que sont : la liquidité, la contagion et le risque systémique. Ces derniers sont au centre de toutes les attentions depuis la crise de 2007-08 et resteront d’actualité à la vue des évènements que rencontrent les marchés financiers. Le premier chapitre de cette thèse présente un facteur de liquidité de financement obtenu par l’interprétation d’un phénomène de contagion en termes de risque de liquidité de marché. Nous proposons dans le second chapitre, une méta-mesure de cette liquidité de marché. Cette dernière tient compte de l’ensemble des dimensions présentes dans la définition de la liquidité en s’intéressant à la dynamique de plusieurs mesures de liquidité simultanément. L’objectif du troisième chapitre est de présenter une modélisation des rendements du marché permettant la prise en compte de la liquidité de financement dans l’estimation de la DCoVaR. Ainsi, ce travail propose une nouvelle mesure du risque systémique ayant un comportement contracyclique. Pour finir, nous nous intéressons à l’hypothèse de non-linéarité de la structure de dépendance entre les rendements de marché et ceux des institutions financières. Au cœur de la mesure du risque systémique, cette hypothèse apparait contraignante puisqu’elle n’a que peu d’impact sur l’identification des firmes les plus risquées mais peut compliquer considérablement l’estimation de ces mesures. / The aim of this thesis is to improve the management of financial risks through the employment of econometric methods. We focus on liquidity (market and funding), contagion and systemic risk, which have attracted a particularly large interest in the last years of financial turmoil. Firstly, we construct a funding liquidity factor based on the contagion effects that market liquidity risks encounter. This procedure can be useful to provide a better management of the liquidity mismatch among the assets and liabilities of a fund. Secondly, we propose a meta-measure of liquidity which incorporates multiple liquidity measures through the use of a conditional correlation model. As a result, we are able to detect drastic liquidity problems by using a single measure. Thirdly, we propose a new modeling framework for financial returns by adding an extra component related to funding liquidity to the standard DCoVaR model. In this way we obtain a countercyclical measure of systemic risk. Finally, we study to which extent a change in the estimation method affects the identification of systemically relevant Financial Institutions. In particular, the most popular measures aim at capturing the nonlinearity of the dependence structure between financial firms and market returns. We show, however, that similar results can be obtained by simply assuming a linear dependence, which can also largely simplify the estimation.

As crises financeiras são processos de perdas decorrentes do mecanismo do mercado financeiro. Elas afetam as instituições do sistema financeiro e por meio do processo de contágio se espalham por ele, algumas vezes analogamente ao efeito dominó. Este processo pode levar muitas instituições financeiras saudáveis a se tornarem insolventes. Isso acontece porque os agentes econômicos estão interligados por meio de relações contratuais e se tornam dependentes uns aos outros. O risco sistêmico pode ser entendido como o risco de uma grande perda em um sistema. O presente trabalho tem como objetivo utilizar as propriedades de um modelo de contágio, proposto para estudar os efeitos da propagação de crises financeiras, bem como a mensuração do risco sistêmico no sistema interbancário. Este problema foi investigado considerando três diferentes topologias de rede: Erdös-Rényi, Livre de Escala (ou Scale-Free) e Interbancária Empírica. A escolha destas topologias foi pelo fato de que duas delas - Livre de Escala e Interbancária Empírica - podem emular o sistema bancário real e a de Erdös-Rényi ter sido utilizada em diversos modelos da literatura. Cada nó representa um banco que possui balanço patrimonial constituído de passivos (patrimônio líquido, empréstimos e depósitos) e ativos (empréstimos, títulos e valores mobiliários). Foi analisada a influência da alavancagem do sistema, da probabilidade inicial de default e do número de clusters da rede Interbancária Empírica. O risco sistêmico foi medido utilizando o Indicador de Risco Sistêmico, o Índice de Risco Sistêmico e o VaR Sistêmico. Mostrou-se que as redes Livres de Escala são mais robustas em relação aos ataques aleatórios evitando o aumento da inadimplência. O aumento abrupto do impacto causados