An ownership interest in an entity. Broadly, equity interest refers to ownership interest of investor-owned entities, which is evidenced by holding a specific number of shares of stock (equity instruments). In the context of mutual entities, equity interest is used to mean ownership interest of owners, members or participants in an entity. Such an interest is manifested by means of holding shares in the respective entity (e.g., a share in a mutual fund).

An equity interest does not include other holdings or instruments that are treated as indebtedness (debt instruments). Examples of equity interest are profit-sharing interest in a partnership, an undivided ownership interest in a pool of assets, and a beneficial interest in a trust.