Price-to-book is a older valuation metric that matters far more for some sectors than others — knowing when it's useful versus mostly irrelevant is the skill.
The Formula and Best Use Case
P/B ratio = share price ÷ book value per share, where book value is total assets minus total liabilities (shareholders' equity). A P/B below 1.0 means the market is real-time pricing the company below its accounting net asset value — sometimes a genuine bargain, sometimes a signal the market expects further asset write-downs. P/B is most meaningful for asset-heavy sectors — banks, insurers, real estate — where book value closely tracks tangible worth; it's far less meaningful for asset-light sectors like software, where a company's value comes from intangibles book value doesn't capture.
One thing worth checking: Before using P/B on any company, check its sector first — applying it to a software or services company produces a distorted picture, since most of that company's actual value (brand, intellectual property, customer relationships) sits entirely outside the book value calculation.
Someone Evaluating a Bank or Insurance Stock: P/B is a useful tool here — these sectors' value tracks closely with tangible book assets.
Someone Evaluating a Software or Services Company: P/B is largely uninformative here — favor P/E or free cash flow-based metrics instead for a meaningful valuation read.
Use P/B the Way
- Confirm the company is in an asset-heavy sector before relying on P/B.
- Investigate why a sub-1.0 P/B exists rather than assuming it's automatically a bargain.
- Pair P/B with P/E for a fuller valuation picture.
See the P/E ratio explained for the complementary earnings-based measure.