pela crise acontece devido ao aumento do grau de alavancagem do sistema. O número de clusters da rede Interbancária Empírica impacta a robustez do sistema. O modelo reproduz o resultado conhecido como Muito Interconectado para Falhar, que é quando bancos mais interconectados oferecem maior risco ao sistema. / The financial crises are processes of losses arising from financial market mechanism. They affect the institutions of the financial system by the process of contagion. Sometimes it is equal to the domino effect. This process can make many healthy financial institutions become insolvents. It happens because economic agents are interconnected through contractual relations and become dependent on each other. Systemic risk can be understood as the risk of a huge loss in a system. The present work aims to study the properties of a contagion model proposed to study the effects of the spread of financial crises, as well as the measurement of systemic risk in the interbank system. This problem was investigated considering three different network topologies: Erdös-Rényi, Scale-Free and Empirical Interbank. The choice of these topologies was made by the fact that two of them - Scale-Free and Empirical Interbank - may emulate the real banking system and Erdös-Rényi has been used in several models in the literature. Each node is a bank and consists on a balance sheet split as liabilities (equity, borrowings and deposits) and assets (lendings, bonds and securities). It was analyzed the influence of the coefficient of leverage, the influence of the initial probability of default and the influence of the number of clusters on the Empirical Interbank. The systemic risk was measured using the Systemic Risk Indicator, Systemic Index and Systemic Value at Risk. It was shown that Scale-Free networks are more robust against random attacks, avoiding increases in the number of defaults. The abrupt increase in the impact caused by the crisis happens due to the increase in coefficient of leverage. The number of clusters on Empirical Interbank network impacts the robustness of the system. The model reproduces the result known as Too Interconnected to Fail, that is, banks more interconnected offer higher risk to the system.

Os mercados financeiros são de extrema relevância para as diversas economias do mundo. Sua efetividade na atração de capitais e investimentos é notória. Atualmente, o fluxo financeiro entre os diversos países é muito intenso, devido ao fenômeno da globalização. Tal situação provoca transmissão de crises financeiras entre diferentes países. Neste contexto, a avaliação de contágio financeiro torna-se um tema bastante relevante. A presente dissertação almejou verificar se houve contágio financeiro da crise americana de 2008 sobre os países do BRIC (Brasil, Rússia, Índia e China). Para tanto, foram utilizadas duas metodologias distintas. Uma delas, devido a Fermanian et al. (2002), foi empregada para estimação não paramétrica das cópulas via kernel. Assim, pode-se averiguar se houve aumento significativo nas medidas de dependência. A outra, desenvolvida por Remillard e Scaillet (2009), é um teste de comparação entre duas cópulas empíricas que investiga se houve mudança na estrutura de dependência no período de crise. Os dois procedimentos metodológicos indicaram a ocorrência de contágio da crise americana de 2008 sobre todos os países do BRIC. / Financial markets are extremely relevant to the world's diverse economies. Its effectiveness in attracting capital and investments is notorious. Currently, the financial flow between the various countries is very intense, due to the phenomenon of globalization. This situation leads to the transmission of financial crises between different countries. In this context, the evaluation of financial contagion becomes a very relevant issue. The present dissertation aimed to verify if there was financial contagion of the 2008 US crisis on the BRIC countries (Brazil, Russia, India and China). For that, two different methodologies were used. One of them, due to Fermanian et al. (2002), was used for non-parametric estimation of copula via kernel. Thus, it can be verified if there was a significant increase in the measures of dependence. The other, developed by Remillard and Scaillet (2009), is a test of comparison between two empirical copulas that investigates if there was a change in the dependency structure in the crisis period. The two methodological procedures indicated the occurrence of contagion of the American crisis of 2008 on all BRIC countries.

