Price-to-Book Ratio (P/B)

What it is

The price-to-book ratio divides a company's market capitalisation by its book value (net assets — total assets minus total liabilities). A P/B of 1.0x means the market values the company at exactly what its balance sheet says it's worth. A P/B of 3.0x means the market is paying three pounds for every pound of net assets.

It was Benjamin Graham's primary valuation tool in the 1930s and 1940s, when many listed companies traded below net asset value and investors could, in theory, buy a company for less than its liquidation value.

How to calculate it

Or on a per-share basis: P/B = Share Price ÷ Net Asset Value Per Share

Book value is shareholders' equity on the balance sheet: total assets minus all liabilities. This includes both tangible assets (property, equipment, inventory) and intangible assets (goodwill, patents, brands), unless you choose to strip out intangibles — a stricter variant called Price/Tangible Book.

Where P/B is most useful

For most modern businesses, P/B is not a particularly meaningful primary metric. A software company may have minimal physical assets, generate enormous free cash flow, and trade at 20x book value — and be entirely fairly valued. Penalising it for a high P/B misses the point entirely.

But there are sectors where P/B is indispensable:

Banks: The balance sheet is the product for a bank. Return on equity (profit as a percentage of book value) is the primary profit measure. A bank trading at 0.8x book is valued below its asset value — which may indicate concerns about the quality of its loan book, or it may represent genuine undervaluation. Historically, quality UK banks (Lloyds, NatWest) have traded between 0.7–1.2x book during normal conditions.

Insurers: Similarly balance-sheet-centric. Embedded value — a proprietary measure of the net present value of future insurance profits — is often used alongside or instead of book value.

Mining and natural resources: Asset value matters when physical resources underpin the business. Though here, commodity prices create such volatility in asset values that P/B is less reliable as a standalone metric.

Asset management: Tracking book value on investment portfolios matters.

The intangibles problem

Modern accounting creates a structural bias: internally generated brand value, customer relationships, and intellectual property are not on the balance sheet. A company that spent twenty years building the Diageo brand did not capitalise that investment as an asset — it was expensed through the P&L year by year.

This means the book values of consumer brands and technology companies are systematically understated. Their high P/B ratios partly reflect this accounting reality, not pure overvaluation. Price/tangible book strips out acquired goodwill but doesn't resolve the underlying problem.

Low P/B as a value signal

Stocks trading below book value are sometimes called deep value situations. Graham built his career on them. The logic: if a business is trading at, say, 0.6x book, you could theoretically buy it, liquidate the assets, pay off the liabilities, and receive more than you paid.

In practice, this works when:

• The asset values are realistic (marked to market, not inflated accounting values)
• The business isn't continuing to erode those assets through ongoing losses
• There's a catalyst: management change, activist investor, strategic review, takeover

Without a catalyst, value traps abound — companies that look cheap on P/B because the market is correctly pricing in ongoing deterioration.

Not financial advice. P/B should be considered alongside earnings quality, ROE, and sector context.