Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion

In this article, we propose a test of the dynamics of stock market indexes typical of the US and EU capital markets in order to determine which of the two fundamental hypotheses, efficient market hypothesis (EMH) or fractal market hypothesis (FMH), best describes market behavior. The article’s major...

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Autores principales: Vasile Brătian, Ana-Maria Acu, Camelia Oprean-Stan, Emil Dinga, Gabriela-Mariana Ionescu
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Publicado: MDPI AG 2021
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spelling oai:doaj.org-article:ad6e754a33394e229605d0b22c9695ca2021-11-25T18:17:47ZEfficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion10.3390/math92229832227-7390https://doaj.org/article/ad6e754a33394e229605d0b22c9695ca2021-11-01T00:00:00Zhttps://www.mdpi.com/2227-7390/9/22/2983https://doaj.org/toc/2227-7390In this article, we propose a test of the dynamics of stock market indexes typical of the US and EU capital markets in order to determine which of the two fundamental hypotheses, efficient market hypothesis (EMH) or fractal market hypothesis (FMH), best describes market behavior. The article’s major goal is to show how to appropriately model return distributions for financial market indexes, specifically which geometric Brownian motion (GBM) and geometric fractional Brownian motion (GFBM) dynamic equations best define the evolution of the S&P 500 and Stoxx Europe 600 stock indexes. Daily stock index data were acquired from the Thomson Reuters Eikon database during a ten-year period, from January 2011 to December 2020. The main contribution of this work is determining whether these markets are efficient (as defined by the EMH), in which case the appropriate stock indexes dynamic equation is the GBM, or fractal (as described by the FMH), in which case the appropriate stock indexes dynamic equation is the GFBM. In this paper, we consider two methods for calculating the Hurst exponent: the rescaled range method (RS) and the periodogram method (PE). To determine which of the dynamics (GBM, GFBM) is more appropriate, we employed the mean absolute percentage error (MAPE) method. The simulation results demonstrate that the GFBM is better suited for forecasting stock market indexes than the GBM when the analyzed markets display fractality. However, while these findings cannot be generalized, they are verisimilar.Vasile BrătianAna-Maria AcuCamelia Oprean-StanEmil DingaGabriela-Mariana IonescuMDPI AGarticlegeometric Brownian motiongeometric fractional Brownian motionefficient market hypothesisfractal market hypothesisMathematicsQA1-939ENMathematics, Vol 9, Iss 2983, p 2983 (2021)
institution DOAJ
collection DOAJ
language EN
topic geometric Brownian motion
geometric fractional Brownian motion
efficient market hypothesis
fractal market hypothesis
Mathematics
QA1-939
spellingShingle geometric Brownian motion
geometric fractional Brownian motion
efficient market hypothesis
fractal market hypothesis
Mathematics
QA1-939
Vasile Brătian
Ana-Maria Acu
Camelia Oprean-Stan
Emil Dinga
Gabriela-Mariana Ionescu
Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion
description In this article, we propose a test of the dynamics of stock market indexes typical of the US and EU capital markets in order to determine which of the two fundamental hypotheses, efficient market hypothesis (EMH) or fractal market hypothesis (FMH), best describes market behavior. The article’s major goal is to show how to appropriately model return distributions for financial market indexes, specifically which geometric Brownian motion (GBM) and geometric fractional Brownian motion (GFBM) dynamic equations best define the evolution of the S&P 500 and Stoxx Europe 600 stock indexes. Daily stock index data were acquired from the Thomson Reuters Eikon database during a ten-year period, from January 2011 to December 2020. The main contribution of this work is determining whether these markets are efficient (as defined by the EMH), in which case the appropriate stock indexes dynamic equation is the GBM, or fractal (as described by the FMH), in which case the appropriate stock indexes dynamic equation is the GFBM. In this paper, we consider two methods for calculating the Hurst exponent: the rescaled range method (RS) and the periodogram method (PE). To determine which of the dynamics (GBM, GFBM) is more appropriate, we employed the mean absolute percentage error (MAPE) method. The simulation results demonstrate that the GFBM is better suited for forecasting stock market indexes than the GBM when the analyzed markets display fractality. However, while these findings cannot be generalized, they are verisimilar.
format article
author Vasile Brătian
Ana-Maria Acu
Camelia Oprean-Stan
Emil Dinga
Gabriela-Mariana Ionescu
author_facet Vasile Brătian
Ana-Maria Acu
Camelia Oprean-Stan
Emil Dinga
Gabriela-Mariana Ionescu
author_sort Vasile Brătian
title Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion
title_short Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion
title_full Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion
title_fullStr Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion
title_full_unstemmed Efficient or Fractal Market Hypothesis? A Stock Indexes Modelling Using Geometric Brownian Motion and Geometric Fractional Brownian Motion
title_sort efficient or fractal market hypothesis? a stock indexes modelling using geometric brownian motion and geometric fractional brownian motion
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/ad6e754a33394e229605d0b22c9695ca
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