Este trabalho testa, através da metodologia de cópulas, a hipótese de contágio financeiro entre ações brasileiras e índices de mercado dos países que deram origem às crises do Terror em 2001, da Argentina em 2001, dos Subpprimes em 2007 e do Débito Soberano Europeu em 2009. Além disso, ainda é feita uma análise dos setores econômicos que mais foram afetados por cada crise. Os testes da crise do Terror apresentaram evidências de contágio do SP500 para 24 ações brasileiras, afetando, principalmente os setores ligado à indústria e à energia. As crises da Argentina e do Débito Soberano Europeu apresentaram evidências de contágio dos índices Merval e Athex para apenas 3 empresas. A crise dos Subprimes apresentou evidências de contágio do SP500 para 35 empresas brasileiras, sendo a maioria ligada aos setores financeiros, de energia e industrial. 7 ações foram afetadas pelas duas crises norteamericanas. Os resultados reforçam a importância da análise de contágio em cada empresa individual, ao invés de utilizar o índice do mercado brasileiro como um todo. / This paper tests, through the copulas methodology, the hypothesis of financial contagion between the individual Brazilian stocks and the market indices of the countries where the crises were originated. The crises analyzed are the Terror crisis in 2001, the Argentina’s crisis in 2001, the Subprime crisis in 2007 and the Sovereign Debt crisis in 2009. In addition to this, the Brazilian economic sectors are examined in order to find out which were most affected by each crisis. The tests of the Terror crisis presented evidence of SP500 contagion to 24 Brazilian stocks, affecting, mainly, sectors related to industry and energy. The Argentina’s crisis and the European Sovereign Debt crisis presented contagion’s evidence of the Merval and Athex indices for only 3 Brazilian companies. The Subprimes crisis presented evidence of SP500 contagion for 35 Brazilian companies, mostly related to the financial, energy and industrial sectors. 7 Brazilian stocks were affected by both American crises. The results reinforce the importance of contagion analysis in each individual company, rather than using the Brazilian market index.

As crises financeiras são processos de perdas decorrentes do mecanismo do mercado financeiro. Elas afetam as instituições do sistema financeiro e por meio do processo de contágio se espalham por ele, algumas vezes analogamente ao efeito dominó. Este processo pode levar muitas instituições financeiras saudáveis a se tornarem insolventes. Isso acontece porque os agentes econômicos estão interligados por meio de relações contratuais e se tornam dependentes uns aos outros. O risco sistêmico pode ser entendido como o risco de uma grande perda em um sistema. O presente trabalho tem como objetivo utilizar as propriedades de um modelo de contágio, proposto para estudar os efeitos da propagação de crises financeiras, bem como a mensuração do risco sistêmico no sistema interbancário. Este problema foi investigado considerando três diferentes topologias de rede: Erdös-Rényi, Livre de Escala (ou Scale-Free) e Interbancária Empírica. A escolha destas topologias foi pelo fato de que duas delas - Livre de Escala e Interbancária Empírica - podem emular o sistema bancário real e a de Erdös-Rényi ter sido utilizada em diversos modelos da literatura. Cada nó representa um banco que possui balanço patrimonial constituído de passivos (patrimônio líquido, empréstimos e depósitos) e ativos (empréstimos, títulos e valores mobiliários). Foi analisada a influência da alavancagem do sistema, da probabilidade inicial de default e do número de clusters da rede Interbancária Empírica. O risco sistêmico foi medido utilizando o Indicador de Risco Sistêmico, o Índice de Risco Sistêmico e o VaR Sistêmico. Mostrou-se que as redes Livres de Escala são mais robustas em relação aos ataques aleatórios evitando o aumento da inadimplência. O aumento abrupto do impacto causados pela crise acontece devido ao aumento do grau de alavancagem do sistema. O número de clusters da rede Interbancária Empírica impacta a robustez do sistema. O modelo reproduz o resultado conhecido como Muito Interconectado para Falhar, que é quando bancos mais interconectados oferecem maior risco ao sistema. / The financial crises are processes of losses arising from financial market mechanism. They affect the institutions of the financial system by the process of contagion. Sometimes it is equal to the domino effect. This process can make many healthy financial institutions become insolvents. It happens because economic agents are interconnected