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An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange

Stock market gaps occur nearly every day, yet very little is known about their influence on subsequent pricing behaviour, particularly in developing economies like South Africa. The aim of this research is to comprehensively identify and analyse the relationship between overnight price gaps and subs...

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Main Author: de Jager, Johannes
Other Authors: van Rensburg, Paul
Format: Thesis
Language:Eng
Published: Department of Finance and Tax 2024
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access_status_str Open Access
author de Jager, Johannes
author2 van Rensburg, Paul
author_browse de Jager, Johannes
van Rensburg, Paul
author_facet van Rensburg, Paul
de Jager, Johannes
author_sort de Jager, Johannes
collection Thesis
description Stock market gaps occur nearly every day, yet very little is known about their influence on subsequent pricing behaviour, particularly in developing economies like South Africa. The aim of this research is to comprehensively identify and analyse the relationship between overnight price gaps and subsequent intraday returns for publicly traded South African companies. These theoretical findings will also be applied practically, with a simulated trading strategy created and tested based on the theoretical and statistical findings. The primary method of identifying the underlying relationships at play is a collection of multiple linear and multiple logistic regression models, created using data spanning 20 years and 371 companies and split into training and testing sections to ensure accurate and bias-free results. The robust set of statistical tests and analyses performed indicates a persistent and highly significant inverse relationship that exists between large overnight gaps and subsequent intraday returns. This significant relationship was also applied to a very successful mean-reversion based trading strategy, with a sustained average annual outperformance of the JSE AllShare Index observed under even the highest transaction costs of 1.3% per trade. At the lower transaction cost level associated with CFD trading, an average annual outperformance of 166% was recorded. The theoretical and practical implications of these findings are in stark contrast to the widely accepted efficient market hypothesis and provide compelling new evidence of the exploitable nature of a relatively under researched market anomaly created by the inefficiencies associated with overnight price gaps. These results also pave the way for further analyses of gap behaviour, and collectively these findings add new and meaningful results to the body of knowledge on market anomalies.
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institution University of Cape Town (South Africa)
language Eng
last_indexed 2026-06-10T12:34:38.153Z
license_str Not specified — see source repository
provenance_str_mv Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository
publishDate 2024
publishDateRange 2024
publishDateSort 2024
publisher Department of Finance and Tax
publisherStr Department of Finance and Tax
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source_str UCTD — University of Cape Town Open Access Repository
spelling oai:open.uct.ac.za:11427/39335 An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange de Jager, Johannes van Rensburg, Paul Finance and Tax Stock market gaps occur nearly every day, yet very little is known about their influence on subsequent pricing behaviour, particularly in developing economies like South Africa. The aim of this research is to comprehensively identify and analyse the relationship between overnight price gaps and subsequent intraday returns for publicly traded South African companies. These theoretical findings will also be applied practically, with a simulated trading strategy created and tested based on the theoretical and statistical findings. The primary method of identifying the underlying relationships at play is a collection of multiple linear and multiple logistic regression models, created using data spanning 20 years and 371 companies and split into training and testing sections to ensure accurate and bias-free results. The robust set of statistical tests and analyses performed indicates a persistent and highly significant inverse relationship that exists between large overnight gaps and subsequent intraday returns. This significant relationship was also applied to a very successful mean-reversion based trading strategy, with a sustained average annual outperformance of the JSE AllShare Index observed under even the highest transaction costs of 1.3% per trade. At the lower transaction cost level associated with CFD trading, an average annual outperformance of 166% was recorded. The theoretical and practical implications of these findings are in stark contrast to the widely accepted efficient market hypothesis and provide compelling new evidence of the exploitable nature of a relatively under researched market anomaly created by the inefficiencies associated with overnight price gaps. These results also pave the way for further analyses of gap behaviour, and collectively these findings add new and meaningful results to the body of knowledge on market anomalies. 2024-04-11T12:19:31Z 2024-04-11T12:19:31Z 2023 2024-04-04T12:46:14Z Thesis / Dissertation Masters MCom http://hdl.handle.net/11427/39335 Eng application/pdf Department of Finance and Tax Faculty of Commerce
spellingShingle Finance and Tax
de Jager, Johannes
An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange
thesis_degree_str Master's
title An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange
title_full An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange
title_fullStr An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange
title_full_unstemmed An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange
title_short An Investigation into The Predictive Power of Overnight Gaps on The Johannesburg Stock Exchange
title_sort investigation into the predictive power of overnight gaps on the johannesburg stock exchange
topic Finance and Tax
url http://hdl.handle.net/11427/39335
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