Hi Yes, that has happened to me sometimes . But in a Reg T margin account. I thought that in a portfolio margin account might be different. And I thought that all Brokers had this kind of restriction. I remember I asked to @RobertMorse that question months ago. He told me that Wedbush has what they call a leverage limit (GMV/Equity). It starts at 5.56 but it can be raised to 15X. Then I understood that was the same restriction as IB, but with less leverage, but now I think I misunderstood. The restriction in IB is gross position value must not exceed Net liquidation value multiplied by 30. And @RobertMorse is talking about Equity. I don't know if it is the same for other brokers ,but in IB Equity with loan and Net liquidation value are two very differents concepts . It is easy to have a net liquidation value of 10 and an ELV of 100 , so if the restriction in Wedbush is calculated like Gross position value/Equity with Loan that would be much less restrictive than IB. It would be good to find the answer and know what happens with other brokers, because it can be a motive to change Broker. thanks.
Assuming you have less than 1m in your account, you can see the 30x rule working by opening an order entry panel for 200 Jun 14 SPX 3000/3100/3200 put butterfly @ .05. Fill in the order entry for BUY 200 @ 0.05, then click "advanced" and "check margin". The panel will clearly show the rule disallowing the order even though the cost and risk is $1000, you need 1m+ (i.e. 34m / 30) to own 200 of that butterfly today.