Shares outstanding are shares that have been authorized, issued, and purchased by investors and are held by them. They have voting rights and represent ownership in the corporation by the person that holds the shares. They should be distinguished from treasury shares, which are shares held by the corporation itself, having no exercisable rights.
Shares outstanding can be calculated as either basic or fully diluted. The fully diluted shares outstanding count includes diluting securities, such as options, warrants or convertibles.