Risk Aversion

Risk aversion quantifies how much an investor dislikes uncertainty. A highly risk-averse investor demands a large premium to accept volatility; a less risk-averse investor will tolerate more volatility for a smaller increase in expected return.

In portfolio theory, risk aversion is parameterized as a coefficient (often denoted γ) in the investor's utility function:

• Low risk aversion (γ ≈ 1-2): tolerates large drawdowns; allocates heavily to equities
• Moderate risk aversion (γ ≈ 3-5): the range assumed in most academic models and target-date fund design
• High risk aversion (γ ≈ 7+): prioritizes capital preservation; allocates heavily to short-duration bonds

Risk aversion determines the optimal mix between risky assets (equities) and safe assets (Treasury bonds). For a given set of expected returns, volatilities, and correlations, a more risk-averse investor holds a lower equity weight. This is the core input to asset allocation decisions.

Empirical evidence suggests risk aversion is not constant — it varies across individuals, changes with wealth, and shifts with age. The lifecycle investing framework accounts for this by recognizing that the ability to recover from losses (via future labor income) effectively lowers the risk aversion relevant for portfolio decisions among younger investors.