How does the persistence factor work in the residual income model's continuing value, and what drives it?

The persistence factor is one of the more nuanced concepts in CFA Level II equity valuation. It addresses a fundamental economic question: how long can a company sustain abnormal profitability?

Residual Income Basics

Residual Income (RI) = Net Income - (Equity Charge)

RI = NI - (r_e x B_{t-1})

Where r_e is the cost of equity and B is book value. Positive RI means the company earns more than its cost of equity -- it creates economic value.

The Continuing Value Problem

After your explicit forecast period (say, 5 years), you need to estimate the present value of all future residual income. The persistence factor model handles this:

CV_T = (omega x RI_T) / (1 + r_e - omega)

Where omega ranges from 0 to 1:

Worked Example: Prestwick Luxury Holdings (fictional)

RI_5 = (0.14 - 0.10) x $40 = 0.04 x $40 = $1.60

CV_5 = (0.60 x $1.60) / (1 + 0.10 - 0.60) = $0.96 / 0.50 = $1.92

If omega were 0 instead: CV_5 = $0 (all excess returns evaporate)

If omega were 1.0 instead: CV_5 = $1.60 / 0.10 = $16.00 (ten times larger!)

What Drives Omega in Practice?

• Brand strength: A luxury brand with 200 years of heritage has high omega
• Regulatory barriers: A licensed utility or pharma patent holder has structurally protected returns
• Network effects: Platform businesses where value grows with users
• Switching costs: Enterprise software with deep integration into client workflows
• Commoditized industry: Low barriers, easy replication means omega near zero

Exam Strategy: The CFA exam won't ask you to estimate omega from scratch. Instead, it will give you omega and test whether you can compute the continuing value and interpret the economic meaning. Be prepared for sensitivity analysis -- 'if omega changes from 0.4 to 0.7, how does intrinsic value change?'

Practice residual income problems in our CFA equity question bank.