Correlation Scenarios and Correlation Stress Testing
Natalie Packham, Fabian Wöbbeking
Journal of Economic Behavior and Organization,
January
2023
Abstract
We develop a general approach for stress testing correlations of financial asset portfolios. The correlation matrix of asset returns is specified in a parametric form, where correlations are represented as a function of risk factors, such as country and industry factors. A sparse factor structure linking assets and risk factors is built using Bayesian variable selection methods. Regular calibration yields a joint distribution of economically meaningful stress scenarios of the factors. As such, the method also lends itself as a reverse stress testing framework: using the Mahalanobis distance or Highest Density Regions (HDR) on the joint risk factor distribution allows to infer worst-case correlation scenarios. We give examples of stress tests on a large portfolio of European and North American stocks.
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The Disciplining Effect of Supervisory Scrutiny in the EU-wide Stress Test
Christoffer Kok, Carola Müller, Steven Ongena, Cosimo Pancaro
Journal of Financial Intermediation,
January
2023
Abstract
Relying on confidential supervisory data related to the 2016 EU-wide stress test, this paper presents novel empirical evidence that supervisory scrutiny associated to stress testing has a disciplining effect on bank risk. We find that banks that participated in the 2016 EU-wide stress test subsequently reduced their credit risk relative to banks that were not part of this exercise. Relying on new metrics for supervisory scrutiny that measure the quantity, potential impact, and duration of interactions between banks and supervisors during the stress test, we find that the disciplining effect is stronger for banks subject to more intrusive supervisory scrutiny during the exercise. We also find that a strong risk management culture is a prerequisite for the supervisory scrutiny to be effective. Finally, we show that a similar disciplining effect is not exerted neither by higher capital charges nor by more transparency and related market discipline induced by the stress test.
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The Corona Recession and Bank Stress in Germany
Reint E. Gropp, Michael Koetter, William McShane
IWH Online,
No. 4,
2020
Abstract
We conduct stress tests for a large sample of German banks across different recoveries from the Corona recession. We find that, depending on how quickly the economy recovers, between 6% to 28% of banks could become distressed from defaulting corporate borrowers alone. Many of these banks are likely to require regulatory intervention or may even fail. Even in our most optimistic scenario, bank capital ratios decline by nearly 24%. The sum of total loans held by distressed banks could plausibly range from 127 to 624 billion Euros and it may take years before the full extent of this stress is observable. Hence, the current recession could result in an acute contraction in lending to the real economy, thereby worsening the current recession , decelerating the recovery, or perhaps even causing a “double dip” recession. Additionally, we show that the corporate portfolio of savings and cooperative banks is more than five times as exposed to small firms as that of commercial banks and Landesbanken. The preliminary evidence indicates small firms are particularly exposed to the current crisis, which implies that cooperative and savings banks are at especially high risk of becoming distressed. Given that the financial difficulties may seriously impair the recovery from the Covid-19 crisis, the pressure to bail out large parts of the banking system will be strong. Recent research suggests that the long run benefits of largely resisting these pressures may be high and could result in a more efficient economy.
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Stress Tests and Small Business Lending
Kristle R. Cortés, Yuliya Demyanyk, Lei Li, Elena Loutskina, Philip E. Strahan
Journal of Financial Economics,
No. 1,
2020
Abstract
Post-crisis stress tests have altered banks’ credit supply to small business. Banks most affected by stress tests reallocate credit away from riskier markets and toward safer ones. They also raise interest rates on small loans. Quantities fall most in high-risk markets where stress-tested banks own no branches, and prices rise mainly where they do. The results suggest that banks price the stress-test induced increase in capital requirements where they have local knowledge, and exit where they do not. Stress tests do not, however, reduce aggregate credit. Small banks seem to increase their share in geographies formerly reliant on stress-tested lenders.
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