As a result, there is still no clear evidence to show whether idiosyncratic volatility
is correlated with expected stock returns as well as market volatility, especially in the case
of Thailand. The empirical research mentioned above shows relationships that reflect both
positive and negative effects. Such results may lead to confusing implications, especially
over how to construct the optimal portfolio. In addition, they do not show what exactly the
role of liquidity should be in jointly determining expected stock returns. Therefore, this
paper attempts to provide some evidence from the SET50 and stock sectors of the Stock
Exchange of Thailand (SET) which show that expected stock returns are determined by
conditional idiosyncratic volatility of individual stock as well as the conditional market volatility.
The additional robustness is whether the relationship still exists after liquidity variables
are included in the models.