High-dimensional Portfolio Selection via an \(\ell _0\)-Constrained Regression
摘要
The Markowitz mean-variance model is a foundational tool for portfolio allocation, designed to minimize risk for a given return and budget constraint. However, traditional methods like the plug-in portfolio can be unstable, especially in high-dimensional settings where the number of assets significantly exceeds the sample size. To address this, we propose a new unconstrained regression model equivalent to the Markowitz mean-variance optimization problem but with an essential constraint: the sum of portfolio weights equals 1, incorporating the