Robinhood Gets Almost Half Its Revenue in Bargain with High-Speed Traders

As a person who worked on an exchange and knew about the fees being charged by exchanges to the trading companies for connectivity, data usage per kb etc, I was dumbfounded to find out about Robinhood. I just couldn't understand how they can execute trades for free.

Now that I know, it works for me. Although MMs with lot more money get to make even more money, I get to trade without fees. That 15-20 I save on every pair of buy/sell, is valuable when I am making bunch of trades every day.