is to save up a block of shares (say in the .86 range), from earlier trading and don't print them. Then when trading jumps up to .90, but slows down somewhat... The MM's introduce those same shares as fresh trades to create the appearance of a sell down. This fake sell down, can then be self-fulfilling, and thus feed on itself.
Iwonder, the buyers at .86, .865, .87 are investors. Their broker is one of the MMs who turns to the broker ( MM ) trying to execute the .855 sell order. The brokers ( MMs) keep the margin between .855 and .86 or .865 or .87