A Study on the Existence of a Low Idiosyncratic Volatility Premium on the Cross-section of Share Returns on the JSE

Abstract

As one of the renowned anomalies in modern investment theory, the low idiosyncratic volatility anomaly may be the most bewildering and captivating of them all. The anomaly defies the traditional asset pricing theories of modern portfolio theory, which state the fundamental principle that high-risk portfolios are compensated for with higher expected returns. This study determined if the low idiosyncratic volatility premium is present on the cross-section of share returns of the JSE. 12-, 36- and 60-month volatility estimation periods were used in this study to determine if this has any significant effect on share returns. A relevant 26-year sample period from January 1994 to December 2019 was employed. In examining the CAPM OLS regression results utilising the 60-month idiosyncratic volatility estimation period, statistically significant evidence was found to support the alternative hypothesis of a low idiosyncratic volatility anomaly on the cross-sectional returns on the JSE. These findings are supported by a statistically significant alpha for five of the six portfolios examined and clearly indicate the superior performance of the low volatility portfolio in contrast to the high idiosyncratic volatility portfolios. These findings of the 60-month CAPM regression analysis provide clear evidence of a low idiosyncratic volatility anomaly and reject the null hypothesis that there is no statistically significant evidence in favour of a low idiosyncratic volatility anomaly on the cross-section of share returns on the JSE after estimating volatility utilising a 60-month volatility estimation period.

As een van die bekendste anomalieë in moderne beleggingsteorie, is die lae idiosinkratiese gestadigheidsanomalie moontlik die mees verbysterende en boeiende anomalie van almal. Hierdie besondere anomalie bied ʼn uitdaging aan die tradisionele bateprysingsteorie van moderne portefeuljeteorie, die grondbeginsel waarvolgens daar vir hoërisiko-portefeuljes vergoed word deur hoër verwagte opbrengste. Die doel van hierdie studie is om te bepaal of die lae idiosinkratiese gestadigheidspremie aanwesig is by die deursnee-aandeleopbrengste op die JSE. In hierdie studie, is gestadigheidsramingstydperke van 12, 36 en 60 maande gebruik om te bepaal of dit enige beduidende uitwerking op aandeleopbrengste het. ʼn Relevante steekproeftydperk van 26 jaar van Januarie 1994 tot Desember 2019 is gebruik. Deur ondersoek van regressieresultate van die kapitaalbateprysingsmodel (KBPM) kleinste-kwadratemetode aan die hand van ʼn idiosinkratiese gestadigheidsramingstydperk van 60 maande is statisties-beduidende bewyse gevind om die alternatiewe hipotese van ʼn lae idiosinkratiese gestadigheidsanomalie in die deursnee-opbrengste op die JSE te ondersteun. Hierdie bevindings word ondersteun deur ʼn statisties-beduidende alfa vir vyf van die ses portefeuljes wat ondersoek is en dit dui duidelik op die superieure prestasie van die laegestadigheidsportefeulje in kontras met die hoë idiosinkratiese gestadigheidsportefeuljes. Die bevindings van die KBPM-regressie-analise van 60 maande voorsien duidelike bewyse van ʼn lae idiosinkratiese gestadigheidsanomalie en verwerp die nulhipotese dat daar nie statisties-beduidende bewyse is ten gunste van ʼn lae idiosinkratiese gestadigheidsanomalie in die deursnee-aandeleopbrengste op die JSE nie nadat gestadigheid geraam is aan die hand van ʼn gestadigheidsramingstydperk van 60 maande.

E le e nngwe ya diphoso tse tummeng kgopolong ya sejwale-jwale ya matsete, bothata bo tlase ba ho hloka botsitso e ka ba ntho e makatsang le e hohelang ka ho fetisisa. Phoso e ikgethileng ha e latele dikgopolo tsa ditheko tsa thekiso ya thepa ya sejwale-jwale, e hlalosang molao-theo wa hore dipotefoliyo tse kotsing e kgolo di lefellwa bakeng sa dikgutliso tse phahameng tse lebelletsweng. Phuputso ena e ne e ikemiseditse ho fumana hore na tefo e tlase ya botsitso e teng dikarolong tse sa tshwaneng tsa dikgutliso tsa dikabelo ho JSE. Phuputsong ena ho sebedisitswe dinako tsa tekanyetso ya ho hloka botsitso ya dikgwedi tse 12, 36 le tse 60 ho fumana hore na sena se na le phello e kgolo ho dikgutliso tsa dikabelo. Nako ya sampole e loketseng ya dilemo tse 26 ho tloha ka Pherekgong 1994 ho isa ho Tshitwe 2019 e ile ya sebediswa. Ha ho hlahlojwa sephetho sa tekanyo ya CAPM OLS ho sebediswa nako ya dikgakanyo tsa ho hloka botsitso ha dikgwedi tse 60, ho fumanwe bopaki ba bohlokwa ho tshehetsa mohopolo o mong wa phokotso dikgutlisong tsa dikarolo tse fapaneng ho JSE. Diphumano tsena di tsheheditswe ke qaleho ya dipalo bakeng sa dipotefoliyo tse hlano ho tse tsheletseng tse hlahlobilweng mme di bontsha tshebetso e phahameng ya potefolio e tlase ya ho hloka botsitso ho fapana le dipotefoliyo tse phahameng tsa ho hloka botsitso. Diphumano tsena tsa tlhahlobo ya tekanyo ya CAPM ya dikgwedi tse 60 di fana ka bopaki bo hlakileng ba phokotso e sa tlwaelehang ya ho hloka botsitso le ho hanyetsa kgopolo-taba ya hore ha ho na bopaki ba dipalo-palo bo tshehetsang boemo bo tlase ba ho hloka botsitso bo sa tlwaelehang dikarolong tse sa tshwaneng tsa dikabelo ho JSE kamora ho lekanyetsa ho hloka botsitso ho sebedisang nako ya dikgakanyo tsa ho hloka botsitso ya dikgwedi tse 60.