Factor investing is the systematic approach of targeting specific, persistent drivers of return across asset classes. What began as academic theory is now a $1.5+ trillion industry — roughly 15% of the total ETF market. This guide explains how factor models work and how to apply them.
The Six Major Equity Factors
1. Value
Stocks trading at low prices relative to fundamentals (book value, earnings, cash flow) have historically outperformed expensive stocks. The value premium averaged approximately 2.9% annualized from 1963 to 2024. The rationale: compensation for distress risk, or behavioral overreaction to bad news.
2. Momentum
Stocks that have recently outperformed tend to continue outperforming over 3–12 month horizons. First documented by Jegadeesh and Titman (1993) in "Returns to Buying Winners and Selling Losers," the momentum effect is driven by behavioral underreaction to information and herding effects.
3. Quality
Profitable firms with strong balance sheets, consistent earnings, and efficient capital allocation outperform. The quality premium captured approximately 4.7% annualized from 1964 to 2023 with a Sharpe ratio of 0.47. Markets persistently underprice durable, high-quality businesses.
4. Low Volatility
Stocks with lower price variability deliver better risk-adjusted returns than high-volatility stocks — violating the core prediction of CAPM. Baker, Bradley, and Wurgler (2011) documented this anomaly in "Benchmarks as Limits to Arbitrage."
5. Size
Smaller companies historically outperform large-caps, compensating for illiquidity and higher information costs. However, the size premium has largely stagnated in recent decades after performing extremely well before 1982.
6. Investment (Conservative)
Companies that invest conservatively (low asset growth) outperform aggressive investors. Aggressive investment often leads to diminishing returns and empire-building.
How Factor Portfolios Are Constructed
There are three primary approaches to building multi-factor portfolios:
- Integrated (Intersectional) — Score each stock on all factors simultaneously, select those scoring well on multiple dimensions. Most capital-efficient but complex. This is the approach used by Blank Capital's Aegis model.
- Sleeve (Combination) — Build separate single-factor portfolios, then allocate to each. Simpler but can create conflicting positions.
- Sequential (Tilt) — Start with one factor screen, then apply subsequent filters.
Portfolios are rebalanced according to predefined rules (typically monthly or quarterly). Transaction cost management is critical, especially for momentum strategies with higher turnover.
The Value-Momentum Combination
Value and momentum are negatively correlated, making them one of the most powerful factor combinations in finance. When value stocks are out of favor, momentum stocks tend to perform well, and vice versa. AQR's research confirms this negative correlation exists across all major equity markets and asset classes.
Adding quality to the mix creates a three-factor combination that has shown remarkable consistency across time periods, geographies, and market conditions.
Smart Beta ETFs: The Reality Check
Smart beta ETFs now manage over $1.5 trillion. However, the evidence on implementation is mixed:
- Market-adjusted returns of smart beta indexes drop from about 3% "on paper" to -0.5% to -1% after ETF listings — much of the premium erodes once capital flows in
- Multi-factor funds may not deliver the best returns, but they tend to consistently beat benchmarks over time
- Cost matters — factor premiums are modest (2–5% annually), so high fees can consume the entire edge
Practical Guidance
- Diversify across factors: No single factor works all the time. Value underperformed for over a decade (2007–2020).
- Expect drawdowns: Factor premiums are compensation for risk — they cycle and can underperform for extended periods.
- Use rules-based discipline: The entire point of quantitative investing is removing emotional interference.
- Keep costs low: Factor premiums are modest, so implementation efficiency matters enormously.
Our methodology page details exactly how the Blank Capital 6-factor model weights quality (30%), momentum (25%), value (15%), investment (10%), stability (10%), and short interest (10%) to create composite rankings for every stock. See the live rankings.