Thanks. I'm not sure they couldn't legally get away with programming in 'encouragement' to either increase or decrease inventory based on various technical factors - maybe overall money inflows or something like that are monitored. If so, then it may be that multiple mms have similar programs which ends up creating cycles in the overall penny market. Same effect as obvious illegal collusion. Not 'evil' but still a mm-driven cycle.
Market Data 
Markets 
AI
