Historically, the final week of September has been brutal for US stocks. Wall Street didn’t get the memo. A week that should be worseData from equity analysts and calendar trend watchers often pin this week, the last full trading week of September, as the worst week for stocks all year. In fact, since 1945, the S&P 500 has posted negative returns roughly 60% of the time during this week, with average declines of more than 1%. In 2022, for example, the S&P 500 fell nearly 5% across this same stretch, the worst performance in months, driven by fears of an aggressive Fed and rising bond yields.