Two basic solutions have been proposed to fix the well-documented incompatibility of the sample covariance matrix with Markowitz mean-variance portfolio optimization: first, restrict leverage so much that no short sales are allowed; or, second, linearly shrink the sample covariance matrix towards...

We investigate the effects of constraining leverage and shrinking covariance matrix in constructing large portfolios, both theoretically and empirically. Considering a wide variety of setups that involve conditioning or not conditioning the covariance matrix estimator on the recent past...

This paper injects factor structure into the estimation of time-varying, large-dimensional covariance matrices of stock returns. Existing factor models struggle to model the covariance matrix of residuals in the presence of time-varying conditional heteroskedasticity in large universes....

We solve the problem of optimal risk management for an investor holding an illiquid, alpha generating fund and hedging his position with a liquid futures contract. When the investor is subject to a drawdown constraint, he is forced to reduce the total risk of his portfolio after a drawdown. In...

We develop a two-period general equilibrium model of portfolio delegation with competitive, differentially skilled managers and convex compensation contracts. We show that convex incentives lead to significant equilibrium mispricing, but reduce price volatility. In particular, price...

We study survival, price impact and portfolio impact in heterogeneous economies. We show that, under the equilibrium risk-neutral measure, long-run price impact is in fact equivalent to survival, whereas longrun portfolio impact is equivalent to survival under an agent-specific, wealth-forward...

Markowitz (1952) portfolio selection requires estimates of (i) the vector of expected returns and (ii) the covariance matrix of returns. Many proposals to address the first question exist already. This paper addresses the second question. We promote a new nonlinear shrinkage estimator of the...

We provide a representation for the nonmyopic optimal portfolio of an agent consuming only at the terminal horizon when the single state variable follows a general di usion process and the market consists of one risky asset and a risk-free asset. The key term of our representation is a new...