Altman Z-Score: Predicting Bankruptcy Before It Happens

Key Takeaways

• The Altman Z-Score combines five ratios covering liquidity, retained earnings, operating profitability, market solvency, and asset turnover into one bankruptcy-prediction number.
• Altman's original 1968 model correctly classified about 95% of firms one year before bankruptcy and 72% two years out, making it one of the most validated simple credit-screening tools.
• The public-company Z-Score uses market value of equity; applying it to private firms requires the recalibrated Z' variant, which substitutes book equity instead.
• Asset-light software and media companies often show low Z-Scores not because of distress but because accounting conventions understate their true asset base.

What It Is

Edward I. Altman, then an assistant professor at NYU Stern, published the model in 1968 in the Journal of Finance under the title "Financial Ratios, Discriminant Analysis and the Prediction of Corporate Bankruptcy." He applied multiple discriminant analysis to a matched sample of 33 bankrupt and 33 solvent US public manufacturing firms and selected five ratios that, weighted together, best separated the two groups.

The output is a single score. Altman reported the original model correctly classified roughly 72 percent of firms two years before bankruptcy and about 95 percent one year before. The score has since become a staple in credit analysis, distressed-debt research, and audit going-concern reviews.

The Intuition

Any one ratio can lie. A firm with high leverage might still be safe if it generates strong operating earnings. A firm with rising sales might still be sliding into insolvency if retained earnings are deeply negative. Altman's insight was to use discriminant analysis to find a weighted combination of ratios that, taken together, do a better job of classifying firms than any single ratio does alone.

The five ratios span four dimensions of corporate health: liquidity, accumulated profitability, current earning power, market-based solvency, and asset productivity. A firm has to look weak on several fronts at once to produce a low Z.

How It Works

The original 1968 model for public manufacturing firms is:

Z = 1.2*A + 1.4*B + 3.3*C + 0.6*D + 1.0*E

Where:

A = Working Capital / Total Assets
B = Retained Earnings / Total Assets
C = EBIT / Total Assets
D = Market Value of Equity / Book Value of Total Liabilities
E = Sales / Total Assets

Altman proposed three zones for the public manufacturing Z:

• Safe zone: Z greater than 2.99
• Grey zone: 1.81 to 2.99
• Distress zone: Z below 1.81

Two widely used variants exist. The Z' model replaces the market value of equity in ratio D with book value of equity and is intended for private manufacturing firms, with recalibrated coefficients. The Z'' model drops the asset-turnover ratio E entirely and re-weights the remaining four ratios, making it suitable for non-manufacturing and emerging-market firms where sales-to-assets is not comparable across industries.

Worked Example

Consider a mid-cap US industrial firm with the following figures (in millions):

• Total assets: 5,000
• Working capital: 500
• Retained earnings: 1,200
• EBIT: 450
• Market cap: 2,000
• Total liabilities: 3,000
• Sales: 4,500

Compute each ratio:

A = 500 / 5000    = 0.10
B = 1200 / 5000   = 0.24
C = 450 / 5000    = 0.09
D = 2000 / 3000   = 0.67
E = 4500 / 5000   = 0.90

Apply the weights:

Z = 1.2*0.10 + 1.4*0.24 + 3.3*0.09 + 0.6*0.67 + 1.0*0.90
Z = 0.12 + 0.336 + 0.297 + 0.402 + 0.90
Z = 2.055

A Z of 2.06 sits in the grey zone. It is not an immediate red flag, but it is also not reassuring. A credit analyst would track Z over several quarters, looking for a trend toward or away from the 1.81 distress threshold.

Common Mistakes

1. Applying the public Z to private firms. Ratio D uses market value of equity, which private firms do not have. Using book value with the 0.6 weight from the public model is a category error. Use the Z' variant, which was recalibrated on private-firm data.

2. Scoring banks, insurers, and other financials. The Z-Score assumes a standard industrial balance sheet. Financial firms have fundamentally different asset and liability structures, so the ratios and coefficients do not transfer. Altman himself cautioned against this use.

3. Ignoring that Z relies on book values. Ratios A, B, and C all use total assets in the denominator and exclude intangibles that never hit the balance sheet. Modern asset-light firms in software, media, and professional services often show low Z-Scores that reflect accounting conventions more than distress risk.

4. Using a single-date reading instead of a trend. A Z of 2.2 is more informative when you know it was 3.1 a year ago. Credit analysts watch direction and rate of change. A stable grey-zone firm is different from one whose Z is compressing quarter over quarter.

5. Treating Z as a standalone signal. Z ignores the current cash balance, committed credit lines, debt maturity schedule, and covenant structure. A firm with an ugly Z but 18 months of cash and no near-term maturities is a different risk than the same Z with a wall of debt coming due.

Frequently Asked Questions

Q: What is the Altman Z-Score in simple terms? The Altman Z-Score is a formula that combines five financial ratios into a single number to estimate bankruptcy risk. A score above 2.99 is in the safe zone; below 1.81 is in the distress zone; between the two is a grey zone worth watching.

Q: How does the Altman Z-Score affect investment decisions? A low or falling Z-Score can flag financial stress before it shows up in the stock price or credit spreads. Distressed-debt investors use it to screen for potential opportunities; equity investors use it to avoid companies where bankruptcy risk is rising.

Q: What is a real-world example of the Altman Z-Score? A mid-cap industrial with $500 million working capital, $1.2 billion retained earnings, $450 million EBIT, $2 billion market cap, and $4.5 billion sales on a $5 billion asset base scores a Z of approximately 2.06, in the grey zone, worth monitoring for deterioration.

Q: How can investors use the Altman Z-Score practically? Track the trend over several quarters rather than relying on a single reading. A Z that is falling steadily toward 1.81, even from the safe zone, is more concerning than a stable reading in the grey zone. Also note whether any deterioration comes from the leverage ratio or the profitability ratios.

Q: How is the Altman Z-Score different from the Piotroski F-Score? The Z-Score is primarily a bankruptcy-prediction model designed to identify distress risk. The Piotroski F-Score is a quality-screening tool designed to separate fundamentally improving firms from deteriorating ones within a universe of value stocks. They answer different questions and are often used together.

Sources

1. Altman, E.I. (1968). "Financial Ratios, Discriminant Analysis and the Prediction of Corporate Bankruptcy." Journal of Finance, 23(4), 589-609. Hosted at NYU Stern: https://pages.stern.nyu.edu/~ealtman/Zscores.pdf
2. CFA Institute Enterprising Investor. "The Altman Z-Score in Edward Altman's Own Words." https://blogs.cfainstitute.org/investor/2016/02/02/the-altman-z-score-in-edward-altmans-own-words/
3. Corporate Finance Institute. "Altman's Z-Score Model: Overview, Formula, Interpretation." https://corporatefinanceinstitute.com/resources/commercial-lending/altmans-z-score-model/
4. AccountingTools. "Altman Z Score Formula." https://www.accountingtools.com/articles/the-altman-z-score-formula.html
5. Brattle Group. "Solvency Shortcuts: The Use and Misuse of Simple Tools for Predicting Financial Distress." https://www.brattle.com/wp-content/uploads/2022/05/Solvency-Shortcuts-The-Use-and-Misuse-of-Simple-Tools-for-Predicting-Financial-Distress.pdf

Disclaimer

This article is educational content only and is not financial advice. Nothing here is a recommendation to buy, sell, or hold any security. Consult a licensed advisor before making investment decisions.