Common stock and preferred stock are the two main forms of stock; however, it's also possible for companies to customize different classes of stock in any way they want. The most common reason for this is the company wanting the voting power to remain with a certain group; therefore, different classes of shares are given different voting rights. For example, one class of shares would be held by a select group who are given ten votes per share while a second class would be issued to the majority of investors who are given one vote per share.