Value Factor Strategy
Buy undervalued stocks with high book-to-market ratios. One of the most documented anomalies in finance, backed by 40+ years of academic research.
Overview
The value effect is one of the most studied anomalies in finance. Stocks trading at low prices relative to their book value (high B/M) tend to outperform stocks trading at high prices relative to book value (low B/M).
In plain terms: cheap stocks outperform expensive stocks over time. High B/M stocks are often out-of-favor companies facing temporary challenges. Low B/M stocks are market darlings with optimistic expectations priced in.
The value premium arises because markets systematically overpay for growth and underpay for distress. Investors extrapolate recent performance too far into the future, creating opportunities for patient contrarians.
Key Insight
Value vs Growth: The Core Concept
Stocks are sorted by book-to-market ratio. High B/M stocks (value) trade near or below book value. Low B/M stocks (growth) trade at large premiums to book value.
Trading below book value. Out-of-favor, potentially undervalued.
Trading at 5x book value. Market favorite, high expectations priced in.
Research
Eight landmark papers spanning four decades of value investing research.
The Mathematics
In Plain English
The math behind this strategy is straightforward. Here's what you're actually doing:
- 1Get book value from financial statements. This is total assets minus total liabilities — what shareholders would receive in liquidation.
- 2Compare to market value. Divide book value by market cap. A ratio of 0.8 means book value is 80% of market value.
- 3Rank all stocks by this ratio. High ratios mean cheap stocks. Low ratios mean expensive stocks.
- 4Buy high-ratio stocks (value) and avoid or short low-ratio stocks (growth).
That's it. The formulas below just express this process precisely.
1Book-to-Market Ratio
Book_Value = Total Assets - Total Liabilities; Market_Cap = Price x Shares
2Example Calculation
Company XYZ: Book Value $200M (assets $500M - liabilities $300M), Market Cap $400M (50M shares x $8). B/M of 0.50 means market values at 2x book value — a growth stock.
3HML Factor (Fama-French)
High-Minus-Low: return spread between value and growth. Positive HML = value wins.
Strategy Rules
Entry Rules
- 1Calculate B/M for all stocks using most recent annual data
- 2Remove stocks with negative book value
- 3Rank all stocks by B/M (highest to lowest)
- 4Buy top quintile (20%) — value portfolio
- 5Optional: Short bottom quintile — growth portfolio
Exit Rules
- 1Rebalance annually (June, after fiscal year-end data)
- 2Sell stocks that drop out of top quintile
- 3Sell if book value turns negative (distress)
- 4Cover shorts that rise into top quintile
Position Sizing
- Equal-weight: Same allocation per stock
- Portfolio size: 20-50 stocks
- Max position: 5% per stock
- Sector cap: 25-30% max
Rebalancing
- Frequency: Annual (or semi-annual)
- Timing: June/July (after annual reports)
- Turnover: ~20-30% annually
- Buffer: 5% threshold to reduce trades
Implementation Guide
Implementing a value strategy is straightforward and requires no programming. The key is finding reliable fundamental data and maintaining discipline to hold out-of-favor stocks.
Choose Your Stock Universe
Start with a well-defined group of stocks to screen. The S&P 500 is a good starting point — these are established companies with reliable financial data. You can expand to the Russell 1000 (large and mid-cap) or even the full market, but more stocks means more research. Value works best with profitable companies, so avoid penny stocks and highly speculative names.
- S&P 500 is easiest to start — 500 large-cap companies with clean financial data
- Exclude financial stocks (banks, insurers) since their book values work differently
- Remove stocks with negative book value — these are distressed and risky
- Consider industry-specific universes (e.g., industrials only) for concentrated bets
Set Up Your Screener
Use a free stock screener to filter by book-to-market ratio (or the inverse, price-to-book). Most screeners have this metric built in. You want stocks where market price is low relative to book value — these are trading below what the company would be worth in liquidation. Look for P/B ratios below 1.5, or B/M ratios above 0.67.
- Free screeners: Finviz, Yahoo Finance, TradingView all have P/B filters
- Set minimum market cap ($1B+) to avoid tiny illiquid stocks
- Consider composite screening: combine P/B with P/E and P/S for stronger signals
- Check the "last updated" date — you want recent annual report data
Calculate and Rank
Export your screened stocks to a spreadsheet. Calculate the book-to-market ratio for each: Book Value ÷ Market Cap. Sort from highest to lowest. The top 20% are your "value" stocks. These are companies the market has written off, trading cheap relative to their assets.
- Book value = Total Assets − Total Liabilities (from balance sheet)
- Use trailing 12-month data for consistency across stocks
- Watch for one-time writedowns that artificially boost B/M — check for abnormal values
- A B/M above 1.0 means the stock trades below book value — often a value trap signal
Be skeptical of extremely high B/M ratios (above 2.0). These often indicate severe distress, pending delisting, or accounting issues rather than genuine value.
