Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns

We studied decades-long (1980 to 2024) historic distributions of accumulated S&P500 returns, from daily returns to those over several weeks. The time series of the returns emphasize major upheavals in the markets—Black Monday, Tech Bubble, Financial Crisis, and the COVID pandemic—which are refle...

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Main Authors: Hamed Farahani, Rostislav A. Serota
Format: Article
Language:English
Published: MDPI AG 2025-06-01
Series:Economies
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Online Access:https://www.mdpi.com/2227-7099/13/6/176
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author Hamed Farahani
Rostislav A. Serota
author_facet Hamed Farahani
Rostislav A. Serota
author_sort Hamed Farahani
collection DOAJ
description We studied decades-long (1980 to 2024) historic distributions of accumulated S&P500 returns, from daily returns to those over several weeks. The time series of the returns emphasize major upheavals in the markets—Black Monday, Tech Bubble, Financial Crisis, and the COVID pandemic—which are reflected in the tail ends of the distributions. De-trending the overall gain, we concentrated on comparing distributions of gains and losses. Specifically, we compared the tails of the distributions, which are believed to exhibit a power-law behavior and possibly contain outliers. To this end, we determined confidence intervals of the linear fits of the tails of the complementary cumulative distribution functions on a log–log scale and conducted a statistical U-test in order to detect outliers. We also studied probability density functions of the full distributions of the returns with an emphasis on their asymmetry. The key empirical observations are that the mean of de-trended distributions increases near-linearly with the number of days of accumulation while the overall skew is negative—consistent with the heavier tails of losses—and depends little on the number of days of accumulation. At the same time, the variance of the distributions exhibits near-perfect linear dependence on the number of days of accumulation; that is, it remains constant if scaled to the latter. Finally, we discuss the theoretical framework for understanding accumulated returns. Our main conclusion is that the current state of theory, which predicts symmetric or near-symmetric distributions of returns, cannot explain the aggregate of empirical results.
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spelling doaj-art-c1caa7016e5b4c79983c41be848341d72025-08-20T03:27:15ZengMDPI AGEconomies2227-70992025-06-0113617610.3390/economies13060176Asymmetry in Distributions of Accumulated Gains and Losses in Stock ReturnsHamed Farahani0Rostislav A. Serota1Department of Physics, University of Cincinnati, Cincinnati, OH 45221-0011, USADepartment of Physics, University of Cincinnati, Cincinnati, OH 45221-0011, USAWe studied decades-long (1980 to 2024) historic distributions of accumulated S&P500 returns, from daily returns to those over several weeks. The time series of the returns emphasize major upheavals in the markets—Black Monday, Tech Bubble, Financial Crisis, and the COVID pandemic—which are reflected in the tail ends of the distributions. De-trending the overall gain, we concentrated on comparing distributions of gains and losses. Specifically, we compared the tails of the distributions, which are believed to exhibit a power-law behavior and possibly contain outliers. To this end, we determined confidence intervals of the linear fits of the tails of the complementary cumulative distribution functions on a log–log scale and conducted a statistical U-test in order to detect outliers. We also studied probability density functions of the full distributions of the returns with an emphasis on their asymmetry. The key empirical observations are that the mean of de-trended distributions increases near-linearly with the number of days of accumulation while the overall skew is negative—consistent with the heavier tails of losses—and depends little on the number of days of accumulation. At the same time, the variance of the distributions exhibits near-perfect linear dependence on the number of days of accumulation; that is, it remains constant if scaled to the latter. Finally, we discuss the theoretical framework for understanding accumulated returns. Our main conclusion is that the current state of theory, which predicts symmetric or near-symmetric distributions of returns, cannot explain the aggregate of empirical results.https://www.mdpi.com/2227-7099/13/6/176accumulated returnsS&P500power-law tailsoutliersskewness
spellingShingle Hamed Farahani
Rostislav A. Serota
Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns
Economies
accumulated returns
S&P500
power-law tails
outliers
skewness
title Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns
title_full Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns
title_fullStr Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns
title_full_unstemmed Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns
title_short Asymmetry in Distributions of Accumulated Gains and Losses in Stock Returns
title_sort asymmetry in distributions of accumulated gains and losses in stock returns
topic accumulated returns
S&P500
power-law tails
outliers
skewness
url https://www.mdpi.com/2227-7099/13/6/176
work_keys_str_mv AT hamedfarahani asymmetryindistributionsofaccumulatedgainsandlossesinstockreturns
AT rostislavaserota asymmetryindistributionsofaccumulatedgainsandlossesinstockreturns