Stock: The term stock is also used to mean the ownership shares of a corporation. For example, an owner of a corporation will have a stock certificate which provides evidence of his or her ownership of a corporation's common stock or preferred stock. Bond: A bond could be a formal debt instrument issued by a corporation or government and purchased by investors. This is the meaning when we say that a public utility issued or sold bonds to help finance a new power plant. Investors talk about investing in stocks and bonds.