股票股指期权：下行降波，偏度正偏回落，可考虑卖出看涨期权

1. Report Industry Investment Rating - Not provided in the given content 2. Core View of the Report - In the stock index option market on August 8, 2025, there was a downward trend in volatility, and the positive skew declined. It is recommended to consider selling call options [1] 3. Summary by Related Catalogs 3.1 Market Data Statistics - Underlying Market Statistics: The closing prices of major indices and ETFs generally declined. For example, the Shanghai Composite 50 Index closed at 2789.17, down 9.14 points; the CSI 300 Index closed at 4104.97, down 9.70 points. Trading volumes also decreased in most cases, such as the Shanghai Composite 50 Index with a trading volume of 38.92 billion hands, a decrease of 3.41 billion hands [2] - Option Market Statistics: Trading volumes of most option contracts decreased, while some open interest increased. For instance, the trading volume of Shanghai Composite 50 Index options was 29,318, a decrease of 3,056, and the open interest was 74,682, a decrease of 361 [2] - Option Volatility Statistics: The implied volatility (IV) of most options decreased, and the historical volatility (HV) showed different trends. For example, the ATM - IV of Shanghai Composite 50 Index options was 11.69%, a decrease of 0.06%, and the 20 - day HV was 6.72%, a decrease of 2.69% [5] 3.2 Option Analysis by Type - Shanghai Composite 50 Index Options: Analyzed through full - contract PCR, main - contract skew, volatility cone, and volatility term structure charts [8][9] - CSI 300 Index Options: Similar analysis methods were used as the Shanghai Composite 50 Index options, including full - contract PCR, main - contract skew, volatility cone, and volatility term structure [12][13] - CSI 1000 Index Options: Analyzed using full - contract PCR, main - contract skew, volatility cone, and volatility term structure [15][16] - ETF Options: Options such as Shanghai Composite 50 ETF, Huatai - Baorui 300 ETF, and others were analyzed in terms of full - contract PCR, main - contract skew, volatility cone, and volatility term structure [19][20][24]