公告与预测对比及超预期分析：12月A股指数调样会带来哪些投资机会

• The report introduces a comprehensive impact coefficient model to measure the impact of multiple index adjustments on individual stocks. The model is defined as follows: $effect_total_{s}=\sum_{i=1}^{n}\frac{wt_chg_{s_{i}}\times fund_size_{i}}{amount_avg_{s_{i}}20}$ where $effect_total_{s}$ represents the comprehensive impact coefficient of stock $s$ across sample indices, $wt_chg_{s_{i}}$ is the estimated weight change of stock $s$ in index $i$, $fund_size_{i}$ is the tracking scale of index $i$, and $amount_avg_{s_{i}}20$ is the average trading volume of stock $s$ over the past 20 days[11] - The report highlights the impact of index sample stock adjustments on individual stocks, focusing on the December 2025 periodic adjustments of major indices such as CSI 300, CSI A500, and SSE 50. The analysis includes the calculation of the comprehensive impact coefficient for stocks being added or removed from indices, as well as the potential passive trading impact due to weight adjustments[13][14][16] - The report identifies stocks with significant positive and negative impact coefficients due to index adjustments. For example, stocks like Tower Group, Jiangzhong Pharmaceutical, and Zhengbang Technology have positive impact coefficients above 2, while stocks like Deep Expressway and Wanhe Electric have significant negative impact coefficients[16][17][18] - The report evaluates the impact of weight cap adjustments for stocks like Zhongji Xuchuang and Xinyisheng in thematic indices such as CS Artificial Intelligence and Communication Equipment. Due to exceeding the weight cap, these stocks are expected to experience passive outflows of approximately 6.3 billion yuan and 2.7 billion yuan, respectively. However, the report concludes that the negative impact is limited due to sufficient liquidity and potential inflows from other indices[5][19][20]