Read positioning like a map.

Every option a dealer holds forces them to hedge in the underlying as price moves. Gamma exposure measures how much, and in which direction. Aggregated across the chain it produces a small set of price levels that tend to act as magnets, supports, resistances and tipping points during the session.

GammaTape computes these levels for SPX, NDX, QQQ and SPY on 0DTE (same-day expiry) options, updates them in near real time from a real-time options data feed, and draws them directly on the price chart in index points — so there is nothing to convert.

The control bar above the chart drives everything:

Chart · GEX / Convexity

Switch the level set drawn on the price chart. GEX shows the call/put walls and zero gamma; Convexity shows the major long/short gamma anchors. Both respect the OI/Volume weight.

Weight · OI / Volume / OI+Vol

Weight every level by open interest (the standing book), the day's traded volume (intraday flow), or OI+Vol — the confluence walls where both books agree (call/put in GEX, long/short Γ in Convexity). See weighting below.

Levels menu

One menu groups every line — gamma walls, regime, reference and display (trail) — plus an Experimental section for the skew-adjusted dealer-sign levels. The count shows how many are active.

Orderflow · Off / DEX / GEX / Conv

Open a histogram pane under the chart showing per-minute flow into delta, gamma-by-type, or convexity. Spikes flag where positioning shifts.

Layout

One chart, two columns, two rows, or a 2×2 grid of instruments (live).

The right panel shows the GEX profile by strike (the distribution of exposure around spot) and the Key levels list with each level's distance from spot, strength, and the options metrics block.

Per contract, dollar gamma per 1% move is gamma × weight × 100 × spot² × 0.01, where weight is open interest or traded volume. Under the standard convention dealers are long calls and short puts, so calls contribute positive gamma and puts negative.

Summed across the chain you get Net GEX. When it is positive, dealers hedge against the move (sell rallies, buy dips) and price tends to mean-revert — ranges, low realised volatility. When it is negative, they hedge with the move (sell weakness, buy strength) and moves accelerate — trends, vol expansion. The per-strike version is what the profile bars show.

A wall is the strike carrying the most gamma on one side of the chain. The Call Wall sits above price and tends to cap rallies; the Put Wall sits below and tends to support. Each wall row in Key levels shows its strength (share of that side's gamma sitting on the strike), an optional zone when neighbouring strikes cluster into one wall, and which measures confirm it.

When the Call Wall and Put Wall land on the same strike, the chart shows a gamma-compression marker — a tight, heavily-pinned setup.

Zero gamma (the gamma flip) is the price level where net dealer gamma crosses zero. Above it the market is usually in the stabilising, mean-reverting regime; below it, the accelerating one — the single most useful regime read of the day.

It is the true repriced flip nearest spot, computed independently for OI and Volume (each shows its own), and gently smoothed so the line is clean. On a balanced book it sits near price; on a one-sided book it sits where the book actually flips, which can be further away — that distance is itself the signal.

Convexity reads the same book through the lens of who holds the gamma. Switch the chart to Convexity to replace the walls with two anchors:

Major Long Γ

Strike where dealers are longest gamma — the strongest pin, where price tends to get held.

Major Short Γ

Strike where dealers are shortest gamma — where hedging amplifies moves and volatility expands.

Convexity respects the OI/Volume weight: OI shows the Net Gamma Majors of the standing book, Volume the majors of the day's directional flow. The profile pane and a Net Convexity sub-chart follow the same weight (cyan for long gamma, fuchsia for short).

The Orderflow selector opens a per-minute histogram under the chart. Each bar is the net flow over that minute; large spikes mark moments where positioning shifts and can precede a continuation or a reversal.

DEX orderflow

Net delta flow — bullish (right) vs bearish (left). Tracks directional pressure.

GEX orderflow

Call gamma flow minus put gamma flow — which option type is being worked.

Convexity orderflow

Net option buying vs selling, gamma-weighted — positive when participants pay up for convexity (expecting more volatility).

The Key levels footer carries the headline exposures for the whole chain:

DEX

Delta exposure — the capital required to hedge the book's directional risk (calls positive, puts negative).

−Vanna Ex

How exposure shifts as implied volatility falls into expiry. It turns amber, then red, at the levels where it historically starts to drive sharp intraday reversals.

Charm /h

Delta decay per hour — hedging pressure created purely by time passing, which clusters into the close.

ATM IV

At-the-money implied volatility — the market's near-term volatility read.

Max Pain

The strike that minimises total option-holder payout at expiry — a soft end-of-day magnet.

Beyond the gamma structure, a few classic intraday references are drawn as fixed horizontal lines — they pair powerfully with the walls (a wall that lines up with a reference level is a strong level):

Expected Move (±1σ / ±2σ)

The implied range priced into today's options, fixed at the open. Price closes within ±1σ most days; in a positive-gamma regime the edges are fade zones, a clean break that holds signals a trend day toward ±2σ.

Abs Gamma

The single strike with the most total gamma (any side) — the strongest magnet of the day.

Day levels (PDH/PDL/PDC)

Prior session high, low and close — the reference points every intraday trader watches.

Opening range

High and low of the first 30 minutes (the Initial Balance) — breakouts and rejections of it set the day's tone.

Open interest (OI) is the standing book — every contract still open. It moves slowly and gives the structural map of the session: use it for the morning levels and the zero-gamma regime.

Volume weights by the day's traded flow, aggressor-classified so the sign reflects whether dealers are being pushed long or short. It is faster and shows which levels are active right now — use it intraday and for convexity.

OI+Vol — the confluence walls: the strike nearest spot where the OI book and the day's volume BOTH carry strong gamma on the same side. They are rarer but higher-conviction than either wall alone — the level both the structural map and live flow point at. In GEX it marks the call/put confluence (teal / pink); in Convexity it marks where both books are net long / short gamma. They trail like the other walls.

Skew (beta) — an experimental refinement of the OI book. Instead of assuming dealers are long every call and short every put, it reads each contract's implied vol against the strike's own smile: a richly-bid option means customers were buying it (dealers shorter there), a cheap one means they were selling (dealers longer). It corrects only the sign-sensitive levels — the skew zero gamma and the skew long/short Γ majors — leaving the walls untouched. In our research it was the best regime classifier of the models tested; enable it under Levels → Experimental.

Switch to Replay to scrub any past session. The slider runs the full day; play at 1×, 2×, 4× or 8× and watch the walls, zero gamma and profile move with price. The level trails reveal how positioning built up into the moves that mattered.

The Heatmap tab plots every wall's strike over the whole session (time across, strike up). Each minute paints a faint mark; marks stack, so a strike a wall rested on glows bright while one that flickered stays dim.

Use it to separate the real magnet from the noise: the brightest, longest band is the sticky wall that actually held — far more reliable than the latest snapshot. It follows the OI/Volume weight and updates live and in replay.

Source

A real-time options data provider supplies the option chains and full intraday history. GammaTape computes every level itself — nothing is taken on trust.

Scope

0DTE (same-day expiry) options on SPX, NDX, QQQ and SPY, each computed independently from its own chain.

Spot

The index price is derived from the option chain via put-call parity — no separate price feed required.

Greeks

Implied volatility and gamma (plus delta, vanna and charm) are computed from mid quotes, so levels stay consistent between live and replay.