Systematic Sources of Excess Returns

Factor investing is a strategy that targets specific drivers of returns identified by decades of academic research. Instead of picking individual stocks, factor investors systematically tilt their portfolios toward characteristics that have historically produced excess returns above the market — known as risk premia or factor premia.

The Five Major Equity Factors

1. Value

Stocks that are cheap relative to fundamentals (low P/E, P/B, P/CF) tend to outperform expensive stocks over time. The value premium has been documented since the 1930s and exists across global markets. Value's underperformance from 2010-2020 was historically unusual, leading some to declare the factor "dead" — right before it came roaring back in 2022.

2. Momentum

Stocks that have performed well over the past 6-12 months tend to continue performing well in the near term. Momentum is one of the strongest factors but also experiences periodic crashes (momentum reversals at market turning points). Combining momentum with value (buying cheap stocks with positive momentum) improves risk-adjusted returns.

3. Quality

Profitable, stable companies with strong balance sheets and high returns on capital outperform less-profitable, leveraged companies. Quality metrics include high ROE, low debt, stable earnings growth, and high margins. Quality tends to perform best during market downturns — investors flee to safety.

4. Size (Small-Cap)

Smaller companies have historically outperformed larger companies over long periods, though the effect has weakened in recent decades. The size premium is debated — some argue it's been arbitraged away, others note that small-cap outperformance is episodic but powerful when it appears.

5. Low Volatility

Counterintuitively, lower-volatility stocks have historically produced higher risk-adjusted returns than higher-volatility stocks. This contradicts traditional finance theory (which says higher risk = higher returns) and is attributed to behavioral biases — investors overpay for lottery-like high-volatility stocks and underpay for boring low-volatility stocks.

Combining Factors

Factors go through cycles of outperformance and underperformance. Value might dominate for 5 years, then go dormant while momentum thrives. Multi-factor strategies combine several factors to smooth out these cycles — when one factor is struggling, others may be thriving. This is the approach used by most factor ETFs.

Practical Implementation

Multi-factor ETFs — Funds like LRGF (iShares US Equity Factor), VFMF (Vanguard US Multifactor), or QDF (FlexShares Quality Dividend) provide one-ticket factor exposure.
Single-factor ETFs — Want to tilt heavily toward value? RPV or VTV. Quality? QUAL. Momentum? MTUM. Low volatility? USMV.
Factor tilts within a core portfolio — Keep 60-70% in broad market ETFs, then tilt 30-40% toward factors you believe in. This captures market returns plus any factor premium without betting the farm on factors.

Key Takeaways

Factors are systematic drivers of returns identified by academic research: value, momentum, quality, size, low vol.
Factors go through cycles. Multi-factor strategies smooth the ride.
Tilt toward factors you believe in rather than making all-or-nothing factor bets. Core + satellite approach works well here.