The Kobeissi Letter(@KobeissiLetter):History suggests volatility is ahead. Since 1928, the S&P 500 has fallen ~55% of the time in September, making it the only month of the year when negative returns have occurred more often than positive returns. Over this period, the average return of the index has been -1.1%, with an average drawdown of -4.7%. Furthermore, the best September recorded a +14.4% gain, while the worst saw a -29.9% decline. The weakness has historically been concentrated later in the month, with the second half of September averaging a -0.9% return, making it the weakest 2-week period of the year. By comparison, the first half has seen an average decline of -0.2%. September has historically been a weak month for US stocks.

2026.09.03 14:02

History suggests volatility is ahead. Since 1928, the S&P 500 has fallen ~55% of the time in September, making it the only month of the year when negative returns have occurred more often than positive returns. Over this period, the average return of the index has been -1.1%, with an average drawdown of -4.7%. Furthermore, the best September recorded a +14.4% gain, while the worst saw a -29.9% decline. The weakness has historically been concentrated later in the month, with the second half of September averaging a -0.9% return, making it the weakest 2-week period of the year. By comparison, the first half has seen an average decline of -0.2%. September has historically been a weak month for US stocks.