Why residual income exists
Candidates often understand dividend discount models and free cash flow models first, then wonder why residual income deserves a separate reading.
The answer is that dividends and free cash flow can be noisy in exactly the situations where accounting book value and earnings still contain useful information.
Residual income solves that problem by starting from what shareholders already own on the balance sheet and then adding value only when the firm is expected to earn more than its required return on that equity base.
In compact form:
`Intrinsic value today = current book value + present value of future residual income`
That means the model is not asking whether the company earns accounting profit. It is asking whether the company earns enough profit to beat its equity charge.
The equity charge is the hinge of the whole model
This is the step many candidates skip mentally.
Suppose fictional medical-device company Northgate Imaging begins the year with book value per share of `40.00`. Analysts expect next year's earnings per share to be `6.40`, and the required return on equity is `11%`.
The equity charge is:
`0.11 x 40.00 = 4.40`
Residual income for the year is:
`6.40 - 4.40 = 2.00`
That `2.00` is the economic profit created for equity holders after compensating them for the capital already committed.
If the company only earned `4.40`, it would cover its required return but create no extra value beyond book value. If it earned less than `4.40`, residual income would be negative and intrinsic value would fall below what a naive price-to-book view might imply.