To calculate debt beta, subtract the risk-free rate from the company’s cost of debt and divide the result by the equity risk premium. That single division gives you a figure that scales the company’s credit risk against the systematic risk of the broader equity market. Most investment-grade corporate debt lands between 0.05 and 0.30; high-yield bonds often push above 0.40.
The Formula
Debt beta is the Capital Asset Pricing Model rearranged to isolate beta for a company’s debt rather than its equity:
Debt Beta = (Cost of Debt − Risk-Free Rate) / Equity Risk Premium
The numerator is the credit spread, meaning the extra yield investors demand for holding corporate bonds instead of government debt. The denominator is the equity risk premium, the extra return the stock market is expected to deliver over risk-free rates. Dividing one by the other produces a beta figure that slots into the same valuation models you’d use for equity beta.
The Three Inputs
Cost of Debt
Use the yield to maturity on the company’s outstanding bonds, not the coupon rate. YTM reflects the market’s current assessment of credit risk and the time value of money baked into the bond price. Pull it from bond market data providers or a financial terminal that tracks real-time pricing on publicly traded debt.
Risk-Free Rate
Standard practice is the yield on U.S. Treasury securities, and the key rule is maturity matching. Use a Treasury yield whose duration aligns with the maturity of the corporate debt you’re analyzing. The ten-year Treasury is the most common benchmark for long-term corporate bonds.1FRED | St. Louis Fed. Market Yield on U.S. Treasury Securities at 10-Year Constant Maturity Pairing a two-year Treasury rate with a ten-year corporate bond would bake different inflation expectations and duration risk into the two sides of your equation, producing a meaningless spread.
Equity Risk Premium
The equity risk premium is the additional return investors expect from stocks over risk-free government debt. Two widely referenced 2026 estimates: Kroll (formerly Duff & Phelps) recommends a U.S. equity risk premium of 5.0%, a figure in effect since June 2024.2Kroll. Recommended U.S. Equity Risk Premium and Corresponding Risk-Free Rates Aswath Damodaran’s implied premium for the U.S. market, derived from current stock prices and expected cash flows, sits closer to 4.5–4.7%.3NYU Stern. Country Default Spreads and Risk Premiums Current practitioner estimates generally fall between 4% and 6%. The 5–8% range sometimes quoted in older textbooks reflects historical averages that don’t match the forward-looking figures used in practice today.
Keep the Inputs Consistent
All three inputs must share the same currency and time horizon. A U.S. dollar risk-free rate paired with a market risk premium derived from European equities introduces a mismatch that renders the output meaningless. If you’re valuing a company with euro-denominated debt, every input should be euro-based.
Worked Example
Suppose a company’s ten-year bonds trade at a yield to maturity of 6.5%. The ten-year Treasury yield is 4.3%, and you’re using Kroll’s recommended equity risk premium of 5.0%.
Step 1. Calculate the credit spread. Subtract the risk-free rate from the cost of debt: 6.5% − 4.3% = 2.2%. That 2.2% is the extra compensation bondholders demand for taking on this company’s credit risk instead of lending to the U.S. government.
Step 2. Divide by the equity risk premium. Take the 2.2% spread and divide by 5.0%: 2.2% / 5.0% = 0.44. That’s your debt beta.
A debt beta of 0.44 says this company’s debt carries meaningful systematic risk. Its returns move with the broader market, though at less than half the intensity. This level is typical of bonds rated around BB, the upper end of high-yield territory. If you expected an investment-grade figure, a result this high is a signal to double-check either the company’s credit profile or your input assumptions.
If the same company’s bonds instead traded at a YTM of 5.1%, the math would change significantly: (5.1% − 4.3%) / 5.0% = 0.16. That lower debt beta reflects the reduced credit risk that comes with a narrower spread, consistent with solid investment-grade debt.
Sanity-Check Against Credit Rating Benchmarks
The formula gives you a precise number, but benchmarks tell you whether it’s plausible. Credit ratings are the natural organizing framework because the spread that drives the formula is itself a function of creditworthiness.
- AAA to AA (high-grade). Spreads are thin, and debt betas typically land in the 0.05 to 0.15 range. Bonds at this quality behave more like government debt than like equities; their price movements are driven mostly by interest rate changes rather than by company-specific or market-wide credit cycles.
