What price-to-book actually compares
Book value per share is the accounting net worth attributable to one common share: everything the company owns, less everything it owes, less any claim that ranks ahead of common stock. Price-to-book puts the market's number over the accountant's number. A P/B of 2.0 says investors will pay two dollars for each dollar of net assets on the books.
The multiple is at its most useful where the book number is close to a real number. A bank's balance sheet is mostly loans and securities carried at amortised cost or fair value, and its equity is a regulated, audited quantity that the market genuinely trades around. At the other extreme, a software company's most valuable assets — its code, its customer relationships, its brand — were expensed as they were created and appear nowhere on the balance sheet, so its book value is close to meaningless and its P/B will be high for reasons that have nothing to do with being expensive.
That is the discipline the multiple demands: P/B compares price against an accounting convention, and you have to know how well that convention describes the business before the ratio means anything.
Building book value per share correctly
Start with total shareholders' equity. Subtract preferred stock at its carrying value, because preferred shareholders have a claim that ranks ahead of common and their capital is not yours. What remains is common equity. Divide by diluted shares outstanding and you have book value per share.
Use period-end diluted shares, not the weighted average from the EPS note. Book value is a stock measured at a point in time, so pairing it with an average share count over a period mixes two different dates. The distinction matters most for companies that have been buying back stock heavily, which is exactly the population where P/B gets quoted.
Tangible book value goes one step further and removes goodwill and acquired intangibles. Goodwill is the premium paid over the fair value of net assets in an acquisition; under US GAAP it is not amortised but is tested for impairment, so it can sit unchanged on a balance sheet for a decade and then vanish in one charge. Removing it answers a different question: what is the net worth of the assets that would still be there if the acquisitions had never happened? Bank analysts almost always work in tangible terms for this reason, and regulatory capital is defined that way too.
The theoretically grounded version of the multiple links it back to profitability: justified P/B = (ROE − g) ÷ (r − g), where r is the cost of equity and g the sustainable growth rate. Read that identity carefully and it says the whole thing. A company earning exactly its cost of equity is worth exactly book value, whatever its growth rate, because setting ROE = r makes the numerator and denominator equal. A company earning more than its cost of equity is worth a premium; one earning less is worth a discount. P/B is really a statement about return on equity wearing a valuation costume.
Worked example: a $12bn-equity company at $68 a share
The defaults describe a mid-sized financial group, all dollar figures in millions: total shareholders' equity $12,000, preferred stock $500, goodwill and intangibles $2,800, 420 million diluted shares and a share price of $68.
- Common equity. 12,000 − 500 = $11,500M.
- Book value per share. 11,500 ÷ 420 = $27.3810.
- Tangible common equity. 11,500 − 2,800 = $8,700M.
- Tangible book value per share. 8,700 ÷ 420 = $20.7143.
- P/B. 68 ÷ 27.3810 = 2.4835×.
- P/TBV. 68 ÷ 20.7143 = 3.2828×.
- Market capitalisation and premium. 68 × 420 = $28,560M of market value against $11,500M of common equity, a premium of $17,060M.
The gap between 2.48× and 3.28× is entirely the goodwill. Goodwill is 2,800 ÷ 11,500 = 24.3% of common equity, and removing it raises the multiple by 3.2828 ÷ 2.4835 − 1 = 32.2% — which is 1 ÷ (1 − 0.243) − 1, the arithmetic of shrinking a denominator. Whenever someone quotes a bank on "1.4× book", ask which book they mean, because the two figures for the same company can differ by a third.
How to read the multiple
Compare P/B against ROE, not against other companies' P/B. The justified-P/B identity says the two move together. A company on 2.5× book earning a 20% ROE against a 10% cost of equity is not obviously expensive; a company on 1.2× book earning 6% against the same cost of equity is not obviously cheap. Plotting a peer group's P/B against its ROE and looking for the outliers is far more informative than ranking on P/B alone.
