Net selectivity is the remaining selectivity after deducting the amount of return require to justify not being fully diversified
NetSelectivity(Ra, Rb, Rf = 0, ...)
Ra | an xts, vector, matrix, data frame, timeSeries or zoo object of asset returns |
---|---|
Rb | return vector of the benchmark asset |
Rf | risk free rate, in same period as your returns |
… | any other passthru parameters |
If net selectivity is negative the portfolio manager has not justified the loss of diversification $$Net selectivity = \alpha - d$$
where \(\alpha\) is the selectivity and \(d\) is the diversification
Carl Bacon, Practical portfolio performance measurement and attribution, second edition 2008 p.78
data(portfolio_bacon) print(NetSelectivity(portfolio_bacon[,1], portfolio_bacon[,2])) #expected -0.017#> portfolio.monthly.return.... #> portfolio.monthly.return.... -0.0178912data(managers) print(NetSelectivity(managers['1996',1], managers['1996',8]))#> HAM1 #> HAM1 0.01333906print(NetSelectivity(managers['1996',1:5], managers['1996',8]))#> HAM1 HAM2 HAM3 HAM4 HAM5 #> Net Selectivity (Risk free = 0) 0.01333906 NA 0.1745397 -0.03249043 NA