Select Your Portfolio
Pick 20-30 stocks from your top-ranked list. Equal-weight them — each stock gets the same dollar amount. This diversification protects against any single value trap blowing up your returns. With 20 stocks, each position is 5% of your portfolio.
- Start with top 20-30 ranked stocks for adequate diversification
- Cap any single sector at 25-30% to avoid concentration risk
- Consider quality filters: positive earnings, low debt, stable margins
- Look up each company briefly — avoid obvious value traps (declining industries, fraud risk)
Execute Your Trades
Once a year (typically in June after annual reports are filed), buy your value portfolio. Use limit orders slightly above the current price to ensure execution. Value stocks are often low-volume, so market orders can result in bad fills.
- June/July timing aligns with fiscal year-end data availability
- Place limit orders 0.5-1% above current price for reliable fills
- Spread purchases over 2-3 days if buying more than $100K
- Document your purchase prices and rationale for future review
Rebalance Annually
Value investing requires patience — one year is the minimum holding period. At each annual rebalance, re-run your screens and compare to your current holdings. Sell stocks that have appreciated out of value territory, and buy new value stocks that have emerged. Expect 20-30% turnover.
- Stick to annual rebalancing — more frequent trading adds costs without adding returns
- Use a 5% buffer rule: only trade if a stock clearly moves out of the top quintile
- Reinvest dividends (value stocks often pay higher yields)
- Track your performance vs. a value ETF benchmark like VTV or VLUE
Value can underperform growth for years at a time. From 2007-2020, value trailed growth by over 50%. Stick with your strategy through drawdowns — the premium has always eventually returned.
Data Sources for Fundamental Screening
Free screeners like Finviz, Yahoo Finance, and TradingView provide P/B ratios for most stocks. For deeper analysis, Koyfin and Simply Wall St offer free tiers with balance sheet data. Paid services like Portfolio123 or Bloomberg allow custom screening formulas and historical backtesting. Annual report data (10-K filings) is available free on SEC EDGAR.
Helpful Tools & Resources
Strategy Variations
Explore different ways to implement this strategy, each with its own trade-offs and benefits.
Alternative Value Metrics
E/P: Earnings / Price; EBITDA/EV: Operating earnings / Enterprise value; CF/P: Cash flow / Price; S/P: Sales / Price
Combining metrics adds ~2% annually (Blitz & Hanauer)
Value + Momentum
Value and momentum are negatively correlated. 50/50 allocation reduces volatility significantly. Can use momentum to time value exposure.
Documented across all markets (Asness et al. 2013)
Value + Quality
Avoid value traps with quality screens. Profitability filter: ROE > 10%. Leverage filter: Debt/Equity < 1.0.
Piotroski F-Score is popular quality filter
Industry-Adjusted
Compare B/M within industries only. Tech vs. tech, banks vs. banks. Addresses sector composition bias.
More consistent signal over time
Risks & Limitations
Value underperformed growth by 50%+ from 2007-2020. The longest drawdown in history. Investors who bought value in 2007 waited over a decade. Patience required.
Cheap stocks can be cheap for good reason. Companies facing permanent decline or disruption may never recover. Quality filters help but don't eliminate this risk.
Book value misses intangible assets (software, brands, R&D). Modern tech companies appear expensive because their real assets aren't on the balance sheet.
Value portfolios overweight financials, utilities, industrials while underweighting tech. This sector bet can dominate returns, especially when tech outperforms.
References
- Rosenberg, B., Reid, K., & Lanstein, R. (1985). Persuasive Evidence of Market Inefficiency. Journal of Portfolio Management, 11(3), 9-16 [Link]
- Fama, E. F., & French, K. R. (1992). The Cross-Section of Expected Stock Returns. Journal of Finance, 47(2), 427-465 [Link] [PDF]
- Fama, E. F., & French, K. R. (1993). Common Risk Factors in the Returns on Stocks and Bonds. Journal of Financial Economics, 33(1), 3-56 [Link] [PDF]
- Lakonishok, J., Shleifer, A., & Vishny, R. W. (1994). Contrarian Investment, Extrapolation, and Risk. Journal of Finance, 49(5), 1541-1578 [Link] [PDF]
- Asness, C. S., Moskowitz, T. J., & Pedersen, L. H. (2013). Value and Momentum Everywhere. Journal of Finance, 68(3), 929-985 [Link] [PDF]
- Fama, E. F., & French, K. R. (2015). A Five-Factor Asset Pricing Model. Journal of Financial Economics, 116(1), 1-22 [Link] [PDF]
- Arnott, R. D., Harvey, C. R., Kalesnik, V., & Linnainmaa, J. T. (2021). Reports of Value's Death May Be Greatly Exaggerated. Financial Analysts Journal, 77(1), 44-67 [Link] [PDF]
- Blitz, D., & Hanauer, M. X. (2021). Resurrecting the Value Premium. Journal of Portfolio Management, 47(2), 63-81 [Link] [PDF]
Strategy based on research by Fama & French (1992, 1993). Implementation details represent educational content only. Past performance does not guarantee future results. This is not investment advice.
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