DCF Sensitivity Analysis: WACC, Terminal Growth and Valuation Risk
A DCF sensitivity analysis shows how much a valuation changes when the weighted average cost of capital (WACC) and terminal growth rate change. Its purpose is not to find the most attractive cell in a spreadsheet. It is to reveal whether a decision is robust to reasonable uncertainty in the assumptions that dominate value.
This guide builds a reproducible five-year example, calculates a two-variable sensitivity matrix and turns the output into decision rules for managers and analysts.
What the sensitivity table is testing
For a standard enterprise-value DCF, the model discounts forecast free cash flow to the firm (FCFF) and a terminal value:
Enterprise value = Σ FCFF_t / (1 + WACC)^t + Terminal value / (1 + WACC)^n
Using the perpetual-growth method at the end of forecast year n:
Terminal value_n = FCFF_n × (1 + g) / (WACC - g)
where g is the terminal growth rate. The formula requires WACC > g. That mathematical condition is necessary but not sufficient: the assumptions must also make economic sense for the business, currency, inflation basis and long-run market.
WACC and terminal growth affect the same valuation in opposite directions:
- a higher WACC reduces the present value of forecast and terminal cash flows;
- a higher terminal growth rate increases terminal value;
- a smaller gap between WACC and
gmakes the terminal-value formula highly sensitive.
This article uses WACC as an input. It does not teach how to construct the discount rate; that is a separate managerial and governance decision.
Worked five-year DCF example
Assume a business is expected to generate the following FCFF, in EUR millions:
| Year | FCFF (EUR m) |
|---|---|
| 1 | 8.0 |
| 2 | 9.0 |
| 3 | 10.0 |
| 4 | 11.0 |
| 5 | 12.0 |
The base case uses:
- WACC: 10.0%;
- terminal growth: 3.0%;
- terminal value measured at the end of Year 5;
- all annual cash flows assumed to occur at period end;
- no mid-year convention, non-operating assets or enterprise-to-equity adjustments.
Step 1: discount the explicit forecast
PV of forecast FCFF = 8/1.10 + 9/1.10² + 10/1.10³ + 11/1.10⁴ + 12/1.10⁵
The result is EUR 37.19 million.
Step 2: calculate terminal value
Terminal value at Year 5 = 12 × 1.03 / (0.10 - 0.03) = EUR 176.57 million
Step 3: discount terminal value
PV of terminal value = 176.57 / 1.10⁵ = EUR 109.64 million
Step 4: calculate enterprise value
Enterprise value = 37.19 + 109.64 = EUR 146.83 million
The present value of the terminal value is 74.7% of the enterprise value. That concentration is not automatically an error, but it tells management that assumptions beyond the explicit forecast drive most of the conclusion.
The WACC–terminal-growth sensitivity matrix
Holding the five forecast cash flows constant, the following matrix recalculates enterprise value for five WACC values and five terminal growth rates. All figures are EUR millions.
| WACC \ Terminal growth | 1.0% | 2.0% | 3.0% | 4.0% | 5.0% |
|---|---|---|---|---|---|
| 8.0% | 157.2 | 178.2 | 207.6 | 251.7 | 325.2 |
| 9.0% | 136.7 | 151.9 | 172.1 | 200.5 | 243.0 |
| 10.0% | 120.8 | 132.2 | 146.8 | 166.3 | 193.7 |
| 11.0% | 108.1 | 116.9 | 127.9 | 142.0 | 160.8 |
| 12.0% | 97.8 | 104.7 | 113.2 | 123.8 | 137.4 |
The full grid ranges from EUR 97.8 million to EUR 325.2 million. That is not a probability interval. It is a map of model outputs conditional on the specified input combinations.
If management regards WACC of 9–11% and terminal growth of 2–4% as the central plausible range, the corresponding values span EUR 116.9 million to EUR 200.5 million. A proposed offer expressed on the same enterprise-value basis, or an investment threshold inside that interval, depends heavily on assumptions; an enterprise-value offer well above it demands a separate source of value or stronger evidence.
How to interpret the table without cherry-picking
1. Define the plausible range before looking at the answer
If a team adjusts the input range after seeing the valuation, the analysis becomes a negotiation with the spreadsheet. Document the range, source date, currency and rationale before reviewing the matrix.
