Fama-French Factors.
A definition, in plain English — with the books that teach it.
What it means
Fama-French factors are systematic return drivers identified by Eugene Fama and Kenneth French that extend CAPM. The original three-factor model adds size (small-cap stocks historically outperform large-cap) and value (high book-to-market stocks outperform growth) to market beta. A later five-factor extension adds profitability and investment. Factor-based investing — loading on these risk premia intentionally — underpins many index-plus strategies and smart-beta ETFs. Whether these factors represent genuine risk compensation or behavioral mispricing remains debated.
Example
A small-cap value ETF is engineered to score high on the size and value Fama-French factors. Over long periods, this tilt has historically added 1-3% annualized above the market factor alone — though the premium can go dormant for a decade, as value did during 2010-2020.
