Around the start of this year, I saw a change in IB margining system, order margin seems to be processing cumulatively and not on an individual order basis, limit orders are treated no different than market orders - fills are considered certain. Previously when executing any system with pre-market limit orders, the margin algo checked individually whether I had enough for the particular order being processed, if it was a limit order, it wasn't subtracted from the excess liquidity when processing the following order. New behavior is that all orders are assumed to execute, no matter how far out the limit is. This means any type of "dip buyer" system that enters a large number of orders (low fill rate) is impossible to trade. I spoke with IB about this and according to them, there's no change in behavior. But I know for a fact I often entered orders 10x-20x above the excess liq. previously without rejections. Since most didn't execute, it wasn't a problem. The times I did violate margin, I handled the positions myself or the auto-liquidator did its job. I'm looking for information on who else experienced this, whether my account has some flags modified unbeknownst to me or was this a general change in their system. Right now it feels like boxing with my hands tied, it's a very hostile move against active traders.