An Empirical Re-Examination of the Weak Form Efficient Markets Hypothesis of the Ghana Stock Market Using Variance-Ratios Tests

African Finance Journal, Vol. 9, No. 2, pp.1-25, 2007

32 Pages Posted: 16 Aug 2007 Last revised: 19 Aug 2008

See all articles by Collins G. Ntim

Collins G. Ntim

University of Southampton Business School, UK; University of Southampton

Kwaku K. Opong

University of Glasgow - Adam Smith Business School

Jo Danbolt

University of Edinburgh Business School

Abstract

This study empirically re-examines the weak form efficient markets hypothesis of the Ghana Stock Market using a new robust non-parametric variance-ratios test in addition to its parametric alternative. The main finding is that stock returns are conclusively not efficient in the weak form, neither from the perspective of the strict random walk nor in the relaxed martingale difference sequence sense. Unlike previous evidence, our finding is robust to thin-trading, sub-sample periods as well as the choice of dataset. Consistent with prior studies, the results of the parametric variance-ratios test are ambiguous. By contrast, its non-parametric alternative provides conclusive results.

Keywords: Weak form efficiency, Random walk, Martingale difference sequence, Parametric and non-parametric variance-ratios tests, Ghana stock market

Suggested Citation

Ntim, Collins G. and Opong, Kwaku K. and Danbolt, Jo, An Empirical Re-Examination of the Weak Form Efficient Markets Hypothesis of the Ghana Stock Market Using Variance-Ratios Tests. African Finance Journal, Vol. 9, No. 2, pp.1-25, 2007, Available at SSRN: https://ssrn.com/abstract=1007338

Collins G. Ntim (Contact Author)

University of Southampton Business School, UK ( email )

Southampton Business School
Highfield
Southampton, England SO17 IBJ
United Kingdom
+44 (0) 238059 4285 (Phone)
+44 (0) 238059 3844 (Fax)

HOME PAGE: http://www.southampton.ac.uk/business-school/about/staff/cgn1n11.page

University of Southampton ( email )

Southampton, SO17 1BJ
United Kingdom

Kwaku K. Opong

University of Glasgow - Adam Smith Business School ( email )

University Avenue
Gilbert Scott Building
Glasgow, Scotland G12 8QQ
United Kingdom

Jo Danbolt

University of Edinburgh Business School ( email )

University of Edinburgh
29 Buccleuch Place
Edinburgh, Scotland EH8 9JS
UNITED KINGDOM

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