RE:RE:RE:RE:RE:RE:RE:RE:Tell Me Again Oops forgot the sneakiest one. ATS otherwise known as dark pool trading. This somehow allows the illegal practice of naked shorting masked with legal MM/House liquidity . It's supposed to just be for liquidity . Produce a share for the buyer whether you have it or not then quickly "cover" it by replacing it as quick as possible. This shouldn't lead to profit but what happens when a broker produces a dark pool share for you (out of thin air not even from pool of shares that can be shorted) and just waits around a little ? So sells you a $0.09 and covers it with an $0.085 fill. Even when they don't make profit on it it also doesn't thin the ask (or bid depending where done) or add to the seen regular volume . Profit ot not it's also a big game