Value Anomaly
Also written Value effect
The finding that stocks with a high book value-to-price ratio have earned superior risk-adjusted returns — an anomaly against the EMH that underpins value investing.
In plain language
A company's book value is public. So is its share price. The efficient market hypothesis says comparing the two should not help anyone beat normal returns. Research says it did.
The workbook reports a positive link between the book value to price ratio and future stock returns. Many studies found that stocks with a high book-to-price ratio earned better returns, even after allowing for risk.
The book-to-price ratio is public information anyone can get. So that link goes against the efficient market hypothesis.
The workbook adds that this anomaly is at the heart of why value investing is so popular.
How it works
The source the workbook cites (Chapter 13, section 13.4.3): Rosenberg, Reid and Lanstein (1985), Persuasive Evidence of Market Inefficiency, The Journal of Portfolio Management.
Reading the ratio. A high book-to-price ratio is the same as a low price-to-book ratio. The stock is cheap relative to its accounting net worth.
Which form of the EMH it challenges. The semi-strong form says prices fully reflect all public information, explicitly including price-book value (P/BV) ratios. A reliable return premium from P/BV therefore contradicts semi-strong efficiency.
How it shows up in portfolio strategy:
| Where | What the workbook says |
|---|---|
| Value investment style (Chapter 18, section 18.8.2) | Buy stocks undervalued relative to intrinsic value; screens include low P/E, low PEG, low price-to-book, low P/S, low price-to-cash-flow, high dividend yield, low debt-equity |
| Smart beta factors (section 18.5) | Value measured by P/E, P/B, P/S and dividend yield |
| Fusion investing (Chapter 14, section 14.4) | Step I screens for value using P/E, P/BV, P/S |
The caution. Managers must watch for a value trap — mispricing may be illusory and the company genuinely worse than the analyst thinks (section 18.8.2).
A worked example
Illustrative figures. Two listed engineering companies, both with ₹200 book value per share.
| Company P | Company Q | |
|---|---|---|
| Share price | ₹160 | ₹600 |
| Book-to-price (B/P) | 200 ÷ 160 = 1.25 | 200 ÷ 600 = 0.33 |
| Price-to-book (P/B) | 160 ÷ 200 = 0.80 | 600 ÷ 200 = 3.00 |
Company P is the high book-to-price (value) stock. The value anomaly says that, across many such stocks and periods, portfolios of P-type stocks earned superior risk-adjusted returns compared with Q-type stocks.
A value manager building a ₹20 crore portfolio might screen the universe for P/B below 1, then analyse each survivor for a value trap. Suppose P trades at 0.8 times book because its order book has collapsed and losses will erode book value over the next two years. Then the "cheap" ratio is misleading — the anomaly describes an average across stocks, not a guarantee for any single one.
Why NISM asks about it
Chapter 13 (Concept of Informational Efficiency), section 13.4.3, presents the value anomaly as evidence against the EMH and the basis of value investing. Chapter 18 (Equity Portfolio Management Strategies) turns it into practice through the value investment style, value screens and value as a smart beta factor. Questions test the direction of the relationship and why it contradicts market efficiency.
Common exam traps
- High book-to-price = low price-to-book. The anomaly favours high B/P stocks. A question worded in P/B terms flips the direction.
- Risk-adjusted returns, not just higher raw returns.
- It contradicts the semi-strong form, because P/BV is public information the semi-strong form says is already in prices.
- Value anomaly ≠ size anomaly. Size is about market value; value is about book-to-price.
- Value trap: a low P/B is not proof of undervaluation. The workbook warns mispricing may be illusory.
Where this is taught
Free preparation for NISM Series XXI-BRelated terms
- Price to Book ValueShare price divided by book value per share — how many times the accounting net worth of a company the market is willing to pay.
- Fusion investingA strategy that combines fundamental analysis with behavioural finance: screen for value, filter for financial strength, then pick the stocks showing strong price momentum.
- Market anomalyA pattern of returns that departs from what an asset's fundamentals and risk — as measured by CAPM or another pricing model — say it should earn, and so contradicts market efficiency.
- Semi-strong-form EfficiencyThe hypothesis that prices reflect all historical and publicly available information and adjust rapidly to news — so neither technical nor fundamental analysis earns above-average risk-adjusted returns.
- Size AnomalyThe finding that small firms, measured by total market value, have consistently earned larger risk-adjusted returns than large firms — contradicting market efficiency.
- Growth investingA common private equity strategy of taking a minority stake to help a company grow further — typically at the intersection of VC and PE, where the company is still growing but may already be profitable.
- Piotroski scoreA discrete score from 0 to 9, built from nine criteria on a company's financial statements, used to filter for financially strong value stocks — nine is the best score, zero the worst.
- January effectA market anomaly in the US: year-end tax selling pushes prices down in late November and December, and the buying back in early January pushes them up — a pattern inconsistent with market efficiency.