Every other valuation guide on this site eventually says the same thing about banks: "use price-to-book instead." This is the article that explains why. The P/B ratio compares a company's market price to the net worth on its balance sheet — and for most companies it is a blunt, secondary tool, but for banks and financials it is the primary lens. This guide explains what book value really is, why it is the right measure for a lender, how return on equity justifies the multiple, and the two ways book value quietly lies.
What book value actually is
Start with the denominator, because it is where the whole ratio lives or dies. Book value is the net worth of a company as its own accounts record it:
\[\text{Book Value} = \text{Total Assets} - \text{Total Liabilities}\]
It is the shareholders' equity — everything the company owns, minus everything it owes. Divide by the number of shares and you get book value per share, the accounting net worth backing each share you buy. The price-to-book ratio then simply compares the market price to that figure:
\[\text{P/B} = \frac{\text{Share Price}}{\text{Book Value Per Share}} = \frac{\text{Market Cap}}{\text{Shareholders' Equity}}\]
A P/B of 1 means you are paying exactly the accounting net worth. A P/B of 3 means the market values the business at three times its balance-sheet worth — it believes the company can generate far more value from that equity than the equity itself suggests. A P/B below 1 means the market is pricing the company below its stated net worth, which is either an opportunity or a warning that the net worth is not real.
The critical question — the one that decides whether P/B is useful at all for a given company — is this: does book value actually mean anything for this business?
Why P/B works for banks and not for FMCG
For most companies, book value badly understates what the business is worth. Consider a consumer-goods company. Its most valuable assets — its brands, its distribution network, the trust built over decades — appear almost nowhere on the balance sheet, because accounting rules do not let a company record a brand it built itself. So its book value is tiny relative to its true worth, and its P/B is enormous and nearly meaningless. The same is true of an IT services firm, whose value is its people and client relationships, or any high-return, asset-light business.
A bank is the opposite. A bank's business is its balance sheet. It takes in deposits and borrowings (liabilities), lends them out and holds securities (assets), and earns the spread. Its equity is not a rough approximation of its worth — it is the direct, working engine of its profits. When a bank's assets and liabilities are financial instruments carried close to their real value, book value is a genuine, meaningful number. That is why:
For a bank, book value is real and P/E is noisy. For a consumer company, book value is meaningless and P/E is the better guide.
The P/E ratio is especially unreliable for banks because their reported profit swings on loan-loss provisions — the money set aside for loans that may go bad. A bank can have a great year for provisions and a terrible one, moving net profit sharply, without the underlying franchise changing at all. Book value and P/B are far steadier, which is why lenders are the one large sector where the market reaches for P/B first and P/E second.
The number that justifies the multiple: return on equity
P/B never travels alone. Its inseparable companion is return on equity (ROE) — the profit a company earns on each rupee of book value:
\[\text{ROE} = \frac{\text{Net Profit}}{\text{Shareholders' Equity}}\]
Here is why they belong together. P/B tells you what you pay for a rupee of equity; ROE tells you what that rupee of equity earns. A bank earning 18% on its equity is producing twice as much profit per rupee of book value as one earning 9% — so it rationally deserves a much higher P/B. The two ratios are the price and the productivity of the same thing.
There is a clean way to see the link. In steady state, a fair P/B is roughly the return on equity divided by the return investors require (the cost of equity):
\[\text{Fair P/B} \approx \frac{\text{ROE}}{\text{Cost of Equity}}\]
If a bank earns a 16% ROE and investors demand 12%, a fair P/B is about 1.3. If a stronger bank earns 20% on the same 12% cost of equity, a fair P/B is about 1.7. And the corollary is the important part: a company earning an ROE below its cost of equity deserves a P/B below 1 — because each rupee of capital it holds produces less than investors could earn elsewhere, so the market correctly values it at less than its book. This is the single most useful idea in the whole ratio.
| ROE vs cost of equity | Justified P/B | Meaning |
|---|---|---|
| ROE well above cost of equity | Well above 1 | Equity is highly productive — pay a premium |
| ROE roughly equals cost of equity | Around 1 | Fairly valued at book |
| ROE below cost of equity | Below 1 | Capital is being destroyed — discount to book |
A worked example
Two banks, each with ₹40,000 crore of shareholders' equity (book value):
| Bank A | Bank B | |
|---|---|---|
| Net profit | 7,200 | 3,200 |
| Shareholders' equity | 40,000 | 40,000 |
| Return on equity | 18.0% | 8.0% |
| Market cap | 1,00,000 | 32,000 |
| Price-to-book | 2.5 | 0.8 |
Bank A trades at 2.5 times book, Bank B at 0.8 times — below its net worth. A beginner sees Bank B as "cheaper." But look at the ROE. Bank A earns 18% on its equity; Bank B earns 8%. If investors require, say, 12%, then Bank A's equity is highly productive and worth a large premium to book, while Bank B is earning less than the cost of the capital it holds — so the market correctly values it below book. The "expensive" bank is the better business, and quite possibly the better value; the "cheap" one is cheap because its capital is working too hard for too little. P/B without ROE is half a sentence.
Where book value lies
Book value is an accounting figure, and accounting figures are opinions dressed as facts. The P/B ratio is only as trustworthy as the book value underneath it, and that number misleads in two directions.
It understates asset-light businesses. As we saw, brands, patents, software and people barely register on a balance sheet, so genuinely valuable companies can show sky-high P/B ratios that mean nothing. Judging an FMCG or IT company on P/B is a category error — reach for P/E, EV/EBITDA or a cash-flow model instead.
It overstates troubled ones. Book value can also be too high. Watch for:
- Bad loans not yet written down. A bank's book value assumes its loans will be repaid. If a chunk will not be, the true equity is lower than stated — which is exactly why a bank sitting on hidden bad loans trades below book. The market is pricing the write-down that the accounts have not yet taken.
- Goodwill from overpriced acquisitions. When a company overpays for an acquisition, the premium sits on the balance sheet as goodwill, inflating book value until it is eventually written off.
- Stale inventory and obsolete assets. Carried at cost, worth far less in reality.
A very low P/B is usually not a bargain — it is the market saying it does not believe the book value is real. Before buying below book, prove the book value is honest.
This is the value trap in its purest form. A P/B of 0.5 looks like buying a rupee for fifty paise — but only if that rupee is actually there.
How P/B fits with the other tools
The price-to-book ratio is not a rival to the multiples you already know — it is the specialist that takes over exactly where they fail:
| Business type | Primary lens | Why |
|---|---|---|
| Banks, NBFCs, insurers | P/B + ROE | Balance sheet is the business; profit is provision-noisy |
| Asset-heavy industrials | EV/EBITDA, EV/EBIT | Capital structure and depreciation matter most |
| Consumer, IT, pharma | P/E, free cash flow | Value is intangible; book value understates it |
| Any business, done properly | DCF / intrinsic value | Values future cash directly, whatever the sector |
The art of using multiples well is knowing which one the business calls for — and for a lender, that answer is almost always price-to-book, read side by side with the return on equity that justifies it.
The bottom line
The price-to-book ratio measures what you pay for a company's accounting net worth — and it earns its keep in one place above all: valuing banks and financials, where the balance sheet genuinely is the business. Used well, it is never read alone. Pair it with return on equity to see whether the equity is productive, and interrogate the book value itself before trusting a low ratio, because a P/B below 1 is far more often a warning than a gift.
FairStocks reads book value, return on equity and the P/B ratio for every listed Indian company straight from its filed accounts — and for banks and financials it applies the lens the business actually calls for, so the valuation reflects how productively the equity is working, not just how the reported profit happened to land this year.