My understanding is the Sec 31 fee ("SEC Fee") is collected by the exchange and remitted to the SEC. It is the customer who is actually paying the fee, not the exchange. The fee is only a few pennies or each trade but was significant for dealers who have proprietary trading accounts. The dealers succeeded in getting Congress to pass legislation to lower the fees a few years ago. There is a pretty complex formula in the law that determines the fee, and it recently went down. The Sec 31 fee is certainly not going away.