Recent models of the evolution of preferences have provided profound new insights into the origins of risk attitudes. In most of these models the evolutionary "objective function" is the maximization of the expected number of offspring, or alternatively, the maximization of the geometric-mean...

The Capital Asset Pricing Model (CAPM) has far-reaching practical implications for both investors and corporate managers. The model implies that the market portfolio is mean variance efficient, and thus advocates passive investment. It also provides the most widely used measure of risk, beta,...

The main problem of portfolio optimization is parameter estimation error. Various methods have been suggested to mitigate this problem, among which are shrinkage, resampling, Bayesian updating, naïve diversification, and imposing constraints on the portfolio weights. This study suggests two...

The empirical distribution of firms' market capitalizations is shown to be in excellent agreement with a very skewed lognormal distribution: the largest firms are about 1000 times larger than the median firm. Can this skewed size distribution be consistent with mean-variance portfolio...

The average after-tax real interest rate on U.S. T-bills and the average rate of return on long-term government bonds (LTGB) have been negative over the last 75 years. Is this negative rate an equilibrium phenomenon or simply an empirical fluke? We show that a negative equilibrium interest rate...

Prospect Theory (PT) and Constant Relative Risk Aversion (CRRA) have clear-cut implications for the optimal asset allocation between stocks and the risk-free asset as a function of the investment horizon. While CRRA preferences imply that the allocation should be independent of the horizon, we...

Alpha is the most popular measure for evaluating the performance of both individual assets and funds. The alpha of an asset with respect to a given benchmark portfolio measures the change in the portfolio's Sharpe ratio driven by a marginal increase in the asset's portfolio weight. Thus, alpha...

The most commonly employed decision making paradigms are expected utility, prospect theory and regret theory. We examine the simple heuristic of maximizing the probability of being ahead, which in some natural economic situations may be in contradiction to all three of the above fundamental...

Disagreement is a key factor inducing trading, which has been receiving ever-increasing attention in recent years. Most research has focused on disagreement about the expected returns. Several authors have shown that if the average belief coincides with the true expected return in the portfolio...

Asness et. al. (2018) recently resurrect the size effect, concluding that it “…should be restored as one of the central cross-sectional empirical anomalies for asset pricing theory to explain”. We suggest a theoretical explanation for the size effect, based on the observation that many...