Sharpe ratio

The Sharpe ratio gives the expected excess return of an investment over a benchmark, divided by the volatility of that excess return. It is used to compare how much reward an investment earns for each unit of risk taken.

S_a = \frac{E[R_a - R_b]}{\sigma_a} = \frac{E[R_a - R_b]}{\sqrt{\mathrm{var}[R_a - R_b]}}

What the symbols mean

Sharpe ratio of investment a (dimensionless)
return of investment a
return of the benchmark or risk-free asset
expected value of the excess return of a over b
standard deviation of the excess return, i.e. its volatility
variance of the excess return

About this formula

  • FieldEconomics and finance
  • TopicPortfolio performance measurement
  • LevelUniversity
  • Also calledSharpe index, reward-to-variability ratio, Sharpe measure, excess return per unit of risk, risk premium to volatility ratio
  • SourceWikidata Q1501898

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