According to the Arca website, I should get charged .003 for taking liquidity and be rebated .002 for adding liquidity. However, I found that on IB's site, they charge .001 for taking liquidity from Arca on the NYSE and rebate nothing. As I dug through my clearing house statements, I found that I, too, get charged only .001 for removing liquidity from Arca on the NYSE. Bats I pay .0026, Instinet charges me .003... yet I"m somehow able to able to pay less than other traders I know for using Arca. I'm confused about how this fee structure works... does Arca charge some people .003 and others .001? If so, how are they able to rebate whoever's adding the liquidity on the otherside of my trade without losing money?