As a general matter, a corporation authorizes the maximum number of shares of each class of stock it will issue in its certificate of incorporation. It may not issue more shares than that without amending the certificate of incorporation to authorize the increase. Such amendments are frequently done and will likely be given retroactive effect if the issued shares are later authorized. Unauthorized common stock which is issued is not valid and may generally be returned to the corporation for a return of the consideration paid. Your mileage may vary. Consult an attorney if you have personal rights that turn on such facts.