  We investigate entropy as a financial risk measure. Entropy explains the
equity premium of securities and portfolios in a simpler way and, at the same
time, with higher explanatory power than the beta parameter of the capital
asset pricing model. For asset pricing we define the continuous entropy as an
alternative measure of risk. Our results show that entropy decreases in the
function of the number of securities involved in a portfolio in a similar way
to the standard deviation, and that efficient portfolios are situated on a
hyperbola in the expected return - entropy system. For empirical investigation
we use daily returns of 150 randomly selected securities for a period of 27
years. Our regression results show that entropy has a higher explanatory power
for the expected return than the capital asset pricing model beta. Furthermore
we show the time varying behaviour of the beta along with entropy.
