The risk-return relationship in the South Africa stock market - African ...

TT21 2 L( ) L t( ) log( ) log(2) [8]2t1 t12 where the first two conditional moments should be correctly specified to ensure thatthe parameters estimation is consistent.3.2 DataAnderson and Bollerslev (1997) argue that the use of high frequency data isdesirable to uncover the risk-return relationship. This is because it allows for a bettermeasurement of risk and enables precise identification of the risk-return trade-off.This is because high frequency data produces better estimates of conditionalvolatility process. The risk-return trade-off is estimated using daily returns on 50market and industry stock price indexes of the Johannesburg stock exchange listedcompanies. These market and industry stock price indexes are weighted by marketcapitalisation, where industry stock price indexes assume the Industry ClassificationBenchmark (ICB) system.The bond exchange yields on R153 (short term government bond) and R186 (longterm government bond) are used to approximate the risk-free rate of interest. Moststudies use the three month treasury bill rate for this purpose. However, the risk freerate of return is only available in monthly frequency. All data are sourced from theSouth African Reserve Bank database and spans the period January 04, 1995 toFebruary 06, 2009. This yields 2635 data points.The data for the industry stock price indexes of aerospace and defence, personalcare and household products, tobacco, utilities, electricity, gas distribution, gas,water, and multiutilities as well as alternative exchange were not available and assuch, their risk-return relationships could not be estimated. The market and industrialgroups’ stock indexes descriptions are detailed in table A1 in the appendix and theirdescriptive statistics are shown on in table 1 below. According to the descriptivestatistics, consumer goods, food producers, equity investments as well asdevelopment and venture capital stock price indexes show high volatility during thesample period based on standard deviations.6