E-mini SP Overnight Initial is $5625, Overnight Maintenance is $4500. It seems to me that IB will liquidate your single ES postion if your account balance drops below $4500. While other brokers won't liquidate your position until your account balance drops to few hundred bucks.
What do you care? You closed your IB account and swore you would never go back? http://www.elitetrader.com/vb/showthread.php?s=&threadid=120339
Never heard of any broker willing to allow equity to shrink to that amount. You got an example? Of course, if all this happened during the RTH, they might leave you alone until the day trade margin was violated. But the minute you went overnight again, you'd be liquidated if your equity was a few hundred (in the case of other firms). OldTrader
IB doesn't issue margin calls they just liquidate contracts until you meet the initial margin requirement on the remaining contracts. What brokers let another $4000 a contract (80 ES points) evaporate before they liquidate the position? You should be very grateful to IB for liquidating you at the $4500 maintenance margin and saving you from losing another $4000 a contract. You are responsible for controlling your losses. If you keep violating maintenance margin you are doing something very wrong in your trading. You are always free to lose your money with any of the multitude of futures brokers other than IB. There are a number of futures brokers that have both easier margin policies and lower commissions than IB.
Don't confuse overnight margin requirements with day-trading margin. All retail brokers must use the futures exchange's established minimum for overnight margin and IB almost always follows them and does not add any extra. The exchanges have no day-trade minimums. Retail futures firms can establish any day-trade margin they like such as the $500 you mention. IB has higher minimums, typically one-half the exchange established initial overnight margin, and generally increases them when market volatility gets unusually high. Jack