A Note on Stein’s Overreaction Puzzle

in Decisions in Economics and Finance (2020), 43(1), 269-276

Recently, Christoffersen et al. (2013) argue that the overreaction puzzle of Stein (1989) can be explained by a variance-dependent pricing kernel. In this note, we challenge this view. Our theoretical ... [more ▼]

Recently, Christoffersen et al. (2013) argue that the overreaction puzzle of Stein (1989) can be explained by a variance-dependent pricing kernel. In this note, we challenge this view. Our theoretical results are in line with their argument that the variance under risk-neutral measure is more persistent than the variance under physical measure due to a negative variance risk premium. But our results do not support their argument that the more persistent variance is able to qualitatively explain Stein’s findings. We show theoretically that the persistence of the volatility cannot amplify the movements of long-term variance to short-term fluctuations in variance, and, therefore, conclude that Stein’s overreaction puzzle is still unsolved. [less ▲]

The Lehman Sisters Claim

E-print/Working paper (2020)

I evaluate Christine Lagarde´s claim that more female leaders can be associated with more prudence, and less of the risky decision-making that had provoked the crisis. Indeed, the proportion of women who ... [more ▼]

I evaluate Christine Lagarde´s claim that more female leaders can be associated with more prudence, and less of the risky decision-making that had provoked the crisis. Indeed, the proportion of women who are employed in decision-making and management roles in governments, large enterprises and institutions varies substantially across European countries and is oftentimes below 30%. Research suggests that in addition to biological differences, men and women show morphological dissimilarities in specific brain regions, which explain the observed differences in behavior. As a result, female decision makers tend to be more risk averse, better suited to carefully analyze a problem, superior in multitasking and better in creating solutions that work for a group. Not surprisingly, firms with more female decision makers tend to outperform their peers in terms of productivity, profitability and stock performance while taking fewer risks. In this paper, I aim to explore the effect of female decision making on aggregate equity returns. Relying on an equilibrium asset-pricing model in an economy under jump diffusion, I decompose the moments of the returns of European stock market indices into a diffusive (systematic) risk and an (idiosyncratic) extreme event risk part. For a balanced panel of European countries, I find empirical evidence for a Lehman sisters’ effect: female decision making is an important determinant of (idiosyncratic) extreme event risk. As a result, stock markets in countries with more female decision makers are characterized by higher risk aversion, lower volatility and more positive return asymmetry, primarily driven by extreme event risk, e.g. the lower frequency of negative jumps. Results are robust to the inclusion of various controls for other country- or market-specific characteristics. [less ▲]

Retail Investors' Flight-To-Risk

E-print/Working paper (2020)

Previous research suggests that the cross-section of stock returns has substantial exposure to risks captured by higher moments in market returns. In particular, the market skewness risk premium is ... [more ▼]

Previous research suggests that the cross-section of stock returns has substantial exposure to risks captured by higher moments in market returns. In particular, the market skewness risk premium is negative, statistically and economically significant, and cannot be explained by other common risk factors or firm characteristics. This is somewhat counterintuitive when one considers the usual interpretation of e.g. option-implied skewness as an indicator of jump risk or downside risk in the stock market. I find that price pressure associated with “crowded trades” of mutual funds is partly explaining the observed negative price of market skewness risk. Given that retail investors are prone to herding, the directional trading of mutual funds is correlated, and their collective actions can generate short-term price pressure on aggregate stock prices. Short sellers systematically exploit these patterns not only in the equity lending market, but also in the options market by moving in the opposite direction. Therefore, during flight-to-risk (FTR) episodes, when equity funds experience inflows and market prices are contaminated by ‘noise’, negative shifts in market skewness are due to short selling and do not necessarily reflect market participants’ fear about increased downside risk in the stock market. Therefore, stocks with a negative past skewness exposure perform well, because they positively correlate with the ‘noise’ component. As a result, while the expected market skewness risk premium is positive, the observed one is on average negative. I find that, firstly, net exchanges of equity funds are affecting the cross-section of stock returns, leading to a significant negative market skewness risk premium. Secondly, while the volatility risk premium appears to vary over time, the skewness risk premium is found to be constant. Thirdly, in line with my hypothesis, the market skewness risk premium is only significantly negative in months when retail investors transfer their money from bond funds to equity funds. Various robustness checks confirm the validity of the results. My findings also suggest that price ‘noise’ induced by uninformed trading is not vanished at the aggregate level. [less ▲]

Model Uncertainty and Pricing Performance in Option Valuation

in The Journal of Derivatives (2020), 27(3), 31-49

The objective of this paper is to evaluate option pricing model performance at the cross sectional level. For this purpose, we propose a statistical framework, in which we in particular account for the ... [more ▼]

The objective of this paper is to evaluate option pricing model performance at the cross sectional level. For this purpose, we propose a statistical framework, in which we in particular account for the uncertainty associated with the reported pricing performance. Instead of a single figure, we determine an entire probability distribution function for the loss function that is used to measure option pricing model performance. This methodology enables us to visualize the effect of parameter uncertainty on the reported pricing performance. Using a data driven approach, we confirm previous evidence that standard volatility models with clustering and leverage effects are sufficient for the option pricing purpose. In addition, we demonstrate that there is short-term persistence but long-term heterogeneity in cross-sectional option pricing information. This finding has two important implications. First, it justifies the practitioner’s routine to refrain from time series approaches, and instead estimate option pricing models on a cross-section by cross-section basis. Second, the long term heterogeneity in option prices pinpoints the importance of measuring, comparing and testing option pricing model for each cross-section separately. To our knowledge no statistical testing framework has been applied to a single cross-section of option prices before. We propose a methodology that addresses this need. The proposed framework can be applied to a broad set of models and data. In the empirical part of the paper, we show by means of example, an application that uses a discrete time volatility model on S&P 500 index options. [less ▲]

Why is the Market Skewness-Return Relationship Negative?

Scientific Conference (2019, December 13)

The observed negative relationship between market skewness and excess return or the negative price of market skewness risk in the cross-section of stock returns is somewhat counterintuitive when we ... [more ▼]

The observed negative relationship between market skewness and excess return or the negative price of market skewness risk in the cross-section of stock returns is somewhat counterintuitive when we consider the usual interpretation of e.g. option-implied skewness as an indicator of jump risk or downside risk. One possible explanation for this inconsistency is that there are factors affecting option-implied market skewness other than jump risk in the stock market. In this paper, I find that price pressure associated with “crowded trades” of mutual funds is an important endogenous factor. Given that retail investors are prone to herding, the directional trading of mutual funds is correlated, and their collective actions can generate short-term price pressure on aggregate stock prices. Short sellers systematically exploit these patterns not only in the equity lending market, but also in the options market. In line with this economic channel, I find that firstly, the significant negative relationship between market skewness and returns becomes insignificant, once I control for price pressure. Secondly, the negative relationship is only present for the “bad” downside component of risk-neutral skewness, associated with out-of-the-money put options. For the “good” upside component of risk-neutral skewness, associated with out-of-the-money call options, the relationship is always positive. Thirdly, price pressure affects the skewness-return relationship, which can be clearly distinguished from the impact of flows on the volatility-return relationship in terms of the leverage effect. [less ▲]

THE MARKET SKEWNESS-RETURN RELATIONSHIP, Plenary Talk

Scientific Conference (2019, September 25)

WHY IS THE MARKET SKEWNESS-RETURN RELATIONSHIP NEGATIVE?

Scientific Conference (2019, July 09)

WHY IS THE MARKET SKEWNESS-RETURN RELATIONSHIP NEGATIVE?

Scientific Conference (2019, May 30)

Energy Systemic Risk

Scientific Conference (2019, April 06)

Big Moves of Mutual Funds

in Eurasian Economic Review (2019), 9(1), 1-27