let me ask you a question lights. please answer specifically.
1) exactly how should market makers (hft's whatever you want to call them) have handled may 6th with market orders coming down the pipe on ALL their stocks sweeping the book down 10-90%+ in seconds?
2) do you know what an ISO is? this was the primary tool used on the 6th, and they resulted in FILLS, not pulls.
you asked me if i did the research... i actually have. i had to research it, because i traded it and it was a fantastic example of an intraday black swan.
market makers got STUFFED that day. across the board in EVERYTHING. i trade full-auto prop, making markets, and i can say that I got completely STUFFED that day, capital completely maxed out (too early btw), and sat through a period of complete chaos until those sellers let up.
it wasn't about pulling bids, it was about sellers DESTROYING bids, DESTROYING bid books all the way down in a blink. over and over. in minutes and seconds. EVERYTHING. you couldn't even hedge. the fckin spoo pit was 10 handles spread! 10 HANDLES! why?! because they'd swept that too!
if you were making markets that day, you would KNOW. it wasn't as one-sided as you make out to be.