股票股指期权：下行升波，可考虑买入看跌期权保护

1. Report Industry Investment Rating - No relevant content provided 2. Core View of the Report - With the downward increase in volatility, it is advisable to consider buying put options for protection [2] 3. Summary of Key Information from the Report a. Market Data Statistics - Underlying Market Statistics: On November 18, 2025, the closing prices of the Shanghai - Shenzhen 300 Index, CSI 1000 Index, and most of the ETFs declined. For example, the Shanghai - Shenzhen 300 Index closed at 4568.19, down 29.86 points; the CSI 1000 Index closed at 7448.10, down 74.98 points. Trading volumes also showed changes, with some increasing and some decreasing [3]. - Option Market Statistics: Volumes and open interests of various options changed. For instance, the volume of CSI 1000 index options increased by 45561 to 323505, and the open interest increased by 5348 to 335884. The VL - PCR and OI - PCR values varied across different options [3]. - Option Volatility Statistics: The implied volatility (IV) of most options increased, while the historical volatility (HV) showed different trends. For example, the near - month ATM - IV of Shanghai - Shenzhen 300 index options increased by 2.47% to 16.32%, and the 20 - day HV decreased by 13.74% to 8.41% [6]. b. Option - Specific Figures - Multiple figures are presented for each type of option, including full - contract PCR, main - contract skewness, volatility cones, and volatility term structures, which help in analyzing the market trends and characteristics of different options [10][14][18]