Downside risk-neutral probabilities

We show that there exists a probability measure under which the CAPM formula for expected returns holds for general utility functions and probability distributions. This probability measure, the “downside risk-neutral” measure, is adjusted to incorporate the effects of downside risk and higher degree risks. It thus belongs to the same family as the risk-neutral measure, which is also a risk-adjusted measure. Using risk preference theory, we interpret this change in probability measure in terms of risk substitution.