A股午后突发跳水，三大股指放量下跌，两市成交额逼近2万亿，究竟发生了啥？大跌原因找到了

Market Overview - A-shares experienced a sudden decline, with the three major indices dropping over 1% in the afternoon session, which was unexpected [1][4] - The Shanghai Composite Index closed down 1.18% at 3573.21 points, the Shenzhen Component Index fell 1.73% to 11009.77 points, and the ChiNext Index decreased 1.66% to 2328.31 points [1][2] - Nearly 4300 stocks in the market declined, indicating a broad-based sell-off [1] Trading Volume and Market Sentiment - The trading volume for the day reached 1.96 trillion yuan, an increase of 917 billion yuan compared to the previous trading day, indicating heightened market activity [2][4] - The market sentiment was mixed, with only a few sectors like assisted reproduction and liquid cooling IDC showing positive performance, while cyclical sectors like steel and coal faced significant declines [1][4] Sector Performance - Cyclical sectors, which had previously been performing well, saw a collective downturn, with stocks like Anyang Iron & Steel and Antai Group dropping over 7% [1][4] - The financial sector also struggled, with stocks such as China Zhongjin Securities and China Life Insurance falling more than 4% and 5% respectively [1] External Factors Influencing the Market - The recent adjustment in A-shares may be attributed to several factors, including profit-taking by investors after a period of gains, particularly in cyclical stocks and innovative pharmaceuticals [4] - Concerns over the security risks associated with Nvidia's H20 computing chips, which were recently allowed to resume sales in China, have also contributed to market volatility [4][5] - The release of July's manufacturing PMI, which showed a slight decline to 49.3%, indicates a cooling in manufacturing activity, further impacting market sentiment [6] Future Outlook - Analysts suggest that while core indices may challenge their yearly highs, the path forward may not be smooth, necessitating close attention to policy implementation, economic data validation, and external environmental changes [7]