"In fact there is a SEC rule concerning the purchases of shares, that is acknowledgement of such purchases. It is called the 5 % rule.

After purchasing 5% of the shares of a company it must be reported to the SEC and then it is part of the record. Some companies only buy just under the 5% to avoid reporting."

I traded in Raptor Networks Technologies for a couple of years. There was a hedge fund owner, the main financier of Raptor, who maintained just under 10% ownership of the company. The guy owned warrants, as well. Like 20 million shares worth. Unless his transactions were large....I never saw his published trading activity. Then, again, the hedge fund was headquartered off-shore.