The small cap premium describes the historical excess return of small-cap stocks over large-cap stocks. It is treated as a size factor in asset pricing models and factor investing, reflecting the idea that smaller companies have different risk and return characteristics than larger ones.
In models such as the Fama-French Three-Factor Model, the SMB (Small Minus Big) component represents the return difference between portfolios of small-cap and large-cap stocks. Investors and portfolio managers may tilt toward smaller companies as part of a broader style or factor approach, using this tilt to explain or attribute performance and to set expectations for risk and return in a diversified framework.
The small cap premium is a historical observation, not a guaranteed or constant effect. It has varied across time and markets and is accompanied by higher volatility and liquidity risk for smaller firms. As a result, a small-cap tilt can change a portfolio's risk profile and exposure during market stress. Understanding the premium involves considering horizon, diversification, and how it interacts with other factors and the overall investment objective.
Example: A portfolio with a modest small-cap tilt may exhibit higher average returns over long horizons compared with a broad-market benchmark, while also showing greater volatility.
Size factor (SMB) · Fama-French Three-Factor Model · Market Capitalization · Small-cap stocks · Factor investing · Risk premium