Build-Up Method (Cost of Equity)

The build-up method (or “build-up approach”) for estimating cost of equity is additive and transparent. Rather than using regression to estimate a single beta (as in CAPM), you explicitly identify risk premiums and add them: start with the risk-free rate, add an equity risk premium, add a size premium for small companies, add a company-specific premium for unique risks. The result is a cost of equity grounded in logic rather than backward-looking regression.

The formula

Cost of equity = Risk-free rate + Market risk premium + Size premium + Company-specific premium

Or more generally:

Cost of equity = Risk-free rate + (Premium 1) + (Premium 2) + (Premium 3) + …

Components

Risk-free rate. The yield on a government bond. Typically a 10-year Treasury for long-term valuations. 3–5% in normal times.

Market (equity) risk premium. The excess return investors demand for holding equities instead of risk-free bonds. 5–7% based on historical data, or lower if forward-looking estimates are used. This is essentially CAPM’s market risk premium, added directly rather than multiplied by beta.

Size premium. Small companies are riskier and earn higher returns. A company with market cap below 100 million might earn 2–4% extra annually. A company with market cap over 1 billion might earn 0–1% extra.

Company-specific premium. Risks unique to the company not captured by size or market factors:

• Key-person risk (one executive is crucial)
• Customer concentration (a few large customers)
• Product concentration (one product is 80% of revenue)
• Competitive threats
• Technology or regulatory risks

The premium might be 1–5%, depending on the risk.

Example

A small, regional software company:

Risk-free rate: 4% Market risk premium: 6% Size premium (market cap 50 million): 3% Company-specific premium (dependent on one key product): 2% Total cost of equity: 4% + 6% + 3% + 2% = 15%

Compare to CAPM: if the company’s beta is 1.4, cost of equity = 4% + 1.4×6% = 12.4%.

The build-up method (15%) yields a higher cost of equity, reflecting the specific risks better.

Advantages

Transparency. Each risk is explicit. You can see exactly why cost of equity is 15% (market risk, size, company risk). With CAPM beta, the calculation is abstract.

Flexibility. You can add premiums for specific risks. A mining company might add commodity-price risk. A bank might add interest-rate risk.

Avoids regression noise. CAPM betas, estimated via regression, are noisy and change over time. Build-up is more stable because it is conceptual, not backward-looking.

Better for private companies. For private firms without traded securities, running a regression to get beta is impossible. Build-up works: estimate size (compare to public companies of similar size) and add premiums.

Disadvantages

Subjectivity in premiums. What is the appropriate size premium for a 50 million-dollar company? 3% or 4%? What is the company-specific premium? 1% or 3%? Different analysts get different answers.

Risk of double-counting. If you add a company-specific premium for “customer concentration,” are you also implicitly adding that risk in the market risk premium? Care is needed to avoid overlap.

Lack of market discipline. CAPM beta comes from the market (observed from stock returns). Build-up premiums are your estimates. The market doesn’t constrain them.

Less widely accepted. Most investment banks and analysts use CAPM or Fama-French. Build-up is less standard, so presenting it requires more justification.

Practical build-up framework

For any company:

• Start with risk-free rate (10-year Treasury).
• Add market risk premium (5–7%, based on historical or forward-looking data).

For small companies (under 500 million market cap):

• Add size premium (1–4% depending on size).

For any company with elevated risk:

• Add company-specific premium (0–5% depending on risks):
  • Key-person risk: +0.5–1.5%
  • Customer concentration (top 3 customers > 50% of revenue): +0.5–1.5%
  • Product concentration: +0.5–1%
  • Emerging market or high-regulatory risk: +1–3%
  • Technology or disruption risk: +0.5–2%
  • Leverage risk (highly leveraged): +0.5–2%

For mature, stable, low-risk companies:

• Use risk-free + market premium only, perhaps no size premium or minimal.

Reconciling build-up with CAPM

A build-up of 15% can be reconciled with CAPM by backing out an implied beta:

15% = 4% + Beta × 6% Beta = (15% - 4%) / 6% = 1.83

So the build-up method, applied to a company with risk-free 4% and market risk premium 6%, is equivalent to assuming beta of 1.83. Is that reasonable for the company? If the company is highly volatile, 1.83 might be right. If not, the build-up might be too high.

This cross-check is useful: if build-up and CAPM yield very different results, investigate why.

When build-up is most useful

Private company valuation. No market beta available; build-up is natural.

Early-stage or risky companies. Company-specific premiums capture concentrated risks better than a single beta.

Small-cap or specialized companies. Standard beta estimates are unreliable; build-up is more defensible.

Non-profit or valuation for internal purposes. When transparency and logic matter more than market convention.

When CAPM or Fama-French is better

Large, publicly traded companies. Market betas are reliable; standard models are accepted.

When you need market discipline. If you are valuing for investors, using market-based betas is more credible than subjective premiums.

Speed and simplicity. CAPM is faster than estimating multiple premiums.

See also