Systemic risk in banking networks: Advantages of “tiered” banking systems

This paper studies the risk and potential impact of system-wide defaults in a tiered banking network, where a small group of head institutions has many credit linkages with other banks, while the majority of banks have only a few links. A network is random and displays a given distribution of the number of banks׳ linkages, known as degree. We model tiering by a negative correlation between degrees of neighboring banks and by a scale-free degree distribution. The main findings of the paper highlight the advantages of tiering. Both the risk of systemic crisis and the potential scope of the crisis are lower in systems with negative correlation of bank degrees than in other types of systems. Similarly, in scale-free networks, the resilience of the system to shocks is increasing with the level of tiering.     

Orthogonalized factors and systematic risk decomposition

In the context of linear multi-factor models, this study proposes an egalitarian, optimal and unique procedure to find orthogonalized factors, which also facilitates the decomposition of the coefficient of determination. Importantly, the new risk factors may diverge significantly from the original ones. The decomposition of risk allows one to explicitly examine the impact of individual factors on the return variation of risky assets, which provides discriminative power for factor selection. The procedure is experimentally robust even for small samples. Empirically we find that even though, on average, approximately eighty (sixty-five) percent of style (industry) portfolios’ volatility is explained by the market and size factors, other factors such as value, momentum and contrarian still play an important role for certain portfolios. The components of systematic risk, while dynamic over time, generally exhibit negative correlation between market, on one side, and size, value, momentum and contrarian, on the other side.     

Systemic risk governance in a dynamical model of a banking system with stochastic assets and liabilities

We consider the problem of governing systemic risk in an assets–liabilities dynamical model of a banking system. In the model considered, each bank is represented by its assets and liabilities. The net worth of a bank is the difference between its assets and liabilities and bank is solvent when its net worth is greater than or equal to zero; otherwise, the bank has failed. The banking system dynamics is defined by an initial value problem for a system of stochastic differential equations whose independent variable is time and whose dependent variables are the assets and liabilities of the banks. The banking system model presented generalizes those discussed in Fouque and Sun (in: Fouque, Langsam (eds) Handbook of systemic risk, Cambridge University Press, Cambridge, pp 444–452, 2013) and Fatone and Mariani (J Glob Optim 75(3):851–883, 2019) and describes a homogeneous population of banks. The main features of the model are a cooperation mechanism among banks and the possibility of the (direct) intervention of the monetary authority in the banking system dynamics. By “systemic risk” or “systemic event” in a bounded time interval, we mean that in that time interval at least a given fraction of banks have failed. The probability of systemic risk in a bounded time interval is evaluated via statistical simulation. Systemic risk governance aims to maintain the probability of systemic risk in a bounded time interval between two given thresholds. The monetary authority is responsible for systemic risk governance. The governance consists in the choice of assets and liabilities of a kind of “ideal bank” as functions of time and in the choice of the rules for the cooperation mechanism among banks. These rules are obtained by solving an optimal control problem for the pseudo mean field approximation of the banking system model. Governance induces banks in the system to behave like the “ideal bank”. Shocks acting on the banks’ assets or liabilities are simulated. Numerical examples of systemic risk governance in the presence and absence of shocks acting on the banking system are studied.

     

Interest rate and bank stock returns asymmetry: Evidence from U.S. banks

We use the multivariate extension of Exponential Generalized Autoregressive Conditionally Heteroscedastic (EGARCH) of Nelson, Econometrica, 59: 347–370, 1991 to test for spillover effects and examine the extent of asymmetries between short- and long-term interest rates and portfolios of money center, large, and medium-size banks in the U.S. Our results indicate the existence of price and volatility spillovers from short- and long-term interest rates to the three bank portfolios. We also provide evidence of response asymmetries for the portfolios of money center and large banks, suggesting that money center and large banks are more sensitive to negative than positive short- and long-term interest rate changes.

The dynamics of the leverage cycle

We present a simple agent-based model of a financial system composed of leveraged investors such as banks that invest in stocks and manage their risk using a Value-at-Risk constraint, based on historical observations of asset prices. The Value-at-Risk constraint implies that when perceived risk is low, leverage is high and vice versa; a phenomenon that has been dubbed pro-cyclical leverage. We show that this leads to endogenous irregular oscillations, in which gradual increases in stock prices and leverage are followed by drastic market collapses, i.e. a leverage cycle. This phenomenon is studied using simplified models that give a deeper understanding of the dynamics and the nature of the feedback loops and instabilities underlying the leverage cycle. We introduce a flexible leverage regulation policy in which it is possible to continuously tune from pro-cyclical to countercyclical leverage. When the policy is sufficiently countercyclical and bank risk is sufficiently low the endogenous oscillation disappears and prices go to a fixed point. While there is always a leverage ceiling above which the dynamics are unstable, countercyclical leverage policies can be used to raise the ceiling. We also study the impact on leverage cycles of direct, temporal control of the bank׳s riskiness via the bank׳s required Value-at-Risk quantile. Under such a rule the regulator relaxes the Value-at-Risk quantile following a negative stock price shock and tightens it following a positive shock. While such a policy rule can reduce the amplitude of leverage cycles, its effectiveness is highly dependent on the choice of parameters. Finally, we investigate fixed limits on leverage and show how they can control the leverage cycle.     