through contractual relations and become dependent on each other. Systemic risk can be understood as the risk of a huge loss in a system. The present work aims to study the properties of a contagion model proposed to study the effects of the spread of financial crises, as well as the measurement of systemic risk in the interbank system. This problem was investigated considering three different network topologies: Erdös-Rényi, Scale-Free and Empirical Interbank. The choice of these topologies was made by the fact that two of them - Scale-Free and Empirical Interbank - may emulate the real banking system and Erdös-Rényi has been used in several models in the literature. Each node is a bank and consists on a balance sheet split as liabilities (equity, borrowings and deposits) and assets (lendings, bonds and securities). It was analyzed the influence of the coefficient of leverage, the influence of the initial probability of default and the influence of the number of clusters on the Empirical Interbank. The systemic risk was measured using the Systemic Risk Indicator, Systemic Index and Systemic Value at Risk. It was shown that Scale-Free networks are more robust against random attacks, avoiding increases in the number of defaults. The abrupt increase in the impact caused by the crisis happens due to the increase in coefficient of leverage. The number of clusters on Empirical Interbank network impacts the robustness of the system. The model reproduces the result known as Too Interconnected to Fail, that is, banks more interconnected offer higher risk to the system.

This thesis consists of three chapters and investigates the issues related to liquidity risk, credit market contagion, and corporate cash holdings. The first chapter is coauthored work with Professor Jay Sa-Aadu and Associate Professor Ashish Tiwari and is titled ‘Market Liquidity, Funding Liquidity, and Hedge Fund Performance.’ The second chapter is sole-authored and is titled ‘Credit Market Contagion and Liquidity Shocks.’ The third chapter is coauthored with Steven Savoy and titled ‘Ambiguity Aversion and Corporate Cash Holdings.’ The first chapter examines the interaction between hedge funds’ performance and their market liquidity risk and funding liquidity risk. Using a 2-state Markov regime switching model we identify regimes with low and high market-wide liquidity. While funds with high market liquidity risk exposures earn a premium in the high liquidity regime, this premium vanishes in the low liquidity states. Moreover, funding liquidity risk, measured by the sensitivity of a hedge fund’s return to the Treasury-Eurodollar (TED) spread, is an important determinant of fund performance. Hedge funds with high loadings on the TED spread underperform low-loading funds by about 0.49% (10.98%) annually in the high (low) liquidity regime, during 1994-2012. The second chapter provides evidence on credit market contagion using CDS index data and identifies the channels through which contagion propagates in credit markets. The results show that funding liquidity and market liquidity are significant channels of contagion during periods with widening credit spreads and adverse liquidity shocks. These results provide support for the theoretical model proposed by Brunnermeier and Pedersen (2009) according to which negative liquidity spirals can lead to contagion across various asset classes. Furthermore, during periods with tightening credit spreads and positive liquidity shocks, the results indicate that a prime broker index and a bank index are important channels contributing to co-movement in credit spreads. This suggests that financial intermediaries play an important role in spreading market rallies across credit markets. The third chapter investigates the link between investors’ ambiguity aversion and precautionary corporate cash holdings. Investors’ ambiguity aversion is measured by the proportion of individual investors in a firm’s investor base who are hypothesized to be more ambiguity averse compared to institutional investors. We show that the value of cash holdings is negatively associated with the extent of ambiguity aversion in a firm’s shareholder base for firms that are financially constrained. Our results also show that financially constrained firms with a higher proportion of ambiguity averse investors hold less cash. These results provide support for models in which ambiguity averse investors dislike the cash holdings of firms, that are held for precautionary reasons to fund long term projects, given that the returns on long term projects are ambiguous.

