The Omega-Sharpe ratio is a conversion of the omega ratio to a ranking statistic in familiar form to the Sharpe ratio.
OmegaSharpeRatio(R, MAR = 0, ...)To calculate the Omega-Sharpe ration we subtract the target (or Minimum Acceptable Returns (MAR)) return from the portfolio return and we divide it by the opposite of the Downside Deviation.
$$OmegaSharpeRatio(R,MAR) = \frac{r_p - r_t}{\sum^n_{t=1}\frac{max(r_t - r_i, 0)}{n}}$$
where \(n\) is the number of observations of the entire series
Carl Bacon, Practical portfolio performance measurement and attribution, second edition 2008, p.95
data(portfolio_bacon)
MAR = 0.005
print(OmegaSharpeRatio(portfolio_bacon[,1], MAR)) #expected 0.29
#> [,1]
#> [1,] 0.2917933
MAR = 0
data(managers)
print(OmegaSharpeRatio(managers['1996'], MAR))
#> HAM1 HAM2 HAM3 HAM4 HAM5 HAM6
#> OmegaSharpeRatio (MAR = 0%) 3.598338 2374 5.482813 2.615074 NA NA
#> EDHEC LS EQ SP500 TR US 10Y TR US 3m TR
#> OmegaSharpeRatio (MAR = 0%) NA 3.340625 0.02827709 Inf
print(OmegaSharpeRatio(managers['1996',1], MAR)) #expected 3.60
#> [,1]
#> [1,] 3.598338