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In finance, Jensen's alpha [1] (or Jensen's Performance Index, ex-post alpha) is used to determine the abnormal return of a security or portfolio of securities over the theoretical expected return. It is a version of the standard alpha based on a theoretical performance instead of a market index .
In finance, the Treynor reward-to-volatility model (sometimes called the reward-to-volatility ratio or Treynor measure [1]), named after American economist Jack L. Treynor, [2] is a measurement of the returns earned in excess of that which could have been earned on an investment that has no risk that can be diversified (e.g., Treasury bills or a completely diversified portfolio), per unit of ...
Sharpe ratios, along with Treynor ratios and Jensen's alphas, are often used to rank the performance of portfolio or mutual fund managers. Berkshire Hathaway had a Sharpe ratio of 0.79 for the period 1976 to 2017, higher than any other stock or mutual fund with a history of more than 30 years.
In practice, short-term government securities (such as US treasury bills) are used as a risk-free asset, because they pay a fixed rate of interest and have exceptionally low default risk. The risk-free asset has zero variance in returns if held to maturity (hence is risk-free); it is also uncorrelated with any other asset (by definition, since ...
In finance the Treynor–Black model is a mathematical model for security selection published by Fischer Black and Jack Treynor in 1973. The model assumes an investor who considers that most securities are priced efficiently, but who believes they have information that can be used to predict the abnormal performance of a few of them; the model finds the optimum portfolio to hold under such ...
For example, what does it mean if one investment has a Sharpe ratio of 0.50 and another has a Sharpe ratio of −0.50? How much worse was the second portfolio than the first? These downsides apply to all risk-adjusted return measures that are ratios (e.g., Sortino ratio, Treynor ratio, upside-potential ratio, etc.).
A stock picking rule of thumb for assets with positive beta is to buy if the Treynor ratio will be above the SML and sell if it will be below (see figure above). Indeed, from the efficient market hypothesis, it follows that we cannot beat the market. Therefore, all assets should have a Treynor ratio less than or equal to that of the market.
Jack Lawrence Treynor (February 21, 1930 – May 11, 2016) was an American economist who served as the President of Treynor Capital Management in Palos Verdes Estates, California. He was a Senior Editor and Advisory Board member of the Journal of Investment Management , and was a Senior Fellow of the Institute for Quantitative Research in Finance .