Two things I've noticed about MMs. My trades go
Post# of 82672
My trades go through one MM (CSTI) for one stock, and NITE or CDEL or xxxx for different stocks, so even one brokerage used different MMs.
Also, my brokerage firm allows me to specify which MM to use, if I so desire. Never tried that, and suspect there may be an additional fee to use that feature.
Need to run out for a bit, so won't be able to respond to replies right away.
Best of luck to all.