A great deal of research has been done on this question, but more is needed. Let me briefly characterize some results, and some open questions. Table 1 is extracted from Levy and Markowitz. The rows of the table represent various utility functions. For example, the first row reports results for U(R) = log(1 + R) where R is the rate of return on the portfolio;
the second row reports results for U(R)R = (1 + R)0.1, etc., as indicated in the first column of the table. The second through fifth columns of the table represent various sets of historical distributions of returns on portfolios. For example, the second column represents annual returns on 149 investment companies, 1958 - 1967; the third column represents annual returns on 97 stocks, etc