A shareholder (also stockholder) is an individual or institution (including a corporation) that legally owns one or more shares of stock in a public or private corporation. Shareholders may be referred to as members of a corporation. Legally, a person is not a shareholder in a corporation until their name and other details are entered in the corporation's register of shareholders or members. A shareholder (also stockholder) is an individual or institution (including a corporation) that legally owns one or more shares of stock in a public or private corporation. Shareholders may be referred to as members of a corporation. Legally, a person is not a shareholder in a corporation until their name and other details are entered in the corporation's register of shareholders or members.