What is a typical WACC for different industries?

Utilities and mature infrastructure: 5-7%. Mature industrial and consumer goods: 8-10%. Financial institutions: 8-11%. Growth technology: 12-15%. Emerging market companies: 15-25%+. These are rough ranges; specifics depend on leverage and business risk.

Why is the tax adjustment important for WACC?

Interest on debt is tax-deductible. If a company pays 5% interest and its tax rate is 25%, the government effectively reimburses 25% of the cost through lower taxes. The net after-tax cost is 5% × (1 - 0.25) = 3.75%. This tax shield makes debt cheaper and reduces WACC. Equity dividends are not tax-deductible, so no tax adjustment applies to cost of equity.

What happens to WACC if leverage increases?

As debt (D) increases relative to equity (E), the weight of debt in WACC increases. If debt is cheaper than equity (due to the tax shield), WACC initially decreases. However, as leverage increases, both debt and equity become riskier, and both cost of debt and cost of equity increase. Eventually, WACC bottoms out and then increases if leverage becomes too high.

What is beta and where does it come from?

Beta measures systematic risk — how much a stock moves with the overall market. β = 1 means it moves with the market. β > 1 means more volatile. β < 1 means less volatile. Beta is calculated by regressing a company's stock returns against market returns over a historical period (typically 3-5 years). It's available from Bloomberg, CapitalIQ, and Yahoo Finance. For private companies, use an unlevered beta from comparable public companies and relever it for the target's capital structure.

What is the risk-free rate and how do I determine it?

The risk-free rate is the yield on long-dated government bonds (for a UK company, use gilt yields). It represents the return on a theoretically risk-free investment. Use the current yield (not historical average) matching the duration of your analysis (for a 5-year DCF, use the 5-year gilt yield; for terminal value, use 10+ year gilt yield). Current rates are available from Bloomberg or central bank websites.

What is the difference between levered and unlevered beta?

Levered beta includes the effect of financial leverage (debt). Unlevered beta excludes leverage effects and reflects only business risk. When comparing companies with different leverage, use unlevered betas. Unlever using: β_unlevered = β_levered / (1 + (1-T) × (D/E)). Relever for your target: β_levered = β_unlevered × (1 + (1-T) × (D/E)).

Technical Interview Guide

WACC (Weighted Average Cost of Capital) Interview Questions & Walkthrough

Q: What is the risk-free rate and how do I determine it?

The risk-free rate is the yield on long-dated government bonds (for a UK company, use gilt yields). It represents the return on a theoretically risk-free investment. Use the current yield (not historical average) matching the duration of your analysis (for a 5-year DCF, use the 5-year gilt yield; for terminal value, use 10+ year gilt yield). Current rates are available from Bloomberg or central bank websites.

Q: What is the difference between levered and unlevered beta?

Levered beta includes the effect of financial leverage (debt). Unlevered beta excludes leverage effects and reflects only business risk. When comparing companies with different leverage, use unlevered betas. Unlever using: β_unlevered = β_levered / (1 + (1-T) × (D/E)). Relever for your target: β_levered = β_unlevered × (1 + (1-T) × (D/E)).

Step-by-step explanation, real interview questions, model answers at different levels, and AI-scored practice.

Quick answer

WACC is the blended cost of debt and equity capital weighted by their proportions in the capital structure. Formula: WACC = (E/V × Re) + (D/V × Rd × (1-T)), where E = equity value, D = debt value, V = total value, Re = cost of equity (from CAPM), Rd = cost of debt, T = tax rate. WACC is the discount rate in DCF analysis.

Step 1

Why WACC matters and what it represents

WACC is the discount rate used to bring future cash flows to present value. It represents the minimum return required by all capital providers — both debt holders (who demand interest) and equity holders (who demand a return on their investment). If a company's WACC is 10%, projects generating less than 10% return are value-destructive; projects generating more than 10% are value-accretive.

WACC varies by company based on business risk and financial risk. A stable utility with predictable cash flows and low leverage might have a WACC of 6-7%. A high-growth tech company with high leverage might have a WACC of 12-15%. The cost of capital reflects the risk profile of the business and its capital structure.

