Worth noting (and I recently concluded this) that just because a MMS (say NITE) sits on both the top of the BID and the ASK, doesn't mean it is manipulation by a manipulator... If TD Ameritrade trades through NITE, you and I could both be using TD Ameritrade, you are the highest bidder, me the lowest seller, and you would cause NITE to be on the top of the BID, me cause NITE to be the top of the ASK... NITE thuse would top both and it is all genuine trading, no manipulation...
Typically I call it manipulation when you see painting 1 color or another (green or red) with such a small purchase/sale of shares... Of someone bought 400 shares for $0.08/share just to paint a LAST price down from $0.085 let's say, the new LAST price will be $0.08, red by $0.005 all for a purchase that costed $32 + commission... Especially so if it repeatedly happens... Sometimes also noticable if they constantly make their moves in similar block sizes (always buys 10,200 shares for example)...
Not every wall is manipulation either... Could just be a number of people buying or selling... If 50 people using TD Ameritrade (again let's say through NITE) are all trying to sell 10,000 shares each at the same time for $0.085, then a wall of 500,000 could appear on the ASK at $0.085 as NITE... Which is why sometimes walls come down after a few purchases, etc...
Also note, just because it appears there is 10,000 shares available on the ASK for $0.085, and 10,000 for $0.09 and 250,000 for $0.095, doesn't mean there is only 20,000 share standing between now and $0.095.... for example, if NITE is the one showing 10,000 shares at $0.085, other sellers using NITE might also be at $0.087 for example, but they won't show up until the $0.085 shares go away (whether removed or bought)... So that is a way shares are hidden on LEVEL 2...
Just an FYI, I recently learned some of this the past few weeks myself.
