Just so nobody else gets burnt, I wanted to post what happened today. I trade actively with Tradestation Securities who clears through Bear Stearns. I frequently use my daytrading limit on SPY trades. Recently, on substantially positive trades, I have been taking 1/2 the position off and holding the rest overnight thus staying within my overnight margin requirement and providing myself with a little safety cushion. One of the consequences of holding overnight is that your daytrading margin is reduced for all the next day. Even when you close your open position, you will not have your 4X margin available to you. That I expected. What I did not expect was that I cannot really use that margin until I close out the open position. I held SPY short on Wed. close and then added to my short early Thurs., all within my stated buying power and all perfectly well accepted by TS software. Bear Stearns is claiming a 16K margin call (yikes) and will reduce my account to cash only if I don't pay. TS is fighting them and claiming nothing was done wrong. Bottom line is TS and Bear Stearns either has to get their act together or can we say hello Interactive Brokers. Don't know if this happens elsewhere but it caught me, and apparently many other TS clients by surprise. Eyecheck