Group 1 - The core viewpoint of the article highlights that despite the recent rise in the U.S. stock market, key support forces are showing signs of weakening, leading to potential risks in September [1][21] - Retail investors have been a significant driving force behind the recent rebound in the U.S. stock market, with net buying occurring on 27 out of the last 28 trading days [4][20] - Systematic funds, which have injected over $365 billion into global markets in the past 75 trading days, are nearing their capacity limits, which may reduce their role as stabilizing buyers [9][12] Group 2 - Historical data indicates that retail trading activity typically peaks in June and July, then declines in August, reaching its lowest point in September, suggesting a loss of a key buying force [6][16] - The article warns of a "support vacuum" as retail buying wanes and institutional buying exhausts, particularly in September, which is historically the worst-performing month for the S&P 500 index [2][17] - Despite strong earnings reports, with 85% of companies exceeding expectations, these positive factors may not be enough to counteract the dual pressures from funding and seasonal trends [20][21] Group 3 - The article emphasizes that the market's ability to withstand negative macroeconomic news will be significantly weakened, preparing investors for potential higher volatility [3][21] - The article also notes that volatility control strategies may see a slowdown in buying demand due to recent increases in volatility, while risk parity strategies are returning to historical levels [13][14]