I am trying to verify the correctness of the unbundled commissions I have been charged by IB, and I am having trouble doing so. Can somebody tell me what is wrong? I sold, for example, 200 shares of SPY, at a price of 126.39, on INET, and I was offering liquidity. I calculate that my basic commission should have been 70 cents, plus about 80 cents for the SEC fees, and minus a 40 cents rebate for offering liquidity on an ETF. This comes to a total of $1.10. BUT I was actually charged $1.45. Where am I going wrong? Could it be that I did not receive the rebate? Are my calculations incorrect?