The S&P 500 experienced a significant decline on the first trading day of September 2024, marking the 30th instance where the index started a month with a 2% drop. Historically, 69% of the time the S&P 500 has closed higher for the month following such a drop, with an average gain of 3.4%. However, past data also shows that September has seen some of the worst rest-of-month returns, notably in 1974 and 2002, with declines of 9.9% and 7.1% respectively. Year-to-date in 2024, the S&P 500 has fallen an average of 0.24% on the first trading day of the month, but has typically seen a gain of 0.3% on the second day if the first day was negative. Similar drops were observed in May '20 and April '20.