Unissued stock are company shares that do not circulate, nor have they been put up for sale to either employees or the general public. As such, companies do not print stock certificates for unissued shares. Unissued shares are normally held in a company's treasury. Their number typically has no bearing on shareholders.
Calculation of Unissued Stock
To calculate the amount of unissued stock, subtract the total number of shares outstanding from the total number of authorized shares, and also subtract the number of shares of treasury stock. For example, a business has 1,000,000 authorized shares, 100,000 shares outstanding, and 10,000 shares of treasury stock. The unissued stock is calculated as follows:
1,000,000 Authorized shares - 100,000 Shares outstanding - 10,000 Treasury shares = 890,000 Unissued shares
Unissued stock has never even been printed on a stock certificate. It is more of a theoretical number of shares that could be issued, rather than an actual legal document.
Unissued Stock and Treasury Shares
Unissued shares are different from treasury shares which were shares sold and repurchased by the company. Regardless that treasury shares and unissued shares are not the same, some companies classify repurchased shares as unissued shares. Shares that have been authorized for use in a company's charter but are yet to be issued are unissued shares. In 2014, Family Dollar Stores filed a 10k with SEC where they stated that Shares purchased under the share repurchase authorizations are generally held in treasury or are canceled and returned to the status of authorized but unissued shares. Hence, to calculate the number of unissued stock, the total number of authorized for issuance is deducted from the total amount of shares outstanding, and treasury stock shares.