How to Calculate Beta: A Step-by-Step Guide for Investment Banking Interviews

Max

June 20, 2026

Share this post:

Beta is one of those concepts that comes up constantly in investment banking interviews, yet most candidates struggle to explain it clearly. Whether you’re walking through a DCF analysis, calculating WACC, or discussing the cost of equity using CAPM, you need a rock-solid understanding of beta and how to calculate it.

In this guide, we’ll break down everything you need to know about beta for investment banking interviews, from the basic definition to the Hamada equation to practical tips for relevering beta in a comparable companies analysis. If you’re serious about landing an IB offer, this is must-know material.

Table of Contents

What Is Beta?

At its core, beta measures the systematic risk of a stock relative to the overall market. A beta of 1.0 means the stock moves in lockstep with the market. A beta greater than 1.0 means the stock is more volatile than the market, and a beta below 1.0 means it’s less volatile.

Here’s a quick reference:

Beta = 1.0: The stock moves exactly with the market
Beta > 1.0: The stock is more volatile (e.g., high-growth tech companies)
Beta < 1.0: The stock is less volatile (e.g., utilities, consumer staples)
Beta = 0: The asset has no correlation with market movements (e.g., risk-free assets)
Negative Beta: The asset moves inversely to the market (rare, but possible)

Beta is a critical input in the Capital Asset Pricing Model (CAPM), which is the most common method for calculating the cost of equity. The CAPM formula is:

Cost of Equity = Risk-Free Rate + Beta x (Market Risk Premium)

So if you get beta wrong, your entire cost of equity (and by extension, your WACC calculation) will be off. That’s why interviewers love testing this concept.

Levered Beta vs. Unlevered Beta

This is where most interview candidates start to trip up. There are two types of beta you need to understand:

Levered Beta (Equity Beta)

Levered beta reflects the risk of a company’s equity, including the effects of its capital structure (i.e., its debt). When you look up a stock’s beta on Bloomberg, Yahoo Finance, or Capital IQ, you’re seeing the levered beta. It captures both the business risk and the financial risk from leverage.

More debt means more financial risk for equity holders, so levered beta increases as a company takes on more debt. Think of it this way: if a company is financed entirely with equity, its levered and unlevered betas are the same. But as it adds debt, the equity becomes riskier because debt holders get paid first in a liquidation, making the equity claim more volatile.

Unlevered Beta (Asset Beta)

Unlevered beta strips out the impact of the capital structure and reflects only the business risk of a company: the risk inherent to its operations regardless of how it’s financed. This is useful when comparing companies with different capital structures, which is exactly what you do in a comparable companies analysis.

When you’re building a DCF model, you typically unlever the betas of comparable companies, take the median, and then relever that beta using the target company’s capital structure. This gives you a beta that reflects the business risk of the peer group but the financial risk of the specific company you’re valuing.

The Hamada Equation: Unlevering and Relevering Beta

The Hamada equation is the standard formula used to convert between levered and unlevered beta. Here’s how it works:

Unlevering Beta

Unlevered Beta = Levered Beta / [1 + (1 − Tax Rate) x (Debt / Equity)]

This removes the effect of the company’s capital structure. You start with the observed levered beta and divide by the leverage adjustment factor.

Relevering Beta

Relevered Beta = Unlevered Beta x [1 + (1 − Tax Rate) x (Debt / Equity)]

This applies the target company’s capital structure to the unlevered beta. You’re essentially saying, “Given this level of business risk, how risky would the equity be if the company had this specific debt-to-equity ratio?”

Worked Example

Let’s say you have three comparable companies:

Company A: Levered Beta = 1.3, D/E = 0.5, Tax Rate = 25%
Company B: Levered Beta = 1.1, D/E = 0.3, Tax Rate = 25%
Company C: Levered Beta = 1.5, D/E = 0.8, Tax Rate = 25%

Step 1: Unlever each beta.

Company A: 1.3 / [1 + (1 − 0.25) x 0.5] = 1.3 / 1.375 = 0.95
Company B: 1.1 / [1 + (1 − 0.25) x 0.3] = 1.1 / 1.225 = 0.90
Company C: 1.5 / [1 + (1 − 0.25) x 0.8] = 1.5 / 1.60 = 0.94

Step 2: Take the median unlevered beta. The median is 0.94.

Step 3: Relever using the target company’s capital structure. If the target has a D/E of 0.4 and a tax rate of 25%:

Relevered Beta = 0.94 x [1 + (1 − 0.25) x 0.4] = 0.94 x 1.30 = 1.22

You would then use 1.22 as your beta in the CAPM formula to calculate cost of equity.

Where to Find Beta Data

In practice, analysts source beta from several places:

Bloomberg Terminal: The gold standard. Use the BETA function (or the Beta tab on a company’s equity page). Bloomberg lets you adjust the regression period and benchmark index.
Capital IQ / FactSet: Both platforms provide levered and unlevered betas along with historical data.
Yahoo Finance: Free and accessible. Lists beta on the “Statistics” page for any public stock. However, the methodology is less transparent.
Damodaran’s Website: Professor Aswath Damodaran at NYU publishes industry-average unlevered betas annually. This is a great free resource if you don’t have terminal access.
Regression Analysis: You can calculate beta yourself by regressing a stock’s returns against a market index (like the S&P 500) over a given period, typically 2-5 years of weekly or monthly returns.