Current valuation data published by Aswath Damodaran at NYU Stern include industry costs of capital, betas, capital structures and other reference measures. Such data can inform a benchmark, but they do not replace company-specific judgment about operating risk, financing and geography.
2. Read diagonally, not cell by cell
The bottom-left region combines a high discount rate with low terminal growth and produces lower values. The top-right combines a low discount rate with high terminal growth and produces higher values. The diagonal pattern exposes whether small joint changes move the decision materially.
3. Measure terminal-value dependence
The base case derives 74.7% of value from the discounted terminal value. Management should therefore challenge:
- whether Year 5 represents a stable operating state;
- whether margins and reinvestment can support the assumed growth;
- whether forecast FCFF and terminal growth are internally consistent;
- whether the discount rate and cash flows use consistent nominal or real terms;
- whether the forecast and terminal value double count an improvement.
4. Link the matrix to a decision threshold
A sensitivity table becomes useful when compared with a threshold:
- maximum acquisition price;
- minimum value required to approve an investment;
- carrying amount in an impairment review;
- financing capacity or covenant headroom;
- value per share after a separate enterprise-to-equity bridge.
Do not treat enterprise value as the amount available to shareholders. Debt, cash, leases, non-controlling interests and other adjustments require a separate bridge.
5. Add operating sensitivities
A WACC–growth matrix tests two valuation inputs while holding the operating forecast constant. It cannot answer what happens if revenue, margin, working capital, capital expenditure or implementation timing changes. Use a separate scenario analysis for those drivers, then run a valuation sensitivity table for each coherent scenario if the decision warrants it.
Five decision rules for DCF sensitivity analysis
| Rule | Management question | Action |
|---|---|---|
| Reject invalid combinations | Is WACC less than or equal to terminal growth? | Remove the cell; do not report a meaningless result |
| Pre-commit the range | Were inputs selected before reviewing the value? | Record sources, date and rationale |
| Focus on decision stability | Does the recommendation change within a plausible central range? | Escalate assumption risk if it does |
| Expose terminal concentration | How much value comes from the terminal period? | Challenge steady-state economics and consider a longer explicit forecast |
| Separate model layers | Are operating scenarios, discount-rate sensitivity and EV-to-equity adjustments mixed together? | Analyse and reconcile them separately |
These rules prevent a common failure: presenting a wide grid while discussing only the preferred base case.
Sensitivity analysis is not a probability model
A two-variable table says, “If WACC is X and terminal growth is Y, value is Z.” It does not say how likely X or Y is. Nor does it capture correlation: a difficult operating environment may simultaneously reduce cash flows, increase financing risk and lower sustainable growth.
For high-stakes decisions, complement the matrix with:
- downside, base and upside operating scenarios;
- break-even or switching-value analysis;
- evidence-weighted ranges for key assumptions;
- a decision tree for discrete events such as regulatory approval or product launch;
- a record of which assumptions management can influence.
The HM Treasury Green Book 2026 is written for public-sector appraisal, not corporate WACC. Its emphasis on options, discounting, risk, uncertainty and clear communication of assumptions is nevertheless a useful methodological reminder: decision-makers need to see how uncertainty changes the preferred option.
Accounting and valuation boundaries
IAS 36 Impairment of Assets describes value in use as expected future cash flows discounted to present value using an appropriate discount rate. That is a specific accounting context; it does not make every transaction DCF an IAS 36 valuation.
Similarly, IFRS 13 defines fair value as an exit price under current market-participant assumptions. A management DCF based on company-specific plans may be an intrinsic decision model, not automatically an IFRS fair-value measurement. Clarify the valuation purpose before selecting assumptions or labels.
A board-ready conclusion
A useful DCF sensitivity conclusion can be written in four sentences:
- State the base enterprise value and the assumptions that produce it.
- State the credible central range and why those inputs are credible.
- Identify the variables and terminal-value dependence that threaten the recommendation.
- State what evidence, price change or operating milestone would change the decision.
That turns a matrix from a spreadsheet exhibit into a management control.
For a broader sequence connecting financial analysis, capital budgeting, valuation and M&A, explore the Executive Certificate in Strategic Finance, M&A & Corporate Valuation.