Watching the trades go through you may sometimes notice very smal executions. Some people believe, and remember this is just a theory, those small numbers could be the market maker signals to each other...
100 I need shares.
200 I need shares badly, but do not take the stock down.
300 Take the price down so I can load shares
400 Keep trading it sideways.
500 Gap the stock. This gap can be either up or down, depending on the direction of the 500 signal.
Don't be manipulated by the manipulators!