https://www.barrons.com/articles/payment-for-order-flow-sec-...
> In an Aug. 13 working paper, five finance professors analyzed 85,000 stock trades they made through five leading retail brokers. They did get significantly different pricing through different brokers for identical orders to buy or sell at the current market price.
> But their best pricing came from a broker that takes payment for order flow, namely TD Ameritrade, now a unit of Charles Schwab. Fidelity, which takes no order payments, got worse prices on the professors’ trades than did TD Ameritrade. And its prices were no better than those from the E*Trade unit of Morgan Stanley, which does take payments. Robinhood, which used revenue from order-flow payments to subsidize the industry’s first commission-free trading, delivered middle-of-the-pack pricing.