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SPX, NDX, SPY, QQQ: Same GEX Map, Different Tape

Four underlyings, one GEX engine — why SPX looks smooth, NDX jumps farther, and QQQ/SPY can disagree with their index cousins during the same RTH window.

By GammaTape6 min read

GammaTape runs the same 0DTE GEX pipeline on SPX, NDX, SPY and QQQ. The levels mean the same thing on each tab — call wall, put wall, zero gamma, expected move — but the tape that feeds them does not. Knowing the differences keeps you from treating every chart as a clone of SPX.

Index vs ETF chain

  • SPX / NDX — cash-settled index options; strike steps are wider (often 5 pts); GEX levels map to ES / NQ.
  • SPY / QQQ — equity ETF options; 1-pt grids, different liquidity pockets, and their own 0DTE calendars.
  • Basis & timing — ETF prints can stutter or print oddly around auctions while the index path looks continuous.

That is why a QQQ path can look “blocky” for a stretch while SPX on the same afternoon is clean: thinner ETF prints and parity oddities hit the minute bars harder before filters settle them. Prefer SPX/NDX when you trade ES/NQ levels; use SPY/QQQ when you care about the ETF book itself.

Session replay across instruments
Replay trains the eye on how each instrument’s walls and path behave — not just one screenshot.

How to use the four tabs

  1. ES traders: start on SPX; glance at SPY only for ETF-specific flow.
  2. NQ traders: start on NDX; expect zero gamma and walls to move in larger point chunks than SPX.
  3. Compare OI vs Volume on the instrument you actually hedge — disagreement on QQQ does not automatically copy to NDX.
  4. When one tab looks weird, check the others before assuming the engine failed.

Switch instruments on one dashboard — same engine, four chains.

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