Idiosyncratic Volatility as a Factor in Chinese A-Share Stocks

Summary

The report estimates stock-specific volatility from residuals in CAPM, Fama-French three- and five-factor, and Carhart four-factor models, then studies its role in China’s A-share market. It describes a low-volatility portfolio that equally weights stocks in the lowest 30% by estimated idiosyncratic volatility and compares it with an equally weighted market benchmark. From May 2005 to February 2018, the reported annualized excess return is 7.55%, with 4.67% tracking error, a 1.62 information ratio, and 5.85% maximum drawdown.

The report also finds limited overlap between idiosyncratic volatility and traditional factors, and estimates a negative average monthly pure-factor return using a market-cap-weighted regression that isolates volatility exposure. In size groups, a market-neutral long-short portfolio based on low versus high idiosyncratic volatility earns higher annualized returns under multi-factor models than under CAPM. These are historical results from one market and sample period; the summary gives no implementation costs or evidence that the effects persist out of sample.

Key ideas

• Idiosyncratic volatility is measured as the volatility of returns unexplained by a chosen factor model.
• The lowest-volatility 30% portfolio outperformed an equally weighted A-share benchmark over the stated sample.
• Traditional style factors had limited explanatory power for idiosyncratic volatility in the reported analysis.
• Size-grouped long-short results were stronger under the multi-factor models than under CAPM.
• The findings are historical and do not establish persistence after the sample period or trading costs.

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