We investigate the properties of mean-variance efficient portfolios when the number of assets is large. We show analytically and empirically that the proportion of assets held short converges to 50% as the number of assets grows, and the investment proportions are extreme, with several assets...

Modigliani and Miller's Proposition III asserts that if a firm's projects are all similar, they should all be discounted at the same marginal cost of capital (MCC), which is also the firm's average cost of capital (ACC). However, when a firm expands by accepting a new project, its weight in...

The continuous-time CAPM assumes that investors are risk-averse. However, these is a very large body of empirical and experimental evidence documenting that many investors are not globally risk-averse: Prospect Theory and aspiration-level models are two well-known examples of this literature....