Citadel Securities strategist Scott Rubner expects retail investors to pull back from aggressive stock purchases in September, interrupting a months-long buying spree that has buoyed U.S. equity markets. Rubner said activity should pick up again later in the fourth quarter once seasonal headwinds ease. Retail traders have been net equity buyers in 16 of the past 18 weeks, according to Citadel data, and options volume tied to individual investors sits in the 98th percentile of historical readings. Tesla, Nvidia and UnitedHealth remain among the most actively accumulated names. Rubner’s caution aligns with the market’s long-held wariness toward September, historically the weakest month for the S&P 500. Analysts point to portfolio rebalancing, thinner post-summer liquidity and a dearth of near-term catalysts as factors that could amplify volatility this year before a potential rebound heading into year-end.