- A to BBB (investment-grade). As credit quality steps down, spreads widen and debt betas generally sit between 0.15 and 0.35. BBB debt in particular tends to carry enough credit sensitivity that ignoring its beta will meaningfully distort an unlevered beta.
- BB to B (high-yield). Below investment grade, spreads expand sharply and debt betas commonly range from 0.35 to 0.60 or higher. At these levels, the return profile starts to look less like a fixed-income instrument and more like a dampened version of the equity.
- CCC and below (distressed). For companies in serious financial trouble, debt beta can climb toward and even exceed 1.0. Under the Merton framework, as leverage rises toward the point where the firm is funded almost entirely by debt, debt beta converges to the asset beta, and bondholders effectively bear all of the firm’s business risk.4Harvard Business School. Leverage and the Beta Anomaly
Industry matters too, because sectors with stable, regulated cash flows tend to carry lower debt betas than cyclical industries at the same credit rating. A BBB-rated utility and a BBB-rated semiconductor firm should not have identical debt betas, and the utility’s number will typically sit at the low end of the range while the cyclical name pushes toward the high end.
Why the Formula Tends to Overstate
Your calculated debt beta is closer to an upper bound than a precise measurement. Not all of the credit spread compensates for systematic risk. Part of it covers expected default losses and a liquidity premium, neither of which has anything to do with market co-movement. Some practitioners apply a haircut, discounting the formula result by a third or more, to isolate the purely systematic component. If your calculated figure lands at the high end of the benchmark range for the company’s rating, that distinction is worth keeping in mind before you plug the number into anything downstream.
When You Can Safely Assume Zero
Many textbooks and quick models set debt beta to zero. That assumption holds up well enough when a company’s bonds are rated AA or above and credit spreads are narrow, because the resulting debt beta would be so small (under 0.10) that including it barely moves the needle on your unlevered beta.
The assumption breaks down as credit quality declines. For a BBB firm with a debt beta around 0.20 to 0.30, ignoring it will understate the unlevered beta and overstate the levered equity beta you’d calculate when relevering for a target capital structure. For high-yield issuers, the error compounds quickly. A debt beta of 0.40 on a firm with a 50% debt-to-capital ratio means debtholders are absorbing a substantial share of the systematic risk that a zero-debt-beta model dumps entirely on equity.
A practical test: if the credit spread on the company’s debt is less than roughly 75 basis points, the resulting debt beta will be small enough to safely ignore (around 0.15 or below with a 5% ERP). Once spreads push past 150 basis points, compute it. In high-yield territory, skipping the calculation is a shortcut that costs accuracy in exactly the situations where leverage and credit risk are driving the valuation.
Where the Formula Breaks: Distressed Debt
As a company approaches insolvency, the standard credit-spread formula becomes unreliable. Under the Merton structural credit model, risky debt can be viewed as a risk-free bond minus a put option on the firm’s assets. As firm value drops toward the face value of the debt, that embedded put moves deeper into the money and the debt starts behaving more like equity.4Harvard Business School. Leverage and the Beta Anomaly The spread-based formula assumes a stable relationship between credit spreads and systematic risk that deteriorates as default becomes likely, so it can actually understate debt beta at that end of the spectrum.
For distressed companies, the more reliable approach is to look at the actual trading behavior of the bonds. If the bonds are liquid enough, regressing their returns against a broad market index gives you an empirical debt beta that captures the convergence to asset beta directly. When bonds trade at deep discounts to par and their daily price movements track the equity more than the Treasury market, you’re looking at a debt beta that may approach or exceed 1.0.
What to Do With the Number
Debt beta is rarely the endpoint. Most analysts calculate it in order to unlever and relever an equity beta between the observed capital structure and a target one. Two families of formulas dominate that work: Hamada, which assumes debt beta is zero, and Harris-Pringle (and Damodaran’s debt-adjusted variant), which use the debt beta you just calculated.5IESE Business School. Levered and Unlevered Beta6NYU Stern. Relative Risk Measures Using a non-zero debt beta pulls the unlevered beta up and the relevered equity beta down, because it recognizes that some of the market risk Hamada assigns entirely to equity is actually being borne by debtholders. For a firm with meaningful credit risk, the gap between the two approaches flows straight through into the cost of capital and the final valuation.