Practitioner Notes
Stop Using Historical Beta Blindly
I see analysts pull five-year betas without questioning whether that time period actually reflects current business operations. If the company pivoted strategy two years ago, your beta calculation is incorporating data from a completely different business model. Look at what changed operationally before accepting any historical metric.
Terminal Growth Rates Need Context
Using GDP growth as your terminal rate sounds conservative until you realize you're valuing a company in a declining industry. The perpetuity assumption breaks down faster than you think. I've seen more valuation disputes arise from this single line item than almost anything else in the model.
Build Models That Audit Themselves
Your Excel file should flag inconsistencies automatically. If working capital as a percentage of revenue suddenly spikes in year three, the model should highlight it. Most errors happen because assumptions drift across tabs and nobody notices until the client meeting.