What do big funds do? Buy 50 shares a day, because they will influence the market, till they have the amount of shares they want?
Bill Gates is selling at this moment 1 MILLION shares of microsoft A DAY without really influencing the market. Some days the stock goes even higher although Gates is dumping.
Go to yahoo finance and check insider transactions on various stocks. You will find a lot of stocks with buy or sell transactions in the size of over 100.000 shares a day.
Coca Cola bought some time ago over 6.000.000 shares Keurig Green Mountain, Inc. in 1 day!
http://openinsider.com/
If you think orders like that aren't moving the price then you're kidding yourself. For Gates and KO, these are long term trades and moving the price half a percent isn't that significant; for a daytrader 0.5% is a game-changer.
On the GMCR trade, compare the charts and you'll see clearly that the order pushed the price higher.