Systematic risk as defined by Bacon(2008) is the product of beta by market risk. Be careful ! It's not the same definition as the one given by Michael Jensen. Market risk is the standard deviation of the benchmark. The systematic risk is annualized
SystematicRisk(Ra, Rb, Rf = 0, scale = NA, ...)$$\sigma_s = \beta * \sigma_m$$
where \(\sigma_s\) is the systematic risk, \(\beta\) is the regression beta, and \(\sigma_m\) is the market risk
Carl Bacon, Practical portfolio performance measurement and attribution, second edition 2008 p.75
data(portfolio_bacon)
print(SystematicRisk(portfolio_bacon[,1], portfolio_bacon[,2])) #expected 0.013
#> [1] 0.132806
data(managers)
print(SystematicRisk(managers['2002',1], managers['2002',8]))
#> [1] 0.1103665
print(SystematicRisk(managers['2002',1:5], managers['2002',8]))
#> HAM1 HAM2 HAM3 HAM4
#> Systematic Risk to SP500 TR (Rf = 0) 0.1103665 0.02041913 0.08939036 0.1651298
#> HAM5
#> Systematic Risk to SP500 TR (Rf = 0) 0.02013523