Hi, basic question - when calculating return on margin for a certain month (let's assume that the account only includes short options), do you devide the monthly aggregate p/l by the average margin required for these month to get the return in %? Or do devide the p/l by the entire funds that were in the account (even if they were not necessary for margin purposes)? Also, if during the month funds were added or removed from the account, so that the return is calculated separately for each period in which the cash was different, how do you make the adjustments which are necessary to get the accurate risk parameters (such as STD, drawdown) for this month? For example, if the account value was 50k and then 20k was removed from the account, so that it is now 30k, so there was no a real drawdown or a change in the market values but the 20k decline was only due to the cash removed, how would you calculate the risk factors? I think that as the return is calculated separately for any period in which the cash was different, also risk factors (such as drawdown) should be calculated seprategly for any such period, but I am not sure. Appreciate your help, thanks.