Investors have traditionally relied on mean-variance analysis to determine a portfolio’s optimal asset mix, but they have struggled to incorporate private equity into this framework because they do not know how to estimate its risk. The observed volatility of private equity returns is...

We use a proprietary database of private equity returns to measure the excess return of private equity over public equity and to partition it into two components: an asset class alpha and compensation for illiquidity. Our evidence suggests that private equity managers, as a group, generate alpha...