Institutional investors usually employ mean-variance analysis to determine optimal portfolio weights. Almost immediately upon implementation, however, the portfolio's weights become sub-optimal as changes in asset prices cause the portfolio to drift away from the optimal targets. In an idealized...

That investors should diversify their portfolios is a core principle of modern finance. Yet there are some periods where diversification is undesirable. When the portfolio’s main growth engine performs well, investors prefer the opposite of diversification. An ideal complement to the growth...

Policy portfolios are a fixture of institutional investment management, but they may not serve the purposes for which they are intended. A policy portfolio serves primarily as an expression of an investor's return and risk preferences. Secondarily, it serves as a benchmark for determining the...

The authors describe a new prediction system based on the concept of statistical relevance, which defines the most useful observations for forming predictions. Their prediction system also encompasses the notion of fit, which enables one to assess the unique reliability of each individual...

The authors apply a Hidden Markov Model to identify regimes of shifting inflation and then employ an attribution technique based on the Mahalanobis distance to identify the economic variables that determine the trajectory of inflation. Their analysis enables policymakers to focus on the most...

Investors typically measure an asset’s potential to diversify a portfolio by its correlations with the portfolio’s other assets, but correlation is useful only if it provides a good estimate of how an asset’s returns co-occur cumulatively with the other asset returns over the investor’s...

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...

Financial analysts typically estimate volatilities and correlations from monthly or higher frequency returns when determining the optimal composition of a portfolio. Although it is widely acknowledged that these measures are not necessarily stationary across samples, most analysts assume...

Factor investing has gained widespread acceptance among institutional investors. Some investors believe it is preferable to stratify the investment universe into factors to manage portfolio risk more effectively, while other investors focus on factors because they believe they yield risk...

The authors describe a new statistical concept called relevance from a conceptual and mathematical perspective, and based on their mathematical framework, they present a unified theory of relevance, regressions, and event studies. They also include numerical examples of how relevance is used to...