relative vola is variance of weighted log-return of historic data(251 days). man can use it to calculate VaR(99% and 95%). man can know the percentage movement (shifts) of next days (each stock), and probability. Normally Bank uses probability 99% and 95%
For example the conengy is +/- 13%*2.64 for 1 day, 26% for 4 days. shifts * sqrt(T).