The Defensive Premium Across Asset Classes

Standard finance theory says riskier assets should earn higher expected returns to compensate investors for bearing more risk. In practice, across equities, bonds, and even currencies, the opposite has often shown up on a risk-adjusted basis: low-beta stocks have delivered better Sharpe ratios than high-beta stocks, high-grade bonds have outperformed junk bonds after adjusting for volatility, and low-volatility currencies have beaten high-volatility ones per unit of risk taken. This is the defensive or low-risk premium, and it's one of the more robust anomalies documented across markets.

The leading explanation is leverage aversion: many real-world investors (pension funds, retail investors, mutual funds with leverage restrictions) can't or won't use borrowed money to scale up a safe, low-volatility bet into higher returns, so instead they buy riskier, higher-beta assets directly to reach their desired return target. That structural tilt of demand toward risky assets bids their prices up and expected returns down relative to what a leverage-unconstrained investor would demand, leaving safer assets comparatively cheap — the reverse of the textbook risk-reward relationship.

A "betting against beta" strategy exploits this directly: it goes long low-beta stocks (leveraged up to a target market exposure) and short high-beta stocks (delevered down to the same target), aiming to profit from the low-beta side's better risk-adjusted returns while staying roughly market-neutral overall.