Gamma measures how option delta changes as the underlying index moves. This chart aggregates reported gamma and outstanding open interest across full-size NDX and NDXP options. It assumes calls contribute positively and puts negatively. Open interest does not reveal actual dealer ownership: the result is a positioning proxy, rather than observed dealer hedging, cash flow or a forecast.

One consistent model. Both the historical daily estimate and the latest strike profiles use Σ signed gamma × open interest × 100 × NDX spot, in dollars of hedge-notional change per index point. All active expiries in the source chain are included. The 100-dollar multiplier and NDX/NDXP settlement conventions follow Nasdaq’s contract specifications. QQQ, XND and SPX contracts are excluded.

The default units are $ billions per NDX point. For the alternative, multiply by snapshot NDX spot × 0.01 to obtain dollars per 1% move, then divide by one billion. A one-point NDX move is a different percentage move from one SPX point. Neither conversion makes these figures identical to another provider’s proprietary dealer-position model. Gamma is a local approximation and changes as prices and time change.

The lower plot aggregates the entire active chain. The orange dotted average requires five consecutive valid daily readings. The rank compares with the preceding 252 sessions only when all are available. Missing values are never treated as zero, connected across a gap, or interpolated.

Daily GEX history starts on 27 July 2026, using original archived Cboe delayed NDX option-chain responses. For each session, the latest valid snapshot in the final 30 minutes before the exchange close is selected. These are afternoon observations, generally around 15:54 New York, rather than exact closing-option books. Source timestamps, NDX spot, filenames and SHA-256 hashes are provided with the download. Early-close days use the earlier close. A session without a qualifying archive remains blank.

The teal on-canvas magnitude profile extends left from the price panel’s right edge. The third canvas shows positive net GEX in green left of zero and negative net GEX in red right of zero. Both sum calls minus puts into the same bins, using the same expiry filter, units and visible price range; the teal overlay then takes the absolute value of each net bin. The default is 10-point bins, with native strikes, presets, Automatic and custom widths available. NDX’s available strike spacing limits the finest detail: smaller bins never invent extra strikes. Your bin setting is saved separately from the SPX page.

Changing granularity or profile expiries does not change the historical aggregate. Both profile widths scale to the largest visible magnitude. Their timestamp stays fixed when you hover over old prices; an aggregate daily number cannot reconstruct old profiles. Same-day AM-settled NDX contracts expire at 09:30 New York; PM-settled NDXP contracts expire at the scheduled session close, including early closes. Post-close profiles can therefore differ from that day’s pre-close archive, particularly around expiry. Open interest generally describes prior-session positions and the feed is delayed.

Nasdaq-100 prices use Yahoo Finance daily ^NDX OHLC. Prices begin in October 1985. Traditional green/red candles cover October 2024 onward. A view starting earlier switches to the white daily closing-price line; returning to the covered range restores candles. Completed cash sessions only are admitted after a 20-minute publication allowance. Sessions are equally spaced, removing weekend, holiday and overnight gaps, while retaining actual OHLC and price gaps. Candle bodies fill their session width. Right-hand space keeps candles clear of the teal profile.

Automatic refreshes run on U.S. weekdays: hourly during the daytime, with additional captures in the final half-hour of normal and early-close sessions. The page checks saved data every 15 minutes and when you return to it. Original chain and price responses are archived. Invalid, stale, regressed or truncated responses preserve the last valid snapshot and show a warning. Price and profile feeds are checked independently. Validated older prices are retained if an upstream response drops a session. Missing future observations remain possible if the source is unavailable; they are disclosed rather than estimated.

This page uses the same layout as the SPX Net GEX page, but its historical GEX is calculated from the NDX/NDXP archives. SPX history uses SqueezeMetrics’ published series. Differences in the option universe, dealer assumptions, source timing and index level affect comparisons between them.