Este trabalho testa, através da metodologia de cópulas, a hipótese de contágio financeiro entre ações brasileiras e índices de mercado dos países que deram origem às crises do Terror em 2001, da Argentina em 2001, dos Subpprimes em 2007 e do Débito Soberano Europeu em 2009. Além disso, ainda é feita uma análise dos setores econômicos que mais foram afetados por cada crise. Os testes da crise do Terror apresentaram evidências de contágio do SP500 para 24 ações brasileiras, afetando, principalmente os setores ligado à indústria e à energia. As crises da Argentina e do Débito Soberano Europeu apresentaram evidências de contágio dos índices Merval e Athex para apenas 3 empresas. A crise dos Subprimes apresentou evidências de contágio do SP500 para 35 empresas brasileiras, sendo a maioria ligada aos setores financeiros, de energia e industrial. 7 ações foram afetadas pelas duas crises norteamericanas. Os resultados reforçam a importância da análise de contágio em cada empresa individual, ao invés de utilizar o índice do mercado brasileiro como um todo. / This paper tests, through the copulas methodology, the hypothesis of financial contagion between the individual Brazilian stocks and the market indices of the countries where the crises were originated. The crises analyzed are the Terror crisis in 2001, the Argentina’s crisis in 2001, the Subprime crisis in 2007 and the Sovereign Debt crisis in 2009. In addition to this, the Brazilian economic sectors are examined in order to find out which were most affected by each crisis. The tests of the Terror crisis presented evidence of SP500 contagion to 24 Brazilian stocks, affecting, mainly, sectors related to industry and energy. The Argentina’s crisis and the European Sovereign Debt crisis presented contagion’s evidence of the Merval and Athex indices for only 3 Brazilian companies. The Subprimes crisis presented evidence of SP500 contagion for 35 Brazilian companies, mostly related to the financial, energy and industrial sectors. 7 Brazilian stocks were affected by both American crises. The results reinforce the importance of contagion analysis in each individual company, rather than using the Brazilian market index.

Os mercados financeiros são de extrema relevância para as diversas economias do mundo. Sua efetividade na atração de capitais e investimentos é notória. Atualmente, o fluxo financeiro entre os diversos países é muito intenso, devido ao fenômeno da globalização. Tal situação provoca transmissão de crises financeiras entre diferentes países. Neste contexto, a avaliação de contágio financeiro torna-se um tema bastante relevante. A presente dissertação almejou verificar se houve contágio financeiro da crise americana de 2008 sobre os países do BRIC (Brasil, Rússia, Índia e China). Para tanto, foram utilizadas duas metodologias distintas. Uma delas, devido a Fermanian et al. (2002), foi empregada para estimação não paramétrica das cópulas via kernel. Assim, pode-se averiguar se houve aumento significativo nas medidas de dependência. A outra, desenvolvida por Remillard e Scaillet (2009), é um teste de comparação entre duas cópulas empíricas que investiga se houve mudança na estrutura de dependência no período de crise. Os dois procedimentos metodológicos indicaram a ocorrência de contágio da crise americana de 2008 sobre todos os países do BRIC. / Financial markets are extremely relevant to the world's diverse economies. Its effectiveness in attracting capital and investments is notorious. Currently, the financial flow between the various countries is very intense, due to the phenomenon of globalization. This situation leads to the transmission of financial crises between different countries. In this context, the evaluation of financial contagion becomes a very relevant issue. The present dissertation aimed to verify if there was financial contagion of the 2008 US crisis on the BRIC countries (Brazil, Russia, India and China). For that, two different methodologies were used. One of them, due to Fermanian et al. (2002), was used for non-parametric estimation of copula via kernel. Thus, it can be verified if there was a significant increase in the measures of dependence. The other, developed by Remillard and Scaillet (2009), is a test of comparison between two empirical copulas that investigates if there was a change in the dependency structure in the crisis period. The two methodological procedures indicated the occurrence of contagion of the American crisis of 2008 on all BRIC countries.