Equity Interests are ownership interest in a business entity, from the concept of equity as ownership. For example, if an investor owned a 10% interest in a partnership which owned a property with a market value of $1,000,000 and was subject to a $500,000 mortgage, then the investor would have an equity interest of $50,000 in the partnership ($1,000,000 value less $500,000 debt equals $500,000 times 10% equals $50,000).