Momentum investing : does it yield excess returns to investors and why? A study of the Johannesburg Stock Exchange
Thesis (MBA)--Stellenbosch University, 2012.
The success of momentum investing has puzzled the investment society for quite some time. Numerous academics have released studies that proved the success of different momentum investing strategies, even after compensating for trading costs. According to the efficient market hypothesis investors can only realise additional returns by taking additional risks. But no real risk factors can be ascribed to momentum investing. This study investigated the success of momentum investing strategies on the Johannesburg Stock Exchange (JSE) during the period January 1997 to March 2012. Three strategies were tested, namely: return momentum, price relative to high price and the crossover ratio. These strategies were tested using different combinations of testing and holding periods and only the more liquid stocks trading on the JSE were used in the study. The study showed that the momentum investing strategies generated statically significant outperformance over the period. The momentum investing strategies were then dissected according to the three risk factors identified by the Fama and French (1992) three-factor model. None of the risk factors were able to explain the outperformance of the momentum strategies. The outperformance of the momentum strategies also showed remarkable resilience after being subjected to trading costs. The success of the three momentum investing strategies is in clear contravention of the efficient market hypothesis and adds to the growing body of evidence against the hypothesis.