What Is the P/B Ratio? Valuing Stocks by Book Value
P/B compares a stock's market price with the company's book value. We explain how to calculate it, what high or low P/B means, its limitations, and how to use it alongside P/E to value stocks.
Is the stock expensive or cheap versus real assets?
P/E compares a stock price with earnings. But there is another angle: is the stock expensive or cheap versus the company''s real assets? That is where the P/B ratio comes in.
What P/B is
P/B (Price-to-Book) compares a stock''s market price with the company''s book value:
P/B = Market price per share / Book value per share
Book value is the company''s net assets on the accounting books: total assets minus total liabilities. Loosely, it is the theoretical money left for shareholders if the company sold all assets and paid off all debt.
Example: P/B = 1 means the stock price equals book value exactly. P/B = 3 means the market values the stock at 3x net asset value on the books.
What high or low P/B says
- Low P/B (near 1 or below 1): the stock may be undervalued versus assets — attractive to value investors. But it can also signal the company is in trouble (the market prices it low for a reason).
- High P/B: the market expects the company to create value far beyond book assets — common in growth and tech companies. But a very high P/B can also signal overvaluation.
There is no absolute "right" threshold — it must be judged by industry and context.
An important limitation of P/B
P/B is especially useful for some industries, but less meaningful for others:
- Fits asset-heavy companies (banks, insurance, real estate, manufacturing) — where book value reflects real value well.
- Less fitting for companies driven by intangibles (tech, software, brands) — because their real value lies in things not fully recorded on the books. A great software company can have a very high P/B and still be reasonable.
So do not use P/B alone to conclude a stock is "expensive" or "cheap."
Use P/B with other metrics
P/B is strongest when combined:
- P/B + P/E: P/E looks at earnings, P/B looks at assets — two complementary angles.
- P/B + ROE: a company with high P/B but high ROE may deserve it (good returns on capital). High P/B with low ROE is suspicious.
- Compare within the industry: only compare P/B among companies in the same field.
Conclusion
P/B compares a stock price with net asset value on the books. Low P/B may be cheap or a sign of trouble; high P/B may be growth expectations or overvaluation. It is most useful for asset-heavy companies and should be used with P/E and ROE rather than alone. Understanding P/B lets you view a stock from an asset angle, not just earnings.
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