Historically, September has been the worst month for stocks, with the Dow Jones declining an average of 0.8% and the S&P 500 dropping an average of 0.5% since 1950.
"September is generally the worst month for stocks also known as the September effect that's because according to Investopedia since 1950 the Dow Jones has declined an average of 0.8 in September in the S P 500 drops an average of half a percent"