Data Science in der Finanzökonomik

Diese Gruppe konzentriert sich auf die Entwicklung und Anwendung neuartiger Data-Science-Tools im Bereich der Finanzökonomik. Ein Schwerpunkt ist die Anwendung von Data-Science-Methoden zur Gewinnung ökonomischer Indikatoren aus unstrukturierten Daten wie Text- und Bilddaten oder Web-Scraping.

Forschungscluster
Finanzresilienz und Regulierung

Ihr Kontakt

Juniorprofessor Dr. Fabian Wöbbeking
Juniorprofessor Dr. Fabian Wöbbeking
- Abteilung Finanzmärkte
Nachricht senden +49 345 7753-851 LinkedIn Profil

Referierte Publikationen

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Herding Behavior and Systemic Risk in Global Stock Markets

Iftekhar Hasan Radu Tunaru Davide Vioto

in: Journal of Empirical Finance, September 2023

Abstract

This paper provides new evidence of herding due to non- and fundamental information in global equity markets. Using quantile regressions applied to daily data for 33 countries, we investigate herding during the Eurozone crisis, China’s market crash in 2015–2016, in the aftermath of the Brexit vote and during the Covid-19 Pandemic. We find significant evidence of herding driven by non-fundamental information in case of negative tail market conditions for most countries. This study also investigates the relationship between herding and systemic risk, suggesting that herding due to fundamentals increases when systemic risk increases more than when driven by non-fundamentals. Granger causality tests and Johansen’s vector error-correction model provide solid empirical evidence of a strong interrelationship between herding and systemic risk, entailing that herding behavior may be an ex-ante aspect of systemic risk, with a more relevant role played by herding based on fundamental information in increasing systemic risk.

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Market-implied Ratings and Their Divergence from Credit Ratings

Iftekhar Hasan Winnie P. H. Poon Jianfu Shen Gaiyan Zhang

in: Journal of Financial Research, Nr. 2, 2023

Abstract

In this article, we investigate the divergence between credit ratings (CRs) and Moody's market-implied ratings (MIRs). Our evidence shows that rating gaps provide incremental information to the market regarding issuers' default risk over CRs alone in the short horizon and outperform CRs over extended horizons. The predictive ability of rating gaps is greater for more opaque and volatile issuers. Such predictability was more pronounced during the 2008 financial crisis but weakened in the post-Dodd-Frank Act period. This finding is consistent with credit rating agencies' efforts to improve their performance when facing regulatory pressure. Moreover, our analysis identifies rating-gap signals that do (do not) lead to subsequent Moody's actions to place issuers on negative outlook and watchlists. We find that negative signals from MIR gaps have a real economic impact on issuers' fundamentals such as profitability, leverage, investment, and default risk, thus supporting the recovery-efforts hypothesis.

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Correlation Scenarios and Correlation Stress Testing

Natalie Packham Fabian Wöbbeking

in: 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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Cryptocurrency Volatility Markets

Fabian Wöbbeking

in: Digital Finance, Nr. 3, 2021

Abstract

By computing a volatility index (CVX) from cryptocurrency option prices, we analyze this market’s expectation of future volatility. Our method addresses the challenging liquidity environment of this young asset class and allows us to extract stable market implied volatilities. Two alternative methods are considered to compute volatilities from granular intra-day cryptocurrency options data, which spans over the COVID-19 pandemic period. CVX data therefore capture ‘normal’ market dynamics as well as distress and recovery periods. The methods yield two cointegrated index series, where the corresponding error correction model can be used as an indicator for market implied tail-risk. Comparing our CVX to existing volatility benchmarks for traditional asset classes, such as VIX (equity) or GVX (gold), confirms that cryptocurrency volatility dynamics are often disconnected from traditional markets, yet, share common shocks.

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A Factor-model Approach for Correlation Scenarios and Correlation Stress Testing

Natalie Packham Fabian Wöbbeking

in: Journal of Banking and Finance, April 2019

Abstract

In 2012, JPMorgan accumulated a USD 6.2 billion loss on a credit derivatives portfolio, the so-called “London Whale”, partly as a consequence of de-correlations of non-perfectly correlated positions that were supposed to hedge each other. Motivated by this case, we devise a factor model for correlations that allows for scenario-based stress testing of correlations. We derive a number of analytical results related to a portfolio of homogeneous assets. Using the concept of Mahalanobis distance, we show how to identify adverse scenarios of correlation risk. In addition, we demonstrate how correlation and volatility stress tests can be combined. As an example, we apply the factor-model approach to the “London Whale” portfolio and determine the value-at-risk impact from correlation changes. Since our findings are particularly relevant for large portfolios, where even small correlation changes can have a large impact, a further application would be to stress test portfolios of central counterparties, which are of systemically relevant size.

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Arbeitspapiere

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Illusive Compliance and Elusive Risk-shifting after Macroprudential Tightening: Evidence from EU Banking

Michael Koetter Felix Noth Fabian Wöbbeking

in: IWH Discussion Papers, Nr. 4, 2025

Abstract

<p>We study whether and how EU banks comply with tighter macroprudential policy (MPP). Observing contractual details for more than one million securitized loans, we document an elusive risk-shifting response by EU banks in reaction to tighter loan-to-value (LTV) restrictions between 2009 and 2022. Our staggered difference-in-differences reveals that banks respond to these MPP measures at the portfolio level by issuing new loans after LTV shocks that are smaller, have shorter maturities, and show a higher collateral valuation while holding constant interest rates. Instead of contracting aggregate lending as intended by tighter MPP, banks increase the number and total volume of newly issued loans. Importantly, new loans finance especially properties in less liquid markets identified by a new European Real Estate Index (EREI), which we interpret as a novel, elusive form of risk-shifting.</p>

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How to Talk Down Your Stock Performance

Andreas Barth Sasan Mansouri Fabian Wöbbeking Severin Zörgiebel

in: SSRN Discussion Papers, 2020

Abstract

We process the natural language of verbal firm disclosures in order to study the use of context specific language or jargon and its impact on financial performance. We observe that, within the Q&amp;A of earnings conference calls, managers use less jargon in responses to tougher questions, and after a quarter of bad economic success. Moreover, markets interpret the lack of precise information as a bad signal: we find lower cumulative abnormal returns and a higher implied volatility following earnings calls where managers use less jargon. These results support the argument that context specific language or jargon helps to efficiently and precisely transfer information.

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