Raw Beta vs. Adjusted Beta

You might see two versions of beta when you look up a stock:

Raw Beta is the pure regression output, the slope coefficient from regressing the stock’s returns against the market returns.

Adjusted Beta (also called the Blume-adjusted beta) incorporates the assumption that betas tend to revert toward 1.0 over time. The formula is:

Adjusted Beta = (2/3 x Raw Beta) + (1/3 x 1.0)

Bloomberg uses adjusted beta by default. Most bankers also use adjusted beta, but you should know both and be prepared to discuss why mean reversion might or might not apply in a given situation.

Why Beta Matters for WACC and DCF

Beta feeds directly into the cost of equity via CAPM, and the cost of equity is a key component of WACC (Weighted Average Cost of Capital). WACC is the discount rate you use in a DCF analysis to discount free cash flows back to present value.

If beta is too high, the discount rate will be too high, and the DCF will undervalue the company. If beta is too low, the opposite happens. Getting beta right is essential for arriving at a defensible valuation, which is exactly what your interviewers want to see you demonstrate.

Understanding enterprise value vs. equity value is also critical here, since the DCF yields enterprise value, and you need to bridge to equity value to arrive at a share price. The choice of beta and discount rate directly impacts that final number.

Common Interview Questions About Beta

Here are questions you should be prepared to answer:

“What is beta and what does it measure?”: Beta measures the systematic (non-diversifiable) risk of a stock relative to the market.
“Walk me through how you would calculate beta for use in a DCF.”: Identify comparable companies, get their levered betas, unlever using Hamada equation, take the median, relever using target’s capital structure.
“What happens to beta when a company takes on more debt?”: Levered beta increases because equity holders bear more financial risk. Unlevered beta stays the same (business risk hasn’t changed).
“Would you use a 2-year or 5-year beta?”: It depends. A 5-year beta provides a larger sample but may include outdated data if the company has changed significantly. A 2-year beta is more current but can be noisy. Most banks use 2-year weekly or 5-year monthly.
“A company just completed a major acquisition. How does that affect beta?”: The historical beta may no longer reflect the combined entity’s risk profile. You might want to weight the betas of the acquirer and target based on their respective enterprise values, or use a shorter lookback period post-deal.
“Why might you use an industry beta instead of a company-specific beta?”: For smaller or recently public companies, the company-specific beta may be unreliable due to thin trading or short history. An industry median unlevered beta can be more stable and representative.

Practical Tips for Beta in Interviews

Always specify which beta you mean. When discussing beta, clarify whether you’re talking about levered or unlevered. Precision matters.
Know the formula cold. The Hamada equation is a favorite whiteboard question. Practice writing it out quickly and explaining each component.
Connect it to the bigger picture. Beta doesn’t exist in a vacuum: link it back to CAPM, cost of equity, WACC, and ultimately the DCF. Interviewers want to see that you understand the full chain.
Be ready to defend your choices. If an interviewer asks why you used a 2-year weekly beta instead of a 5-year monthly, you need a thoughtful answer. There’s no single “right” answer: it’s about demonstrating sound judgment.
Understand the limitations. Beta is backward-looking and assumes that past volatility predicts future risk. In reality, a company’s risk profile can change dramatically due to acquisitions, divestitures, or shifts in its business model.

Key Takeaways

Beta is a foundational concept that connects to nearly every major valuation topic you’ll encounter in investment banking interviews. Mastering it means understanding not just the formula, but the intuition behind levered vs. unlevered beta, the Hamada equation, and how beta flows through to WACC and DCF. Make sure you can walk through a full worked example and explain your reasoning at each step.

If you want to take your technical preparation to the next level, check out our free resources page and our technical cheatsheet: they cover all the core formulas and concepts you need to know. And for a deeper dive into related topics, explore our guides on how to calculate cost of equity and how the three financial statements link together.

Want Personalized Interview Coaching?

At Wall Street Mastermind, we’ve helped over 2,500 students land offers at top investment banks, private equity firms, and hedge funds. Our coaches have firsthand experience at the most prestigious firms on Wall Street and can help you master every technical concept, from beta to LBOs to merger models. Apply today to see how we can help you break into investment banking.

Follow Wall Street Mastermind

Podcast: Apple Podcasts | Spotify | SoundCloud

Share this post:

About the Author

Max

Max Adams is the Head Coach of Wall Street Mastermind, the premier investment banking mentoring program. Max began his career in investment banking at Lazard and Qatalyst Partners -- two of the most prestigious advisory boutiques on Wall Street -- before moving into technology private equity at Vector Capital. Afterward, Max earned an MBA from Stanford GSB while completing a joint degree at the Harvard Kennedy School. Wall Street Mastermind has guided over 2,500 students into top finance careers since 2018. Connect with Max on LinkedIn or follow @wallstreetmastermind on Instagram.