Detecting and Analysing Possible Outliers in Global Stock Market Returns

We employ a Boxplot method for detecting and analyzing outlying daily returns of 14 international stock market indices sampled from around the world. The main objective of the paper is to provide an extensive analysis of the main characteristics, features and effects of the detected outlier returns....

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Main Authors: Ali A. Shehadeh, Sadam M. Alwadi, Mohammad I. Almaharmeh
Format: Article
Language:English
Published: Taylor & Francis Group 2022-12-01
Series:Cogent Economics & Finance
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Online Access:https://www.tandfonline.com/doi/10.1080/23322039.2022.2066762
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author Ali A. Shehadeh
Sadam M. Alwadi
Mohammad I. Almaharmeh
author_facet Ali A. Shehadeh
Sadam M. Alwadi
Mohammad I. Almaharmeh
author_sort Ali A. Shehadeh
collection DOAJ
description We employ a Boxplot method for detecting and analyzing outlying daily returns of 14 international stock market indices sampled from around the world. The main objective of the paper is to provide an extensive analysis of the main characteristics, features and effects of the detected outlier returns. The results show that from about 4–10% of observations constitute outlying returns with an average of 6%. Conservatively, about 1.4% of return series are extreme outliers. Negative outliers are found more frequent, influential, severe and transmissible. The bulk of detected outliers are found to be in the magnitude of three standard deviations. Also, outliers tend to cluster together, both within individual return series over time and across stock markets. We find a sequential pattern in outlier occurrence within individual return series, and a concurrent pattern across stock markets. Moreover, adjusting for outlying returns leads to a decrease in standard deviation, negative skewness and kurtosis by about 18%, 74% and 69% on average, respectively. We do not find consistent evidence that advanced and well-developed stock markets have less frequent and/or sever outliers. Overall, the results and analysis of the paper provide important considerations about international stock market returns which are relevant to stock investment, portfolio and risk management. The results show that the best (worst) outlying returns which represent about only 1% of the return observations have an enormous effect on the stock return performance and realization.
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spelling doaj-art-4f60cdbc323c41a6a64197e5011da3de2025-08-20T03:12:56ZengTaylor & Francis GroupCogent Economics & Finance2332-20392022-12-0110110.1080/23322039.2022.2066762Detecting and Analysing Possible Outliers in Global Stock Market ReturnsAli A. Shehadeh0Sadam M. Alwadi1Mohammad I. Almaharmeh2Department of Finance, The University of Jordan/Aqaba, Aqaba, JordanDepartment of Finance, The University of Jordan/Aqaba, Aqaba, JordanDepartment of Accounting , The University of Jordan/Aqaba, Aqaba, JordanWe employ a Boxplot method for detecting and analyzing outlying daily returns of 14 international stock market indices sampled from around the world. The main objective of the paper is to provide an extensive analysis of the main characteristics, features and effects of the detected outlier returns. The results show that from about 4–10% of observations constitute outlying returns with an average of 6%. Conservatively, about 1.4% of return series are extreme outliers. Negative outliers are found more frequent, influential, severe and transmissible. The bulk of detected outliers are found to be in the magnitude of three standard deviations. Also, outliers tend to cluster together, both within individual return series over time and across stock markets. We find a sequential pattern in outlier occurrence within individual return series, and a concurrent pattern across stock markets. Moreover, adjusting for outlying returns leads to a decrease in standard deviation, negative skewness and kurtosis by about 18%, 74% and 69% on average, respectively. We do not find consistent evidence that advanced and well-developed stock markets have less frequent and/or sever outliers. Overall, the results and analysis of the paper provide important considerations about international stock market returns which are relevant to stock investment, portfolio and risk management. The results show that the best (worst) outlying returns which represent about only 1% of the return observations have an enormous effect on the stock return performance and realization.https://www.tandfonline.com/doi/10.1080/23322039.2022.2066762Outliersoutliers in stock returnsBoxplotstock investmentinternational stock marketsdaily stock market returns
spellingShingle Ali A. Shehadeh
Sadam M. Alwadi
Mohammad I. Almaharmeh
Detecting and Analysing Possible Outliers in Global Stock Market Returns
Cogent Economics & Finance
Outliers
outliers in stock returns
Boxplot
stock investment
international stock markets
daily stock market returns
title Detecting and Analysing Possible Outliers in Global Stock Market Returns
title_full Detecting and Analysing Possible Outliers in Global Stock Market Returns
title_fullStr Detecting and Analysing Possible Outliers in Global Stock Market Returns
title_full_unstemmed Detecting and Analysing Possible Outliers in Global Stock Market Returns
title_short Detecting and Analysing Possible Outliers in Global Stock Market Returns
title_sort detecting and analysing possible outliers in global stock market returns
topic Outliers
outliers in stock returns
Boxplot
stock investment
international stock markets
daily stock market returns
url https://www.tandfonline.com/doi/10.1080/23322039.2022.2066762
work_keys_str_mv AT aliashehadeh detectingandanalysingpossibleoutliersinglobalstockmarketreturns
AT sadammalwadi detectingandanalysingpossibleoutliersinglobalstockmarketreturns
AT mohammadialmaharmeh detectingandanalysingpossibleoutliersinglobalstockmarketreturns