Scott Rubner, Head of Equity and Equity Derivatives Strategy at Citadel Securities, is urging investors to take a more defensive stance ahead of September. In an August 31 note, he recommended trimming market exposure and adding downside hedges while options remained at their cheapest levels of 2026. The warning follows an intraday record of 7,816.70 for the S&P 500 earlier in August, after the index gained nearly 7% from late July into early August. September has historically been the S&P 500's weakest month based on data going back to 1928. Rubner highlighted several factors that could reinforce that seasonal pattern in 2026: corporate buybacks are expected to slow around September 12 as companies enter blackout periods before third-quarter earnings; retail traders' net buying during recent S&P 500 pullbacks has been about half its average since 2019; and systematic strategies, including CTA trend-followers and volatility-control funds, were nearing peak allocations. A busy economic calendar, including the nonfarm payrolls report and the Federal Open Market Committee meeting, adds to the potential volatility. Rubner described the recommendation as tactical rather than a change to Citadel Securities' constructive long-term view of U.S. equities. He has issued similar seasonal cautions in previous years, but the combination of record highs, weaker retail participation, heavily allocated systematic funds and buyback blackouts gives the 2026 warning greater significance, the note said.