Most company's stock would fall pretty hard if all the holders decided to sell at the same time. So although Google, say, technically has a huge float on a per

Most company's stock would fall pretty hard if all the holders decided to sell at the same time. So although Google, say, technically has a huge float on a percentage basis, because none of the big three holders (Eric Schmidt, Larry Page, and Sergey Brin) are selling any significant amount of their shares, the practical float is much lower.