NDX gamma exposure: flip, call wall, put wall

Dealer gamma by strike for Nasdaq-100 index, from the option chain itself: two books, the level where net gamma changes sign, and the two strikes that carry the most. Expiries out to 120 days.

data as of 2026-11-02 16:15:00 ET · not updating right now · replay NDX in the terminal
Spot
28084
from put-call parity
Zero gamma flip
28437
1.3% above spot
Call wall
28550
1.7% above spot
Put wall
28000
0.3% below spot
Net gamma, volume
-$986M
per 1% move
Net gamma, OI
-$1.94B
per 1% move
Price sits below the flip at 28437: on this book dealer hedging adds to a move rather than leaning against it.
The session, 2026-10-20 priceflipcall wallput wall
29875290002957329550 net gamma, volume book09:3010:3011:3012:3013:3014:3015:30
day11-0210-3010-2910-2810-2710-2610-2310-2210-2110-2010-1910-16 82 points · volume book · levels drawn as they stood
Strikes through the day levelchange since the open absorbs a movefeeds itprice
296402963029625296202961029600295902958029575295702956029550295402953029525295202951029500294902948029475294702946009:3010:3011:3012:3013:3014:3015:30
Gamma by strike, two books on one axis
OPEN INTEREST · last close
STRIKE
VOLUME · today
28210
28200
28180
28175
28170
28160
28150
28140
28130
28125
28120
28110
28100
28090
28080
spot
28075
28070
28060
28050
28040
28030
28025
28020
28010
28000
put wall
27990
27980
27975
27970
27960
27950
By expiry, volume book
expiryflipcallputnet
2026-11-03283382855028100-$528M
2026-11-04287322832526800-$108M
2026-11-05n/a2877528530-$122M
2026-11-06283352870027700-$38M
2026-11-09285782900027000-$34M
2026-11-10295042855027700-$12M
How far to trust this bookB

an index or an ETF; the convention holds, the tape is thinner.

Prints a second, regular session0.62
Strikes where the two books agree on the sign50%
Contracts traded today, expiries shown32,528

What this page assumes

  • Calls count as dealer-long gamma and puts as dealer-short. That is a convention, not a measurement: open interest does not say who holds a contract.
  • The volume book signs today's traded contracts. The open-interest book uses positions as of the last close and does not move inside the day.
  • Spot is derived from the option quotes by put-call parity, so it can sit a few cents from the last trade in the underlying.
  • Two roots of the index, the daily and the monthly, are added together on the dates they share.
  • Every figure is dollars of dealer delta per 1% move in NDX, the unit that compares across symbols.
  • There is no tape-signed book on this page. That book exists only where a live engine runs.

Questions

What does it mean that NDX is below its flip?

Net dealer gamma on this book is negative, so hedging flows tend to add to a move. It says nothing about direction.

Why are there two books?

Open interest is positioning as it stood at the last close. Volume is what traded today. When they disagree, that split is the reading.

Is this a trading signal?

No. We tested wall touches and flip crosses on SPX across more than a thousand sessions and found no edge that survives costs. These are measurements of where hedging concentrates.

How is this different from the SPX terminal?

SPX runs on a live engine: every second, with a third book signed print by print from the trade tape. This page is rebuilt from chain snapshots and carries the two conventional books only.