 InvestHub.com's Finance Dictionary and Glossary of Investment Terms Treynor Index Definition 1.
A measure of a portfolio's excess return per unit of risk, equal to the portfolio's rate of return minus the riskfree 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.  Definition 2.
A measure of the excess return per unit of risk, where excess return is defined as the difference between the portfolio's return and the riskfree rate of return over the same evaluation period and where the unit of risk is the portfolio's beta. Named after Jack Treynor. 

