TOPSHOT - A trader works on the floor of the New York Stock Exchange (NYSE) at the opening bell in New York City on March 10, 2025. (Photo by CHARLY TRIBALLEAU / AFP) (Photo by CHARLY TRIBALLEAU/AFP via Getty Images)AFP via Getty ImagesThe stock market's monthly performance exceeded expectations again in September 2025 as the S&P 500 was up 2.3% just a bit less than the 2.6% gain in September 2023. In both years, it seems as though the historically weak performance of the S&P 500 in September influenced inv ...