Sujit Kapadia

Contagion in financial networks

This paper develops an analytical model of contagion in financial networks with arbitrary structure. We explore how the probability and potential impact of contagion is influenced by aggregate and idiosyncratic shocks, changes in network structure and asset market liquidity. Our findings suggest that financial systems exhibit a robust-yet-fragile tendency: while the probability of contagion may be low, the effects can be extremely widespread when problems occur. And we suggest why the resilience of the system in withstanding fairly large shocks prior to 2007 should not have been taken as a reliable guide to its future robustness.

Funding liquidity risk in a quantitative model of systemic stability

We demonstrate how the introduction of liability-side feedbacks affects the properties of a quantitative model of systemic risk. The model is known as RAMSI and is still in its development phase. It is based on detailed balance sheets for UK banks and encompasses macro-credit risk, interest and non-interest income risk, network interactions, and feedback effects. Funding liquidity risk is introduced by allowing for rating downgrades and incorporating a simple framework in which concerns over solvency, funding profiles and confidence may trigger the outright closure of funding markets to particular institutions. In presenting results, we focus on aggregate distributions and analysis of a scenario in which large losses at some banks can be exacerbated by liability-side feedbacks, leading to system-wide instability.

A Network Model of Financial System Resilience

We examine the role of macroeconomic fluctuations, asset market liquidity, and network structure in determining contagion and aggregate losses in a stylised financial system. Systemic instability is explored in a financial network comprising three distinct, but interconnected, sets of agents - domestic banks, overseas banks, and firms. Calibrating the model to advanced country banking sector data, this preliminary model generates broadly sensible aggregate loss distributions which are bimodal in nature. We demonstrate how systemic crises may occur and analyse how our results are influenced by fire-sale externalities and the feedback effects from curtailed lending in the macroeconomy. We also illustrate the resilience of our model financial system to stress scenarios with sharply rising corporate default rates and falling asset prices.

Size and Complexity in Model Financial Systems

The global financial crisis has precipitated an increasing appreciation of the need for a systemic perspective toward financial stability. For example: What role do large banks play in systemic risk? How should capital adequacy standards recognize this role? How is stability shaped by concentration and diversification in the financial system? We explore these questions using a deliberately simplified, dynamic model of a banking system that combines three different channels for direct transmission of contagion from one bank to another: liquidity hoarding, asset price contagion, and the propagation of defaults via counterparty credit risk. Importantly, we also introduce a mechanism for capturing how swings in “confidence” in the system may contribute to instability. Our results highlight that the importance of relatively large, well-connected banks in system stability scales more than proportionately with their size: the impact of their collapse arises not only from their connectivity, but also from their effect on confidence in the system. Imposing tougher capital requirements on larger banks than smaller ones can thus enhance the resilience of the system. Moreover, these effects are more pronounced in more concentrated systems, and continue to apply, even when allowing for potential diversification benefits that may be realized by larger banks. We discuss some tentative implications for policy, as well as conceptual analogies in ecosystem stability and in the control of infectious diseases.

Financial innovation, macroeconomic stability and systemic crises

We present a general equilibrium model of intermediation designed to capture some of the key features of the modern financial system. The model incorporates financial constraints and state-contingent contracts, and captures the spillovers associated with asset fire sales during periods of stress. If a sufficiently severe shock occurs during a credit expansion, these spillovers can potentially generate a systemic financial crisis that may be self-fulfilling. Our model suggests that financial innovation and greater macroeconomic stability may have made financial crises in developed countries less likely than in the past, but potentially more severe.

Taking Uncertainty Seriously: Simplicity versus Complexity in Financial Regulation

Distinguishing between risk and uncertainty, this paper draws on the psychological literature on heuristics to consider whether and when simpler approaches may outperform more complex methods for modelling and regulating the financial system. We find that: (i) simple methods can sometimes dominate more complex modelling approaches for calculating banks’ capital requirements, especially if limited data are available for estimating models or the underlying risks are characterised by fat-tailed distributions; (ii) simple indicators often outperformed more complex metrics in predicting individual bank failure during the global financial crisis; and (iii) when combining information from different indicators to predict bank failure, ‘fast-and-frugal’ decision trees can perform comparably to standard, but more information-intensive, regression techniques, while being simpler and easier to communicate.

Systemic risk in modern financial systems: analytics and policy design

Purpose - In recent years, the financial system has been changing rapidly. At the same time, macroeconomic volatility has fallen in developed countries. The purpose of this paper is to examine how these developments may have affected the nature of systemic crises. The paper also aims to discuss how central banks and other financial regulators might respond to these developments with a clearer, more rigorous, operational framework for their systemic financial stability work. Design/methodology/approach - The paper describes analytical models developed at the Bank of England to assess how recent developments may have affected the probability and potential impact of systemic financial crises. The results from these models help to shape the practical framework for the Banks financial stability work. Findings - The models suggest that financial innovation and integration, coupled with greater macroeconomic stability, have served to make systemic crises in developed countries less likely than in the past, but potentially more severe. Implementing a practical framework for financial stability work in response to this raises many formidable challenges. Practical implications - If individuals are risk-averse, the recent change in the profile of crises could lower welfare and would suggest that policymakers should place a higher premium on actions to monitor and mitigate systemic risk. The analysis also highlights the importance of differentiating the probability of risks from their potential impact. Originality/value - The paper will be of interest to academics interested in systemic risk, central bankers, financial regulators, and financial market participants.

Liquidity Risk, Cash-Flow Constraints and Systemic Feedbacks

The endogenous evolution of liquidity risk is a key driver of financial crises. This paper models liquidity feedbacks in a quantitative model of systemic risk. The model incorporates a number of channels important in the current financial crisis. As banks lose access to longer-term funding markets, their liabilities become increasingly short term, further undermining confidence. Stressed banks’ defensive actions include liquidity hoarding and asset fire sales. This behaviour can trigger funding problems at other banks and may ultimately cause them to fail. In presenting results, we analyse scenarios in which these channels of contagion operate, and conduct illustrative simulations to show how liquidity feedbacks may markedly amplify distress.