See the signs and messages they send each other
Many traders believe that Market-Makers (MMs) will “signal” moves in advance by using small amounts of buys or sells as “signals”. The “signals” are from one MM to another.
This is a theory put forth by a lot of penny stock and non-penny stock traders. This is not a guaranteed trading method but can lend some insight to communications. It can pay to watch a few MMs so you can divine what they are going to do and jump in ahead of any move that may come.