Insider Buying - Insider buying is the buying of a company or corporation's common stock certificates by an individual director, or executive. It is the buying of a company or corporation's common stock certificates by other company employees. Generally an indication that those individuals involved believe that the company stock or corporation stock is undervalued. This is a practice that borders on illegal practices if the insider information is the reason for the purchasing of the stock certificates. It is the opposite of the insider selling practice. It is an officer of a company with access to private information about the company operation.