P/B Ratio: Finding Undervalued Companies

Concepts

What Is the Price-to-Book Ratio?

The P/B formula:

P/B Ratio = Stock Price / Book Value Per Share

What is book value per share? Take shareholders' equity from the balance sheet (total assets minus total liabilities) and divide by the number of shares outstanding. In simple terms, if the company sold all its assets and paid off all its debts today, book value per share is how much each share would receive.

P/B = 1 means the stock price equals book value. P/B = 2 means the market is pricing the company at twice its book value.

What Does P/B < 1 Mean?

When P/B is below 1, the stock's market price is less than the company's net asset value on the books. In theory, this is a "discount sale" -- sounds like a bargain, but reality is more nuanced:

It could be a genuine bargain if:

• The market is temporarily too pessimistic and undervaluing the company's assets
• The economy is in a trough and the stock has been dragged down with the broader market
• The company is restructuring or transforming, and the market has not yet priced in its future value

It could be a value trap if:

• The quality of the company's assets is questionable (e.g., inventory write-downs, uncollectible receivables)
• The industry is in structural decline and book assets may continue to lose value
• The company is losing money consistently, so book value will only shrink further

So P/B < 1 is not an automatic buy signal -- you still need to evaluate profitability and industry outlook.

Which Industries Is P/B Best Suited For?

P/B is particularly useful for asset-heavy industries where book value is a meaningful measure:

• Banks and financial institutions: Their assets are mostly financial instruments, so book value closely approximates actual value. P/B is one of the most important metrics for valuing bank stocks.
• Construction and real estate: These companies hold significant land and property, making their book values informative.
• Commodities / Steel / Shipping: These are cyclical industries where earnings swing wildly, making P/E unreliable; P/B tends to be more stable.
• Asset-rich companies: Firms holding substantial real estate that is recorded at historical cost on the books -- actual market value may be far higher than stated book value.

Conversely, P/B is less useful for asset-light companies (software, brands, services), because their most valuable assets (technology, brand equity, talent) are not reflected in book value.

P/B Works Even Better Paired with ROE

A practical approach is to look at P/B and ROE together:

• Low P/B + High ROE: Potentially an undervalued quality company -- worth a deeper look
• Low P/B + Low ROE: The stock is cheap for a reason -- the company is not earning well
• High P/B + High ROE: A justifiably high valuation -- the company genuinely earns its premium
• High P/B + Low ROE: Potentially overvalued -- proceed with caution

Hands-On: Using CTSstock

1. Go to /analysis/2330 (using TSMC as an example)
2. Click the Valuation tab at the top
3. Find the P/B valuation model
4. You can see:
   • The current P/B multiple
   • The historical P/B range
   • Fair value estimates based on different P/B assumptions
5. Cross-reference with ROE data on the Financial Ratios tab to judge whether the current P/B is reasonable
6. For bank stocks or cyclical stocks, P/B is often more useful than P/E

FAQ

Q: What P/B level is considered cheap? A: It depends on the industry. For bank stocks, a P/B around 1.0 is considered fair; below 0.8 may be on the low side. For tech stocks, P/B of 3-5 is common due to their asset-light nature. The key is to compare against industry peers and the company's own historical range.

Q: Does book value per share change? A: Yes. Every year a company earns (or loses) money, shareholders' equity changes, and so does book value per share. If a company is consistently profitable and does not pay out all its earnings as dividends, book value per share will grow over time.

Q: Why is TSMC's P/B so high? A: Because TSMC is a classic high-ROE company, and the market is willing to pay a premium for high-quality earnings power. For companies like TSMC, P/E or DCF may be more appropriate valuation methods.