If you have queries about flows from a US broker to market makers, you can look for the 606 and 607 reports on their website. e.g. https://robinhood.com/us/en/a

If you have queries about flows from a US broker to market makers, you can look for the 606 and 607 reports on their website. e.g. https://robinhood.com/us/en/about/legal/ https://robinhood.com/us/en/about/legal/ "you need to handle that case explicitly .. order books used to serve that role: i’m not sure what the solution is in this era of HFT." This is addressed by a Smart Order Router.