Why it moves faster
Zero-days-to-expiry options expire the same day they trade. The index most associated with them offers a fresh one every weekday, which means expiration-style gamma mechanics now play out every single session rather than once a month. Same-day contracts now account for roughly sixty percent of that index's options volume, with near-at-the-money gamma peaking in the afternoon and moving the futures market directly.
Near-the-money 0DTE contracts carry extreme positive gamma, acting as a strong magnet toward the at-the-money strike. Out-of-the-money contracts sit near zero delta right up until price nears the strike, then "snap" as delta surges. Compressing the whole cycle into a single day produces faster, sharper moves than the same mechanics spread across weeks.
The intraday schedule
The session runs a repeatable shape. From the open to mid-morning, positioning accumulates. Through late morning, the market consolidates as walls form. Midday brings a lull — the quietest stretch of the session.
Early-to-mid afternoon brings the gamma surge — the session's peak, and the point where 0DTE mechanics are most visible on the tape — before gamma collapses into the close in the final hour as the day's contracts stop mattering entirely.
Layering across expirations
0DTE contracts give intraday precision — what expires today. Weekly contracts give a daily bias. Monthly contracts, carrying the highest open interest, give the swing structure that is most reliable across sessions.
When levels from all three layers line up, that confluence marks the strongest structure on the map; treat any single layer's level as a reference zone rather than a guarantee. Macro events — a rate decision, a data print — can override 0DTE structure entirely, and a crowded 0DTE setup tends to self-defeat once everyone is positioned the same way.
Same-day metrics
Expected Move is the implied one-day range priced into today's 0DTE options — roughly the at-the-money straddle price — the number the rest of the session's structure plays out around. Gamma Acceleration is the ratio of 0DTE gamma to seven-day gamma; a rising ratio means today's structure is being driven almost entirely by same-day expiration rather than the weekly layer beneath it.
Theta Decay, expressed per hour rather than per day, is the number that actually matters intraday — a 0DTE option's entire lifetime is one session, so a per-day figure is close to meaningless. Charm Regime describes whether dealers are net buying or net selling into the close purely from time-decay rehedging, which turns the vague warning about a "gamma collapse into the close" into an actual directional lean.