Looking at the big picture, there is nothing wrong with the practice. Revenue from PFOF goes toward paying for all the benefits you take for granted as a customer, including free streaming real-time quotes, advanced mobile apps, high-quality customer support, research reports, etc. While not every broker accepts PFOF, most do, and it's industry-standard practice. When you went to buy those 100 shares of Apple, your online broker’s routing system tried to get you the best possible price. Depending on where the order is routed, your online broker can earn a very tiny sum of money on your trade, say $0.10 - $0.20 in the case of your 100-share market order. Some brokers keep PFOF for themselves; others keep a portion of it and pass the rest back to you; and a select few pass all the earnings back to you. You won’t see it as a cash deposit; instead, you will see that your order was executed at an ever so slightly better price (price improvement). $0.10 - $0.20 may not sound like much; however, if your 100-share market order had been a 1,000-share order instead, that payment could have been $1 – $2, or more. The largest online brokers route hundreds of thousands of client trades every day. Known as daily average revenue trades (DARTs), your online broker can make millions of dollars from routing clients’ orders over the course of each year.