http://individuals.interactivebrokers.com/en/trading/marginRequirements/margin.php?ib_entity=llc
C: To keep your positions overnight, no more than 2.00
C: But check the SMA
C: SMA has to be positive at 3:45pm ET
C: Same for simulated account
C: Check the SMA figure in the Account box
C: Has to be positive To avoid liquidation
Reg T End of Day Margin Calculations (Reg T Margin and Cash Accounts Only)
At the end of each US trading day (15:50-16:00 ET), a Special Memorandum Account (SMA) is checked to ensure that it's > =0. If it is negative, the account is subject to liquidation. In addition, no cash withdrawal will be allowed that causes SMA to go negative on a real-time basis. SMA is calculated for all securities (stocks and options) regardless of country of trading as follows: