Quote from IV_Trader:
so if portfolio of 100k trades with annual volatility of 30 than "One day VaR with 99% of confidence " is :
(30/16 (square root of 256) * 2.33 )*100,000=4380 $ ?
Yes, that's right. This is a parametric method, which makes an assumption about the returns distribution, which is OK for linear instruments (i.e. stocks and futures), it doesn't work for non-linear instruments (i.e. options), however.