Small changes in WACC have outsized effects on valuation. A 1% change in WACC can move a DCF valuation by 15-25%. This is why WACC assumptions are critical and should be stress-tested. In interviews, you must be able to justify each component of WACC.

Step 2

Step 1 — Calculate cost of equity using CAPM

Cost of Equity (Re) = Rf + β × (Rm - Rf), where Rf = risk-free rate, β = beta (company's systematic risk), Rm = expected market return. The risk-free rate is typically the yield on long-term government bonds (UK gilt yield, usually 3-5%). The market risk premium (Rm - Rf) is typically 5-7% (the excess return of the stock market over risk-free rate).

Beta measures systematic risk — how much the company's stock moves with the market. A beta of 1.0 means the stock moves with the market. Beta > 1 means the stock is more volatile (higher risk, higher required return). Beta < 1 means the stock is less volatile. For mature stable companies, beta is 0.7-1.0. For growth companies, beta is 1.2-1.5+.

Example: If Rf = 4%, β = 1.2, and Rm = 11% (so market risk premium = 7%), then Re = 4% + 1.2 × 7% = 12.4%. This is the return equity holders require. Cost of equity varies based on leverage and business risk — a more leveraged company typically has higher beta and higher cost of equity.

Step 3

Step 2 — Calculate cost of debt and the tax effect

Cost of Debt (Rd) is the yield on the company's debt. For public debt, it's straightforward — the bond yield is the cost of debt. For private debt or loans, use the interest rate. For a company with £100m of debt at 5% interest, Rd = 5%. However, interest is tax-deductible, so the after-tax cost of debt is Rd × (1 - Tax Rate).

The tax shield is valuable. If a company pays 5% interest on £100m debt, the annual interest is £5m. But if the corporate tax rate is 25%, the government reimburses (via lower taxes) 25% of that cost = £1.25m. The net cost to the company is £3.75m, or 3.75%. After-tax cost of debt = 5% × (1 - 0.25) = 3.75%.

Use the after-tax cost of debt in the WACC formula. This reflects the economic reality that debt is cheaper due to the tax deductibility of interest. Equity is not tax-deductible, so no tax adjustment applies to the cost of equity.

Step 4

Step 3 — Calculate capital structure weights

The weights E/V and D/V represent the proportion of equity and debt in the capital structure. V = E + D (total value). If a company has £500m of equity value and £300m of debt value, then V = £800m, E/V = 62.5%, D/V = 37.5%.

Use market values, not book values. Book value (from the balance sheet) is accounting-based and can be materially different from market value. For a public company, use market cap for equity value. For debt, use the market value of bonds (or estimate by assuming debt is fairly valued at par).

For a private company or when modelling a forward valuation, you might use a target or assumed capital structure. Example: assume a 40% debt, 60% equity structure going forward. Use those weights in WACC.

Step 5

Step 4 — Calculate WACC and sensitivity test

WACC = (E/V × Re) + (D/V × Rd × (1-T)). Example: E/V = 60%, Re = 12%, D/V = 40%, Rd = 5%, Tax Rate = 25%. WACC = (0.60 × 12%) + (0.40 × 5% × (1-0.25)) = 7.2% + 1.5% = 8.7%. This is the discount rate you'd use in the DCF.

Always stress-test WACC. Run sensitivity on cost of equity (vary Rf, β, market risk premium by ±0.5-1.0%). Run sensitivity on cost of debt (current rates might be elevated; consider 2-3% variance). Run sensitivity on capital structure (leverage might change post-acquisition or during the projection period). A ±1% change in WACC should change DCF valuation by 15-25%.

Document your WACC assumptions clearly. Show the inputs: risk-free rate (date sourced, which bond), beta (sourced from Bloomberg/CapitalIQ, peer average), market risk premium (your justification), cost of debt (source), tax rate, and capital structure. This allows investors and deal partners to audit your work.

