Conclusion
This study provided a joint test of a number of hypotheses on factors affecting
asset returns. By the standard CAPM, expected return should be an increasing
function of the systematic (0) risk, and Amihud and Mendelson [2] suggested
that return is increasing in the bid-ask spread which measures asset illiquidity.
Merton [26] proposed that the expected return is increasing in the asset's systematic risk (/3), residual risk, and market value and is decreasing in the
number of investors who have access to information about it and invest in it. So
far, only subsets of these hypotheses were tested. Given the documented correlations
between the above variables, a joint test is called for. Our results support
the hypotheses that expected return is an increasing function of /3 and of the bidask
spread but provide no support to the hypotheses on the effects of residual
risk and firm size.