Every minute there is another 500 share exchange between the same two houses. Have experienced this before and it always seemed a precursor to someone wanting to do a "take out". By keeping the price surpressed the usual "premium" on take over is kept to a minimum.
Always more fun and usually more profitable for the retail investor if the market functions in a normal capacity but I guess that is just a fact of life when we play the "big casino".
Onward and Upward