The GEX matrix on SPX Slayer is a strike-by-expiry grid that maps where dealer gamma exposure concentrates across the entire SPX options chain. It is the positioning backbone of the dashboard — every graded play factors in where the walls sit and which regime price is trading in. Here is how to read it cell by cell.
The grid: strikes x expirations
The matrix is a heatmap table. Each row is a strike price. Each column is an expiration date — the leftmost column is the 0DTE (same-day) expiry, and subsequent columns move out to weeklies and monthlies. Each cell contains a signed dollar value representing the net gamma exposure at that specific strike-expiry intersection.
Positive cells (green) mean dealers are net long gamma — hedging dampens moves. Negative cells (red) mean short gamma — hedging amplifies. The diverging color scale runs from deep red through gray (near-zero) to deep green, so the visual pattern tells the story before you read a single number.
The spot row highlight
The row at the current SPX price is highlighted. Everything above is overhead resistance context; everything below is downside support context. As SPX moves, the highlight follows.
King nodes
Certain cells carry a star marker — these are King nodes, the single largest absolute gamma concentration in their column (expiry). A King node at the 5,550 strike in the 0DTE column means that strike carries more gamma for today's expiry than any other. King nodes often coincide with the call wall or put wall, but not always — the wall is the largest concentration across all expirations, while a King node is the largest within a single expiry.
Column max +/- (gamma walls)
Each column marks the column maximum positive and column maximum negative values — that expiry's local gamma walls. Aggregated across all columns, these produce the overall call wall and put wall. Column-level walls reveal whether a single expiry (say, this Friday's monthly) is driving the aggregate wall or whether it is spread across many.
GEX vs VEX lens toggle
A toggle at the top of the matrix switches between two views:
GEX lens — the default. Shows gamma exposure per cell. This is the primary positioning read: where dealers must buy and sell as price moves, and how aggressively. Use this for regime reads, wall identification, and flip-level awareness.
VEX lens — shows vanna exposure per cell — how dealer delta changes as implied volatility shifts. Critical on days when IV is moving sharply. See Thermal's Four Lenses.
Gamma flip and the 0DTE column
The gamma flip is marked directly on the matrix. For the 0DTE column, the flip is especially important because same-day gamma is enormous and fast-decaying. The 0DTE flip can differ from the full-chain flip when longer-dated expirations carry gamma at different strikes — when they diverge, expect choppy price behavior.
The net exposure summary at the bottom of the 0DTE column shows aggregate gamma for all same-day contracts — the quick-glance answer to "is today's session stabilized or amplified by 0DTE positioning?"
Convergence and divergence between walls and price
The matrix's real power is pattern recognition. When the call wall, put wall, and flip converge on a narrow range around current price, expect a grinding, range-bound session — all three forces are acting as magnets and barriers in a tight zone. When they diverge — flip far below price, call wall far above, put wall far below — the range is wide open, and price has room to trend before hitting a mechanical barrier.
Watch for wall migration during the session. If the call wall at 5,550 weakens (its cell value shrinks) while a new gamma cluster builds at 5,570, the ceiling is shifting higher. The matrix updates in real time, so checking it mid-session — not just at the open — is how you catch repositioning before the chart shows it.
Cross-referencing with the play engine
The gate logic in the center column already reads the regime, walls, and flip from this grid. But seeing the raw matrix lets you understand why a play graded the way it did — a B near a thick wall makes sense; an A in open space between walls makes sense too.
For the full Thermal heatmap with profile view and overlays, see How to Read Thermal Heatmaps. Get access →
BlackOut provides educational tools and market analysis only and does not provide investment advice. Options trading involves substantial risk and is not suitable for every investor.
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Reading the SPX Slayer GEX Matrix in action — the Thermal dealer-positioning heatmap on the BlackOut desk. Open it live →
Originally published on BlackOut Trades — live dealer gamma, 0DTE options flow, and A–F graded SPX setups. Try the free Gamma Snapshot tool →
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