What 0DTE Means
0DTE stands for zero days to expiration — options contracts that expire on the same trading day you're looking at them. With daily expirations now listed on SPX, SPY, QQQ, and a growing list of major names, there is a fresh set of same-day contracts to trade every session the market is open.
These contracts have exploded in popularity. On a typical day, 0DTE options account for more than 50% of total SPX options volume — the single largest bucket of activity in the entire index options market. That concentration matters, because where the volume is, the dealer hedging pressure is too.
A 0DTE contract has hours, not weeks, of life left. That compresses everything: theta decays to zero by the close, gamma spikes near the money, and the price behavior around key strikes becomes far more mechanical than it is further out on the curve.
Why 0DTE Dealer Gamma Dominates Intraday
Gamma measures how fast an option's delta changes as the underlying moves. It peaks for at-the-money options and grows sharply as expiration approaches. On expiration day, the expiring strikes carry enormous gamma relative to any other expiration on the board — a small move in the underlying forces a large change in dealer delta.
Because dealers are the counterparty to most of that retail and institutional 0DTE flow, they must continuously re-hedge to stay delta-neutral. On expiry day, that day's dealer gamma is so large it dominates the intraday tape. The rest of the term structure barely registers by comparison — the same-day book is what's actually steering price.
The key insight: on expiration day the expiring strikes' gamma dwarfs everything else on the curve. Whether that gamma is net positive or net negative for dealers decides whether price gets pinned or whipped for the rest of the session.
Pinning: Positive Gamma Magnetizes Toward Max Pain
When dealers are net long gamma (positive gamma), their hedging is stabilizing: they sell into rallies and buy into dips to stay neutral. That mechanical buying and selling drains volatility out of the tape and pulls price toward the strike where dealer gamma is concentrated — usually near max pain, the strike where the most option value expires worthless.
This is the classic pin. As the close approaches and gamma intensifies, the magnetic pull toward max pain strengthens. Positive-gamma expiry days often close with the index hugging a round-number strike, having gone nowhere despite plenty of intraday noise.
The strength of the pin depends on how far spot is from max pain. Sitting right on it with positive gamma is the strongest pin; drifting within the day's expected move is a moderate pin; being far away is a weak pin that a real catalyst can break.
When It Is NOT a Pin: Negative Gamma Amplifies
The pin is not guaranteed. When dealers are net short gamma (negative gamma), the hedging flips sign and becomes destabilizing: dealers must sell into weakness and buy into strength, adding fuel to whatever direction price is already moving. Instead of dampening moves, they amplify them.
On a negative-gamma 0DTE day, don't expect a quiet pin into the close. Expect trend and volatility — breakouts that run, gaps that extend, and moves that feed on themselves as dealers chase. The same expiration-day gamma that pins price in a positive regime is exactly what accelerates it in a negative one.
Warning: never assume a pin. The regime, not the calendar, decides the day. Positive gamma pins toward max pain; negative gamma does the opposite and amplifies moves into the close. Always check which regime is live before you fade a move on expiration day.
Reading the 0DTE Panel on greeks.pro
The 0DTE focus panel (/api/analytics/zero-dte, available on Pro+) isolates only today's expiring contracts and computes GEX, the gamma flip, max pain, and the expected move from that single expiration — then distills it into a plain-English pin-risk read. Key fields include pinRisk, read, and isTrue0DTE, alongside the expiration, gammaFlip, maxPainStrike, and expected-move bounds.
The panel returns one of four verbatim reads depending on the gamma regime and how far spot sits from max pain:
| Read string | pinRisk | What to expect |
|---|---|---|
| positive gamma, spot hugging max pain — strong pin risk into the close | high | Strong magnet toward max pain; low odds of a big move |
| positive gamma, spot within today's expected move of max pain — moderate pin | moderate | Pull toward max pain, but reachable within the expected move |
| positive gamma but spot far from max pain — weak pin; a break can run | low | Weak pull; a catalyst can break spot loose and let it run |
| negative gamma — dealers amplify moves; expect trend/volatility into close, not a pin | n/a (amplify) | No pin; dealers add fuel — plan for trend and volatility |
The first three reads are the positive-gamma cases, ordered by how tightly spot is bound to max pain — high, then moderate, then low pinRisk. The fourth is the negative-gamma case, where there is no pin to speak of and the honest signal is to expect amplification instead.
An honesty feature, not a bug: when nothing actually expires today — a weekend, or a symbol without daily expiries — isTrue0DTE returns false. The panel falls back to the nearest expiration and reports pinRisk "n/a" rather than pretending there's a live 0DTE pin. If it isn't a real expiry day, the panel tells you so instead of inventing a signal.
Risk Warning: 0DTE Is High-Risk
0DTE options are among the highest-risk instruments retail traders touch. The same properties that make them compelling make them dangerous:
- Theta is brutal. Time value evaporates over the course of a single session — a contract can go from meaningful premium to zero in hours, and being right on direction but early or wrong on timing still ends at zero.
- Gamma is explosive. Near-the-money 0DTE delta swings violently with small moves in the underlying. Positions can flip from deeply profitable to worthless — or the reverse — in minutes.
- Regime can shift. A day that starts pinned in positive gamma can cross the gamma flip and turn into an amplifying, trending tape. Reads describe the current regime, not a guarantee for the rest of the session.
Treat the 0DTE panel as context for how dealer positioning is likely to shape the tape — not as a signal to size up. Position small, define your risk, and respect that on expiration day the math moves fast in both directions.