In any incorporated business when there is more than one owner, the ownership is usually stated in percent of ownership or shares. When the stock is set to a certain value, then you can say that one share equates to a fixed or variable dollar amount. If you belong to a credit union then you have shares in that credit union. Usually one share is equal to a fixed about. (usually one dollar) As the value of the credit union increases, the business gains additional shares and your interest is calculated in shares or fraction of a share.