A measure of a portfolio's excess return per unit of risk, equal to the portfolio's rate of return minus the risk-free rate of return, divided by the portfolio's beta. This is a similar ratio to the Sharpe ratio, except that the portfolio's beta is considered the measure of risk as opposed to the variance of portfolio returns. This is useful for assessing the excess return from each unit of systematic risk, enabling investors to evaluate how structuring the portfolio to different levels of systematic risk will affect returns.