LEARN — 0DTE
Zero-days-to-expiration options now account for over half of SPX volume. Their extreme gamma creates massive intraday hedging flows that reshape market structure by the hour. Understanding 0DTE gamma is essential for any intraday trader.
An option expiring today has one property that makes it structurally unique: its gamma is extreme. As expiration approaches, the gamma of an at-the-money option increases dramatically. A $1 move in the underlying can flip the option from worthless to deep in-the-money — and the dealer's hedging requirement changes with equal violence.
This means 0DTE options at strikes near the current price create enormous hedging obligations on very short timescales. A single strike with heavy 0DTE open interest can generate more hedging flow than an entire chain of monthly options.
CBOE reports that over 59% of SPX options volume now trades in 0DTE contracts. This is not a niche product — it is the dominant force in S&P 500 options. The structural impact of this volume is massive and growing.
Pinning near high-OI strikes: When large 0DTE open interest exists at a round-number strike, the extreme gamma creates intense hedging flows that can "pin" price near that level. Moves away from the strike trigger hedging that pushes price back.
Explosive breaks: When price moves far enough from the pinned level, the gamma exposure at that strike drops rapidly (the options go deep ITM or OTM), and the pinning force disappears. This can cause sudden acceleration — the market was held in place by structural forces, and when those forces release, it moves fast.
Charm acceleration into the close: As 0DTE options decay through the afternoon, charm (delta decay) forces dealers to continuously adjust their hedges. This creates a steady flow of buying or selling that intensifies toward the close. The final hour of trading on a day with heavy 0DTE positioning can be dominated by charm-driven dealer flows.
Many gamma exposure platforms compute GEX from overnight snapshots. By the time markets open, yesterday's 0DTE options have expired and today's 0DTE data is not yet reflected. This means their GEX map is missing the single largest source of intraday structural flow.
Gamma Sonar includes 0DTE gamma from market open. Pre-market structural levels computed by 6:35 AM ET already account for today's 0DTE expiry. Throughout the session, live greeks on SPX and major indices are recomputed every 60 seconds — capturing the rapidly shifting gamma landscape as 0DTE positions evolve.
Gamma Sonar recomputes GEX from live greeks every 60 seconds on SPX, SPY, QQQ, and major indices — plus 90+ additional tickers on 5-minute cycles.
START 7-DAY FREE TRIAL →Gamma Sonar provides structural analytics for educational purposes only. Not financial advice. All models involve assumptions. Past patterns do not guarantee future results.