Analyst Herding and Stock Price Crash Risk: Evidence from China

We examine the proposition that firms with disproportionately more analysts herding in their coverage, as measured by a larger herding index value, have higher crash risk. Our findings are consistent with the main proposition. The results suggest that information production, rather than monitoring, is the primary mechanism behind the positive relation between herding and crash risk. Our conclusion is robust to different measures of crash risk, crash risk windows, herding measures, subsamples, and instrumental estimation. In addition, using post‐earnings announcement drift, we report that analyst herding slows down bad news transmission in the market. Our findings extend the literature by documenting that analyst herding plays a role in enhancing crash risk. Analyst herding has economic consequences on the covered firms. We offer support for the concern in the literature regarding analyst herding and market fluctuations.     

A bidimensional approach to mortality risk

Abstract We analyze the evolution over time of portfolios of life insurance contracts referring to different cohorts or risk classes of insureds. We model the intensity of mortality as a random field, in order to capture cross-generation (risk class) effects induced by the on-going management of portfolios of policies. Applications are described in the context of mortality risk analysis and (market) valuation of liabilities at aggregate level. It is shown how the model can be employed when an insurer’s new business is considered.     

Transition matrix models of consumer credit ratings

Although the corporate credit risk literature includes many studies modelling the change in the credit risk of corporate bonds over time, there has been far less analysis of the credit risk for portfolios of consumer loans. However, behavioural scores, which are calculated on a monthly basis by most consumer lenders, are the analogues of ratings in corporate credit risk. Motivated by studies of corporate credit risk, we develop a Markov chain model based on behavioural scores for establishing the credit risk of portfolios of consumer loans. Although such models have been used by lenders to develop models for the Basel Accord, nothing has been published in the literature on them. The model which we suggest differs in many respects from the corporate credit ones based on Markov chains — such as the need for a second order Markov chain, the inclusion of economic variables and the age of the loan. The model is applied using data on a credit card portfolio from a major UK bank.     

Understanding the consequences of diversification on financial stability

In this paper, we study the consequences of diversification on financial stability and social welfare using an agent based model that couples the real economy and a financial system. We validate the model against its ability to reproduce several stylized facts reported in real economies. We find that the risk of an isolated bank failure (i.e. idiosyncratic risk) is decreasing with diversification. In contrast, the probability of joint failures (i.e. systemic risk) is increasing with diversification which results in more downturns in the real sector. Additionally, we find that the system displays a “robust yet fragile” behaviour particularly for low diversification. Moreover, we study the impact of introducing preferential attachment into the lending relationships between banks and firms. Finally, we show that a regulatory policy that promotes bank–firm credit transactions that reduce similarity between banks can improve financial stability whilst permitting diversification.

     

Disorder in the Risk Order

Abstract

This paper studies the difference in global equity portfolios allocated by the criterion of minimizing the risk by using two different risk measures, the standard deviation and the conditional value at risk. An empirical analysis is performed on a comprehensive stock exchange database. The main hypothesis of the present work is that the choice of risk measure has crucial importance in portfolio optimisation, especially in those situations when the stock markets are extremely volatile and the return distributions are non-normal. The rationale behind establishing minimum-risk portfolios is to keep track of the highest possible risk reduction benefits from international diversification.     

Financial innovation and bank behavior: Evidence from credit markets

This paper investigates whether, and through which channel, the active use of credit derivatives changes bank behavior in the credit market, and how this channel was affected by the crisis of 2007–2009. Our principal finding is that banks with larger gross positions in credit derivatives charge significantly lower corporate loan spreads, while banks׳ net positions are not consistently related to loan pricing. We argue that this is consistent with banks passing on risk management benefits to corporate borrowers but not with alternative channels through which credit derivative use may affect loan pricing. We also find that the magnitude of the risk management effect remained unchanged during the crisis period of 2007–2009. In addition, banks with larger gross positions in credit derivatives cut their lending by less than other banks during the crisis and have consistently lower loan charge-offs. In sum, our study is suggestive of significant risk management benefits from financial innovations that persist under adverse conditions – that is, when they matter most.     

Does the bank risk concentration freeze the interbank system?

Probably, one test of the stability of the banking system is to evaluate how risky assets are distributed across banks’ portfolios and the implications for the contagion via interbank relations. This paper explores theoretically a bank sector with risks concentration and the functioning of interbank markets. It employs a simple model where banks are exposed to both credit and liquidity risk that suddenly correlate over the business cycle. We show that risk concentration makes interbank market breakdowns more likely and welfare monotonically decreases in risk concentration.     

Credit risk securitization and bank soundness in Europe

Using a unique sample of 749 cash and synthetic securitization transactions issued by 60 stock-listed bank holdings in the EU-13 plus Switzerland over the period from 1997 to 2007 this paper provides empirical evidence that credit risk securitization has a negative impact on the issuing banks’ financial soundness. Baseline findings hold even when controlling for likely reverse causality by employing instrumental variable techniques and substituting the accounting-based z-score ratio by market-based indicators of bank risk. Moreover, investigating the relationship between credit risk securitization and single z-score components in order to evaluate significant transmission channels proposed by relevant theoretical literature, we find a negative impact of securitization on bank profitability and capital environment as well as a positive relationship between securitization and the issuing bank's return volatility. Against the background of our empirical results we underline that the decision by the Basel Committee to enhance the new Basel III framework in the field of securitization is a step in the right direction.     

