Any shareholder has a percentage ownership in the company, determined by dividing the number of shares they own by the number of outstanding shares. Although stock paperwork will always list numbers of shares, if share value is uncertain, percentage ownership is often a more meaningful number, particularly if you know or can estimate a likely valuation of the company. Even if the number of shares a person has is fixed, their percentage ownership will change over time as the outstanding shares change. Typically, this number is presented in percent or basis points (hundredths of a percent).