Factor Investing Premiums Reference
Direct answer: Factor premiums are systematic return differences that have persisted over long periods. The equity risk premium (stocks over T-bills) averages about 5-6% annually over 90+ years. Value, size, and momentum premiums each average 2-5% annually, though all are cyclical and can underperform for a decade or more.
Historical Factor Premiums (U.S., ~1963-2024)
| Factor | Long-Short Premium (ann.) | Sharpe Ratio | Key Metric | Worst Decade |
|---|---|---|---|---|
| Market (ERP) | +5.5% over T-bills | 0.42 | Beta vs. market | 2000s (-1.0%/yr) |
| Value (HML) | +3.7% | 0.31 | Book/Price ratio | 2010s (-3.1%/yr) |
| Size (SMB) | +2.9% | 0.24 | Market cap | 1980s (+1.1%/yr) |
| Momentum (UMD) | +7.8% | 0.50 | 12m-1m return | 2009 crash (-84%) |
| Profitability (RMW) | +3.6% | 0.49 | Operating profit | 2000s (modest) |
| Investment (CMA) | +3.0% | 0.45 | Asset growth | Varies |
| Low Volatility | +1.8% (risk-adj) | 0.35 | Beta/Idio. vol. | 2017-2019 |
| Quality | +3.5% | 0.48 | ROE/Accruals | Limited data |
Source: Fama-French Data Library, AQR Capital Management research. Last verified: September 2026.
Frequently Asked Questions
What is factor investing?
Factor investing (also called smart beta or systematic investing) targets specific, documented return premiums beyond market exposure. Factors are characteristics that have historically predicted higher returns, such as low valuation (value), small market cap (size), or recent price momentum.
Are factor premiums reliable?
Factor premiums are real but cyclical and uncertain. All major factors have experienced decade-long periods of underperformance. Value underperformed for the entire 2010s. Investors must have conviction in the factor's theoretical basis and long time horizons to capture premiums without abandoning the strategy during drawdowns.
How do I implement factor investing?
Most retail investors access factors through factor ETFs (Dimensional Fund Advisors, AQR, iShares, Vanguard) or through direct indexing services. Tilting toward multiple uncorrelated factors (e.g., value + momentum) provides more consistent premium capture than any single factor, since factor premiums are largely uncorrelated.