Many people in the investment world also define residual income as revenue stemming from a passive source. This revenue is created without a direct input of effort or time. The investment itself creates addition revenues without having to be managed. Some examples include royalties, dividends, interest, and rent. Take a dividend stock for example. Once the money is invested once, it will keep producing a dividend every year without having to input additional time or resources. This concept is the Holy Grail for most investors.
In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.