Questions

WACC (Weighted Average Cost of Capital) interview questions

1What is WACC and why is it important in valuation?
2Walk me through the WACC calculation.
3What is beta and how do you calculate cost of equity?
4What is the tax shield in WACC and why does it matter?
5How would you calculate the cost of debt?
6What is the capital structure and how do you determine weights?
7Should you use book value or market value in WACC?
8What is the risk-free rate and how do you determine it?
9What is the market risk premium and what is a reasonable range?
10If WACC increases by 1%, what happens to DCF valuation?
11How would you adjust WACC for a leveraged buyout?
12Walk me through the sensitivity analysis on WACC.
13What is an unlevered beta and when would you use it?
14How would you estimate WACC for a private company?

Model answers

Example answers at different levels

Click a level to see the expected answer depth.

Question

Walk me through WACC.

Answer

WACC is the blended cost of debt and equity. You calculate the cost of equity using CAPM — that's risk-free rate plus beta times the market risk premium. Then you calculate the cost of debt, which is the interest rate the company pays. You weight these by the proportion of debt and equity in the capital structure. So if the company is 60% equity and 40% debt, WACC = 60% × cost of equity + 40% × cost of debt × (1 minus tax rate). The tax adjustment applies because interest is tax-deductible. WACC is the discount rate you use in a DCF.

Intervyo Learn

Master WACC (Weighted Average Cost of Capital) inside out

Intervyo Learn offers 12 structured courses covering every technical topic you'll face in interviews. WACC (Weighted Average Cost of Capital) is covered in depth in the Investment Banking course — from fundamentals to the follow-up questions that trip up most candidates.

Explore Intervyo Learn

Free for 3 days · No card charged until trial ends · Cancel anytime

Follow-ups

Common follow-up questions

If the company refinances debt at a lower rate, how does that change WACC?

How would you calculate WACC for a company in a different country or industry?

If the company increases leverage, what happens to WACC?

How would you adjust WACC if the company plans a major acquisition?

What is an unlevered beta and when would you use it to calculate levered beta?

If interest rates rise 2%, how would that affect your WACC?

How would you estimate cost of equity for a private company with no comparable public comparables?

Avoid

Common mistakes on wacc (weighted average cost of capital) questions

Using book value instead of market value for capital structure. Book value of debt might differ from market value (especially in a changing interest rate environment). Use market values for both equity and debt.

Forgetting the tax adjustment on cost of debt. After-tax cost of debt = Rd × (1 - Tax Rate). Interest is deductible, so the net cost is lower. Ignoring this overstates WACC.

Using an outdated risk-free rate. The yield on government bonds changes with interest rates. Use current yields, not historical averages.

Not adjusting beta for leverage. A company's beta changes with leverage. If comparing a levered company to an unlevered peer, unlever the peer's beta and relever it for your target's capital structure.

Applying the same market risk premium globally. Market risk premiums vary by country and market. UK, US, and emerging markets have different premiums.

Not sensitivity testing WACC. WACC is the biggest value driver in a DCF. Always show a range with ±1% sensitivity. A single WACC number suggests overconfidence.

Firms

Which firms ask wacc (weighted average cost of capital) questions?

Goldman Sachs

Tested across all divisions. WACC calculation and sensitivity analysis expected. Emphasis on clear assumptions.

Morgan Stanley

Core technical skill. Deep understanding of beta, cost of debt, and leverage effects required.

JP Morgan

WACC mastery expected for DCF and valuation work. Beta sourcing and adjustment tested.

McKinsey

Case interviews may ask WACC context. Understand cost of capital and discount rate concepts.

Lazard

Rigorous testing of WACC mechanics, especially leverage adjustment and tax treatment.

Evercore

Strong emphasis on assumptions and sensitivity. WACC clarity non-negotiable.

FAQ

WACC (Weighted Average Cost of Capital) FAQs

Master every technical topic

AI-scored practice across DCF, LBO, valuation, M&A, and 16 more technical topics. Firm-specific questions with detailed feedback.

Start free trial

Free for 3 days · No card charged until trial ends · Cancel anytime