Low Idiosyncratic Volatility and Higher Expected Returns in A-Shares

Summary

This research summary examines the low idiosyncratic volatility effect in China’s A-share market. It estimates volatility from the annualized standard deviation of residuals in CAPM, Fama–French three-factor, and Carhart four-factor regressions fitted to the prior month’s daily data. The authors argue that the three-factor residual measure captures stock-specific risk more fully than raw return volatility or the CAPM residual measure.

Across cross-sectional comparisons and equal-weighted portfolios grouped by volatility, lower idiosyncratic volatility is associated with higher future excess returns. The three-factor measure shows the strongest predictive relationship and portfolio results, which the summary says persist under industry neutrality and across strong bull and bear markets. Low-volatility selections also tend toward larger-cap, cheaper, recently weaker-performing, and lower-turnover stocks; turnover explains the pattern most, followed by reversal and valuation, but these factors do not fully account for it. The claims rely on historical data, and the authors caution that changing market styles could weaken the result.

Key ideas

• The study measures idiosyncratic volatility using residuals from factor models fitted to prior-month daily returns.
• Three-factor residual volatility is presented as a more complete stock-specific risk measure than raw volatility or CAPM residual volatility.
• Lower idiosyncratic volatility is associated with higher future cross-sectional excess returns in the studied A-share market.
• The three-factor measure produces the strongest reported predictive relationship and portfolio results.
• Turnover, reversal, and valuation explain part of the pattern, while historical dependence limits generalization.

Tags

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.