Insiders sell for many reasons, but buy for one reason only, to make money. They may buy if they believe their stock is to cheap or if they believe the company's outlook is better than what the investment community forecasts.

Insiders are defined as company's officers and directors, and any beneficial owners of more than 10% of a class of the company's equity securities. Insiders must file with the SEC a statement of ownership regarding those securities. An insider of an issuer that is registering equity securities for the first time must file a Form 3. Changes in ownership are reported on Form 4 and must be reported to the SEC within two business days under most conditions.