P/B Ratio: Pricing a Company Against Book Equity

Key Takeaways

• P/B equals market price per share divided by book value per share, where book value is shareholders' equity minus preferred stock.
• The fair P/B rises with return on equity and growth, and falls with cost of equity and risk.
• It is most informative for banks, insurers, and asset-heavy industries where book equity is a meaningful number.
• For tech and brand-driven firms, book equity understates economic value and P/B carries little information.

What It Is

The price to book ratio P/B is an equity multiple that scales the market capitalization of common shareholders to the accounting equity attributable to those shareholders. Book value is computed from the balance sheet as total assets minus total liabilities minus preferred equity.

Damodaran groups P/B with book value multiples rather than earnings multiples because its denominator is a stock variable from the balance sheet, not a flow from the income statement. That distinction matters: book value is far less volatile than earnings and is rarely negative outside of distressed firms.

The Intuition

If a company could be liquidated tomorrow and the assets sold at carrying value, common shareholders would receive the book equity per share. The P/B ratio measures how much more, or less, the market expects from continuing operations.

Damodaran derives a closed-form expression where the justified P/B equals (ROE minus growth) divided by (cost of equity minus growth). The corollary is direct: a firm with ROE above its cost of equity should trade above 1.0 P/B, and a firm with ROE below its cost of equity should trade below 1.0. That single relationship explains why high-ROE banks trade at 2 P/B while low-ROE banks trade below 1.

How It Works

The standard formula is:

P/B = Price per Share / Book Value per Share

Where book value per share equals:

Book Value per Share = (Common Equity - Preferred Equity) / Diluted Shares

Two practical adjustments matter. First, large goodwill from past acquisitions can inflate book equity without representing real assets, which is why analysts often switch to tangible book. Second, share buybacks executed above book value reduce book equity faster than they reduce share count, mechanically raising P/B even when nothing else changes.

The CFA Institute notes that P/B is most useful when book value is a faithful proxy for asset value. That holds best for financial institutions, where assets and liabilities are largely marked at fair value, and least for technology, pharma, and consumer brand companies, where the most valuable assets are off-balance-sheet.

Worked Example

A regional bank reports common equity of $4.8 billion with 120 million diluted shares outstanding. Book value per share is $40. The stock trades at $60.

P/B = 60 / 40 = 1.5

Suppose the bank earns net income of $480 million, giving ROE of 10%. If the cost of equity is 9% and long-term growth is 3%, the justified P/B from Damodaran's formula is:

Justified P/B = (0.10 - 0.03) / (0.09 - 0.03) = 0.07 / 0.06 = 1.17

The market is paying 1.5 against a justified 1.17, suggesting either higher growth expectations than 3%, lower required return than 9%, or some optimism that has to be examined. Damodaran's sector data shows US bank P/B ratios commonly clustered between 1.0 and 2.0, with high-ROE players above 2 and underperformers below 1.

Common Mistakes

1. Applying P/B to asset-light firms. A software company with $200 million of book equity and a $20 billion market cap will show a P/B of 100. That number contains essentially no valuation information.
2. Ignoring goodwill. Two banks at 1.5 P/B can be very different if one carries 30% of equity in goodwill from acquisitions. Always cross-check with price-to-tangible-book.
3. Forgetting the ROE link. A low P/B with a low ROE is not cheap, it is consistent. Only firms with high ROE and low P/B are statistically the value plays.
4. Comparing across accounting regimes. IFRS and US GAAP treat revaluation of property, intangibles, and pension liabilities differently. Cross-border P/B comparisons need adjustment.
5. Mistaking buyback-driven P/B for organic change. Repurchasing stock above book value shrinks book equity. A rising P/B trend can be entirely due to buyback mechanics rather than improving fundamentals.

Frequently Asked Questions

What is the price to book ratio P/B in simple terms? It is the market price of a share divided by the accounting book value per share. A P/B of 1.5 means the market values the equity at 1.5 times its accounting net worth.

How does the price to book ratio P/B affect investment decisions? For banks and insurers, P/B is a primary valuation benchmark and is interpreted alongside ROE. For most other sectors, a high or low P/B is meaningful only when paired with profitability and growth metrics.

What is a real-world example of the P/B ratio? Damodaran's annual sector dataset shows US banks, REITs, and insurers clustered around 1 to 2 times book, while software and pharma trade at very high P/Bs because book equity captures little of their economic value.

How can investors use the P/B ratio effectively? Always pair P/B with ROE and the cost of equity. A high-ROE firm trading at 1 P/B is statistically a stronger value signal than a low-ROE firm at the same multiple.

How is the P/B ratio different from price-to-tangible-book? P/B uses total book equity, including goodwill and intangibles. Price-to-tangible-book subtracts those items, leaving only hard equity that would survive a balance sheet write-down.

Sources

1. Damodaran, A. Chapter 19: Book Value Multiples. NYU Stern. https://pages.stern.nyu.edu/~adamodar/pdfiles/valn2ed/ch19.pdf
2. Damodaran, A. Price-Book Value Ratio: Definition. NYU Stern. https://pages.stern.nyu.edu/~adamodar/pdfiles/eqnotes/pbv.pdf
3. Damodaran, A. Price and Value to Book Ratio by Sector (US). NYU Stern. https://pages.stern.nyu.edu/~adamodar/New_Home_Page/datafile/pbvdata.html
4. CFA Institute. Market-Based Valuation: Price and Enterprise Value Multiples. https://www.cfainstitute.org/insights/professional-learning/refresher-readings/2026/market-based-valuation-price-enterprise-value-multiples

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.