where rF is the Risk-free rate and is equivalent to the 10-year U.S. Treasury bond rate. Beta (βE) is the firm’s systematic risk and is measured as the covariance of the market's return with the individual company's common stock return divided by the market’s variance.Annual beta was obtained from the CRSP database. rM is the return on the market portfolio. The risk premium was based on the Fama and French [79] estimate of average returns over the period 1872 to 2000.