Shang Hai Zheng Quan Bao·2025-09-15 19:09Core Viewpoint - The adjustment of the Sci-Tech Innovation 50 Index sample stocks and their weight distribution has attracted significant market attention, particularly in the context of the rapid growth of index funds, which will increasingly influence market dynamics [1][6]. Group 1: Market Impact of Index Adjustments - The adjustment of the Sci-Tech 50 Index sample stocks has led to significant stock price volatility, particularly for companies like Cambrian, which saw a drop of over 14% on September 4 due to anticipated fund outflows [1][2]. - As of September 2, Cambrian's weight in the index was 15.42%, while the top five stocks accounted for 46.23% of the total weight, indicating a potential outflow of approximately 10 billion yuan from Cambrian [1][2]. - Following the index adjustment announcement, Cambrian's weight slightly decreased to 15.38% by September 12, with the total ETF scale tracking the index at 173.917 billion yuan, suggesting continued fund outflows [3][4]. Group 2: Growth of Index Funds - The rapid growth of index funds over the past two years has significantly impacted stock prices, with Cambrian's top ten shareholders including multiple ETFs with a combined market value exceeding 17 billion yuan [4][5]. - The number of ETFs with over 10 billion yuan in scale has increased from 44 at the end of last year to 56 as of September 12, highlighting the growing influence of these funds in the market [5]. Group 3: Interaction Between Index Funds and Market - The interaction between index funds and the market is becoming a normalized issue for investors, particularly during index adjustments, which can lead to significant market disturbances [6][7]. - Analysts suggest that the impact of ETF rebalancing on stock prices diminishes after the adjustment takes effect, indicating a complex relationship between fund flows and market performance [6][7].