Article

Why Zero Gamma Can Jump Mid-Session (Especially on NDX)

The orange zero-gamma line is a crossing in a living GEX profile — not a VWAP. Learn when sudden moves are noise, when they mark a real regime shift, and how to read them on NDX vs SPX.

By GammaTape7 min read

Candlestick chart — zero gamma is a regime line that can relocate when the book reshapes

Zero gamma is the price where net dealer gamma flips sign. On a calm SPX afternoon it drifts. On NDX — or any session where volume rewrites the ladder — it can relocate in a step. That step feels like a glitch; often it is the math catching a real reshape of the book.

What “moves” zero gamma

  • New 0DTE volume concentrating on one side of the prior flip.
  • OI updates that shift which strikes dominate the signed sum.
  • A briefly one-sided volume profile (no clean crossing) that then reappears a strike cluster away.
  • Index vs ETF: NDX’s wider strike grid and thinner wings make crossings jump farther in points than SPX or QQQ.
Scrub a session and watch zero gamma drift relative to spot and the walls.

Noise vs signal

  1. Spike and snap-back within a few minutes → treat as profile noise; wait for the line to settle.
  2. Jump that holds while walls migrate with it → regime map updated; re-orient spot vs the new flip.
  3. Disagree between OI flip and Volume flip → structural book vs today’s flow; prefer OI for the stable divider, Volume for aggression.

Practical read for NQ traders

Map NDX zero gamma onto NQ the same way you map walls. A sudden relocation does not mean “buy/sell the spike” — it means the dampen/amplify boundary moved. Combine it with call/put walls and whether price accepted above or below the new flip before changing how you size mean-revert vs trend behaviour.

Watch zero gamma live on NDX and SPX.

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