I am considering openning an account with a deep discount online broker to save commission costs. I was told that many online brokers sell their orders to market making firms through a process called "payment-for-order-flow" Does anyone have a list of online brokers who partake in this practice? For example, if I open an account with IB to take advantage of the penny per share commission, will I be paying up in price for the stock because of payment-for-order-flow? It's seems that this should be something that brokers disclose when they offer these low commissions.