HARA-utility investors allocate their money to a risk-free fund and to a risky fund (two fund separation). The paper shows that under weak conditions, the risky fund can be approximated by the risky fund derived from exponential utility, without material effects on the certainty equivalent of...

In the continuous time-Merton-model the instantaneous stock proportions are inversely proportional to the investor’s local relative risk aversion γ. This paper analyses the conditions under which a HARA-investor can use this 1/γ-rule to approximate her optimal portfolio in a finite time...

All HARA-utility investors with the same exponent invest in a single risky fund and the risk-free asset. In a continuous time-model stock proportions are proportional to the inverse local relative risk aversion of the investor (1/γ-rule). This paper analyses the conditions under which the...