Overview
- The triple witching that hit markets Friday, Sept. 18, 2026, caused roughly $7 trillion in U.S. options notional to expire, a volume Citadel Securities says is the second-largest on record.
- Citadel’s market intelligence team reported that about 60% of the expiries executed at the market open, concentrating liquidity and making prices more sensitive to early order flow.
- Dealer gamma is currently positive at about $883 million, which is providing a stabilizing cushion, but that support would weaken if the S&P 500 tracker SPY falls below the 761.34 gamma-flip level.
- SPY trades near 762.70 and faces added pressure from the Federal Reserve’s recent 25 basis point hike to a 3.75%–4.00% range and historically weak September seasonality.
- Historically, roughly 75% of September triple-witching events finished lower five trading days later, so traders should watch whether options-related support holds or prompts amplified volatility and rapid rebalancing that could affect portfolios and short-term liquidity.