A measure of how much of a portfolio's performance can be explained by the returns from the overall market (or a benchmark index). If a portfolio's total return precisely matched that of the overall market or benchmark, its R-squared would be 1.00. If a portfolio's return bore no relationship to the market's returns, its R-squared would be 0.

A measure of the magnitude of a portfolio's past share-price fluctuations in relation to the ups and downs of the overall market (or appropriate market index). The market (or index) is assigned a beta of 1.00, so a portfolio with a beta of 1.20 would have seen its share price rise or fall by 12% when the overall market rose or fell by 10%.

A measure of the difference between a portfolio's actual returns and its expected performance, given its level of risk as measured by beta. A positive alpha figure indicates the portfolio has performed better than its beta would predict. In contrast, a negative alpha indicates the portfolio's underperformance, given the expectations established by the portfolio's beta. In addition, a negative alpha can sometimes result from the expenses that are present in a portfolio's returns, but not in the returns of the comparison index.

A measure of the degree to which a portfolio's return varies from its previous returns or from the average of all similar portfolios. The larger the standard deviation, the greater the likelihood (and risk) that a portfolio's performance will fluctuate from the average return.

A measure of risk-adjusted return. To calculate a Sharpe ratio, a portfolio's excess returns (its return in excess of the return generated by risk-free assets such as Treasury bills) is divided by the portfolio's standard deviation. The higher the Sharpe ratio, the better the portfolio's historical risk-adjusted performance.