I keep track of my trades separately using an Excel spreadsheet (because Interactive Brokers doesn't have a nice list of trades and the running cash after each, like a bank statement). I got all formulas right, and for a year since I've been doing this, my numbers matched IB's spot on. But starting from February 2010, every few days I've noticed a rounding error of 1 or 2 cents, almost always in IB's favor. In other words, if my running cash was, say, $50,123.45 according to the spreadsheet, in the daily e-mail statement, the Ending Cash would be $50,123.43, which is 2 cents less. This can't be a calculation error on my part, because no fees or commissions are 1 or 2 cents, and I doubt it's rounding error in Excel because it hasn't happened for a year, and because it's too large (2 cents for a change in running cash amounting to at most a few thousand dollars). Has anyone else been noticing their calculations not exactly matching IB's?