An instrument that signifies an ownership position (called equity) in a corporation, and represents a claim on its proportional share in the corporation's assets and profits. Ownership in the firm is determined by the number of shares an individual owns divided by the total number of shares outstanding. For example, if a firm has 1000 shares of stock outstanding and an individual owns 50 of them, then he/she owns 5% of the firm. Most stock also provides voting rights, which give shareholders a proportional vote in certain corporate decisions. Only a certain type of firm called a corporation has stock; other types of firms such as sole proprietorships and limited partnerships do not issue stock. Also known as equity or stock or corporate stock.