Systemic risk and bank business models

In this paper, we decompose banks' systemic risk into two dimensions: the risk of a bank (“bank tail risk”) and the link of the bank to the system in financial distress (“systemic linkage”). Based on extreme value theory, we estimate a systemic risk measure that can be decomposed into two subcomponents reflecting these dimensions. Empirically, we assess the relationships of bank business models to the two dimensions of systemic risk. The observed differences in these relationships partly explain why micro‐ and macroprudential perspectives sometimes have different implications for banking regulation.     

Is there a diversification “cost” of Shari’ah compliance? Empirical evidence from Malaysian equities

Islamic equity portfolios work with a smaller investment universe given the filtering of non-Shari’ah compliant stocks. It has been theoretically argued that this culminates in suboptimal portfolio diversification, which in turn adversely affects risk-adjusted returns. We offer empirical evidence that such a conceived portfolio diversification “penalty” is far from a foregone conclusion, at least empirically. Our results tend to indicate that Islamic portfolios are not invariably handicapped in terms of portfolio diversification. We also explored dimensions that may account for differences in the relative investment performance between Islamic and conventional portfolios, such as portfolio constraints, short selling and market conditions. We believe this paper is among the first to apply substantial empirical analysis specifically with respect to the portfolio diversification perspective on Islamic equity investments.     

基于DCC模型的上市银行系统风险实证研究

本文应用DCC多元GARCH模型分析上市银行股票价格的动态相关性,并以此作为银行整体风险的度量监测指标,在模型的构建中考虑了系统风险的时变特征。结果表明,相关系数的大小和动态变化能够对银行系统性风险起到一定的监测和预警作用。本次金融危机过后,银行间动态相关水平一直处于高位,表明投资者对未来银行资产质量和其潜在风险仍然存在担忧。     

Trading income and bank charter value during the financial crisis: Does derivatives dealer designation matter?

Derivative markets have exploded over the last decade, remained active in the midst of the 2007–2009 financial crisis and continue to be dominated by a small group of bank holding companies (BHC). BHC motives for derivative usage are usually tied to hedging purposes (balance sheet risk management), trading purposes (profit motives) or some combination thereof. This paper examines the relationship between derivative trading income and bank charter value for 27 BHC between 2001Q1 and 2011Q3. We find that the impact of derivative trading income on bank charter value, using Tobin's Q, is very small and seems to be tied to BHCs derivatives dealer trading designation. We also find that trading incomes are a modest fraction of net operating revenue, highly volatile, and did not contribute to overall BHC income during the crisis.     

Networks and market-based measures of systemic risk: the European banking system in the aftermath of the financial crisis

This article investigates the behaviour of the European banking system during the financial crises that occurred in the last decades. Among the various approaches for measuring systemic risk, we consider network analysis, which describes the linkages among financial institutions and their whole structure. We construct a time-varying network of the European banking system. Banks are linked to form a global interconnected system and they mutually influence one another in terms of risk. We model their reciprocal influence via a weighted and directed network, in which weights are related to risk measures that are based on equity returns. Then, we apply two network indicators to investigate the prominence of a bank in spreading and receiving risk from the others. The results enable us to capture many features of the banking system while identifying the global systemically important banks. Moreover, the results of the analysis over time show how interconnections change over periods that are characterized by various economic scenarios.

     

Analyzing credit risk transmission to the nonfinancial sector in Europe: A network approach

We use a factor model and elastic net shrinkage to model a high-dimensional network of European credit default swap (CDS) spreads. Our empirical approach allows us to assess the joint transmission of bank and sovereign risk to the nonfinancial corporate sector. Our findings identify a sectoral clustering in the CDS network, where financial institutions are in the center and nonfinancial entities as well as sovereigns are grouped around the financial center. The network has a geographical component reflected in different patterns of real-sector risk transmission across countries. Our framework also provides dynamic estimates of risk transmission, a useful tool for systemic risk monitoring.     

Heterogeneous beliefs with herding behaviors and asset pricing in two goods world

We construct a incomplete information equilibrium model with heterogeneous beliefs and herding behaviors to identify their joint effects on the dynamics of asset prices. Herding behaviors make investors revise some of their estimations about expected growth rates of goods streams toward to the other one’s by a manner of weighted average of their own forecast and the other’s. As we expected, herding behaviors generate influences on the Radon Nikodym derivative, that is so-called “sentiment” as in Dumas et al. (2009), and in turn not only impact the dynamics of asset prices but also generate influences on investors’ survivals. We also show that introducing heterogeneous beliefs with herding behaviors permits to explain both the Backus–Smith puzzle and the mixed results about the influences of herding behaviors on asset prices. Moreover, we uncover that herding behaviors have positive influences on stocks’ risk premiums.