Here what I found. Just so happens to have 200 in there also....? Interesting
The signs they send each other to move stock prices.
Many traders believe that market makers will "signal" moves in advance by using small amounts of buys or sells as "signals". The "signals" are from one market maker to another. 100 I need shares. 200 I need shares badly, but do not take the stock down.
Market Data 
Markets 
AI