Below 1.0× means the market disagrees with the balance sheet, the returns, or both. It can be an opportunity, and it is more often a signal that assets are carried above what they will realise or that ROE will stay below the cost of equity. Take the discount as a question rather than an answer, and look at the composition of assets before concluding anything.
Very high multiples usually indicate the balance sheet is not where the value is. For a company whose competitive advantage is intangible and internally generated, a P/B of 15× tells you almost nothing except that the accounting model does not fit. Use an earnings or cash-flow multiple such as the PEG ratio instead.
Watch buybacks. Repurchasing stock above book value reduces book value per share, which mechanically raises P/B without any change in the business. A steadily rising P/B at a company with a large buyback programme may be arithmetic, not re-rating.
Justified price-to-book from ROE and cost of equity
| Return on equity | r = 8% | r = 9% | r = 10% | r = 11% | r = 12% |
|---|---|---|---|---|---|
| 6% | 0.60 | 0.50 | 0.43 | 0.38 | 0.33 |
| 8% | 1.00 | 0.83 | 0.71 | 0.63 | 0.56 |
| 10% | 1.40 | 1.17 | 1.00 | 0.88 | 0.78 |
| 12% | 1.80 | 1.50 | 1.29 | 1.13 | 1.00 |
| 15% | 2.40 | 2.00 | 1.71 | 1.50 | 1.33 |
| 20% | 3.40 | 2.83 | 2.43 | 2.13 | 1.89 |
The diagonal where ROE equals r is exactly 1.00 in every column: a company earning precisely its cost of equity is worth precisely its book value, and growth changes nothing about that.
Mistakes that break a P/B comparison
- Leaving preferred stock in the numerator of book value. Preferred capital does not belong to common shareholders. Including it overstates BVPS and understates P/B.
- Using weighted average shares. Book value is a point-in-time figure and needs a point-in-time share count. The weighted average belongs in EPS, not here.
- Comparing a goodwill-heavy company with an organically grown one on stated book. The acquirer's equity includes purchase premium the organic grower never had to record. Compare on tangible book or not at all.
- Forgetting that accumulated other comprehensive income swings book value. Unrealised losses on securities portfolios can move a bank's equity sharply without any change in earnings.
- Reading a sub-1.0 multiple as automatically cheap. It is a statement that the market expects ROE below the cost of equity, which is frequently correct.
- Applying P/B to a business with no meaningful book value. Software, pharmaceuticals and consumer brands expense the spending that creates their real assets. The ratio is arithmetically fine and economically empty.
Where P/B fits among the other multiples
Price-to-book is the balance-sheet member of a family. The P/E and PEG price the income statement, EV/EBITDA prices the whole enterprise before financing, and price-to-sales prices the top line for companies with no profit yet. P/B is the one that keeps working when earnings are negative, which is why it dominates in banking, insurance, shipping and real estate — sectors where a loss-making year is a cyclical event rather than a failure.
The natural companion measure is return on equity, since the justified-P/B identity makes the two inseparable, and the DuPont decomposition tells you whether that ROE comes from margin, asset turnover or leverage. If it comes mostly from leverage, a high P/B is a thinner cushion than it looks. For the value-creation version of the same question in dollars rather than multiples, see economic value added, which asks whether returns exceed the cost of capital directly instead of inferring it from a price.
One caution about tangible book in particular: it is the right measure for asking what would be left in a wind-up, and the wrong measure for asking what a going concern is worth. An acquisition that genuinely created value produces goodwill, and removing that goodwill does not remove the value it represents. Use both figures and know which question each answers.
Key terms
- Book value
- Total assets less total liabilities, as carried in the financial statements. For common shareholders, less any preferred claim.
- Tangible common equity
- Common equity with goodwill and other intangible assets removed. The base for most bank capital comparisons.
- Justified P/B
- (ROE − g) ÷ (r − g). The multiple a constant-growth company deserves given its return on equity, growth and cost of equity.