Writing from a multi-country global roadshow, Scott Rubner of Citadel Securities published his latest Global Market Intelligence report1 on September 18, 2026, with a diagnosis notable for its clarity and candor. "The biggest change I have noticed," he says, "is how quickly sentiment around AI has turned negative." The tactical conclusion follows directly: "cautious into the end of September, increasingly constructive on what comes next." That tension between near-term caution and forward constructiveness defines the entire piece.
The Surface Held. The Damage Did Not.
The S&P 500 is down 1.8% month-to-date and 3.2% from its August 13 peak. Nine of eleven sectors are lower month-to-date. Only Energy and Communication Services, together representing 14% of the index, have added value since the August high. Information Technology, Industrials, and Consumer Discretionary account for the entire decline in index points. "This has been a meaningful drawdown under the surface," Rubner says, "but importantly, it has remained rotational rather than disorderly."
What has kept the headline number contained is structural. The ten largest S&P 500 constituents now represent approximately 40% of the index by weight, a level not seen since at least 1995. "The concentration of the index has helped cushion the headline drawdown," Rubner notes, allowing the benchmark to appear resilient while the average stock absorbs considerably more pressure.
A Selective Hedge, Not a Broad Panic
The volatility structure tells a precise story. SPX one-month normalized put/call skew has moved from the 5th percentile at the start of September to the 62nd percentile. NDX sits at the 70th; RUT at the 83rd. But the hedging bid is concentrated at the index level. Technology sector skew sits at only the 40th percentile; Industrials at the 31st; Consumer Discretionary at the 12th. "Investors are paying up to hedge the market," Rubner says, "but we are not seeing the same scramble for protection underneath it." One-month implied correlation has risen to approximately 14.5%, the highest since early June. "Unlike the July selloff," he adds, "the current weakness has not been accompanied by the same single-stock volatility or positioning stress." That distinction, at this stage of the move, is material.
On the retail side, the pattern is disengagement rather than capitulation. Semiconductor flow on Citadel's platform is tracking 46% below the June peak, with opening bullish options premium down 45%. Yet the directional bias in semis remains 3% better to buy. "Retail has not capitulated in AI names," Rubner states plainly. "This is a participation story, not a liquidation story."
Into Month-End: Supply Wins
The mechanics through September 30 remain unfavorable on several fronts simultaneously. Vol-targeting strategies are running at approximately 86% equity exposure, the highest since March. CTA US Equity z-scores have retreated from +2.4 at end of August to +1.1. "That is a reduction, not a full unwind," Rubner notes, "leaving CTAs with room to sell further on additional weakness into quarter-end."
The quarter-end rebalance adds mechanical pressure. The S&P 500 is up approximately 1% in Q3 while bonds are down 2.2%, creating an imbalance pension funds have structural incentives to correct. The top 100 US pension plans are approximately 112% funded, the highest since 2001. "Strong funding levels continue to incentivize plans to de-glide and immunize portfolios," Rubner explains, "creating the potential for mechanical equity selling and fixed income buying into quarter-end."
This week's triple-witching expiry compounds the setup: approximately $7 trillion in US equity options notional expires, the second-largest quarterly expiry on record, representing 25% of total US options exposure. And buybacks are moving into blackout. Today, 10% of S&P 500 weight is restricted; by September 30, that figure rises to 61%, with the window not fully reopening until November 1. "One of the market's largest structural buyers," Rubner states, "is stepping aside during exactly the window when the calendar is weakest." Historical midterm-year seasonality confirms the setup: the average path has declined approximately 1.1% between now and September 30.
After September, the Setup Turns
The constructive case assembles itself once the calendar clears. "A lot of the excess we wanted to see come out of the AI trade has now come out," Rubner says. Leveraged semiconductor AUM is roughly half its June peak. Many equipment and infrastructure names are 30% to 55% below their highs. The roadshow conversation has shifted "remarkably quickly from euphoria to fear." The sentiment reversal is striking: "three months ago, the risk was that everyone was in the same trade. Increasingly, the risk is that everyone has moved to the same side of the conversation."
The implications for the index are direct. Technology and Communication Services represent nearly half of the S&P 500, and it is precisely within that complex where positioning and leverage have cleaned up most. "And if AI leadership broadens again into earnings," Rubner adds, "the rally can extend well beyond the names that led the first leg." Q4 seasonality in midterm years averages a gain of 5.6% from September 30, versus 2.9% across all years. Buybacks reopen near November 1. Q2 earnings delivered approximately 33% EPS growth and, in Rubner's assessment, "the steepest positive revision path since at least 2000." The conclusion leaves little ambiguity: "we would use further weakness into month-end to add to core longs."
Five Key Takeaways for Advisors and Investors
- September is not finished. Supply/demand dynamics, buyback blackouts, a $7 trillion options expiry, and pension-driven quarter-end rebalancing all point to continued near-term pressure through September 30. The historical midterm-year pattern supports more downside before stabilization.
- The selloff is rotational, not disorderly. Nine of eleven sectors are lower, but single-stock stress is materially lower than the July episode. Index-level protection has repriced significantly; sector-level hedging has barely moved. That asymmetry signals elevated anxiety without systemic fracture.
- Retail has disengaged from AI names, not abandoned them. Semiconductor flow is 46% below the June peak, but the directional bias remains marginally bullish. The speed and depth of recovery in that complex once seasonality turns depends heavily on whether that participation returns.
- Positioning in AI-linked trades has been substantially reduced. Leveraged semiconductor AUM is half its June peak, and many infrastructure names are 30% to 55% off their highs. The crowded long from the summer has become a crowded skeptic heading into Q4. That is a setup, not a conclusion.
- The Q4 outlook is increasingly constructive. Historical midterm-year seasonality averages a 5.6% gain from September 30. Buybacks return in early November alongside fresh Q3 authorizations. Earnings follow a strong revision cycle, and the AI complex enters October with cleaner positioning and deeply negative sentiment. Rubner's tactical guidance: use further September weakness to add to core longs.
Footnote:
1 Rubner, Scott. "2H September: Getting Closer." Citadel Securities Global Market Intelligence, 18 Sept. 2026, www.citadelsecurities.com/news-and-insights/global-market-intelligence/2h-september-getting-closer/.
