Historical volatility is a measure of how volatile a stock price has been over a period of time. Typically, historical volatility is negatively correlated with stock returns, which is consistent with the low volatility anomaly. This anomaly suggests that stocks with low historical volatility tend to provide higher risk-adjusted returns, possibly because the market underprices low volatility stocks. This phenomenon may be influenced by behavioral finance factors, such as investors' excessive pursuit of high-volatility stocks and neglect of low-volatility stocks. In addition, low-volatility stocks may show greater resilience in certain market environments (such as when the market is down). It should be noted that historical volatility only reflects past volatility and cannot fully predict future volatility.