Gamma is the most important greek and the easiest to feel. It's the force that builds walls, floors and trapdoors, and it decides the single biggest question of any session: is today a pinning day or a trending day? Let's build it from nothing.
Forget the textbook. Here's the only definition you need: gamma is how quickly a dealer's hedge has to change as price moves. When dealers hold a lot of gamma at a strike, they're forced to trade futures aggressively around that price — and that forced trading is what you see as support and resistance.
Every gamma board is one of two characters. Knowing which one you're in tells you whether to fade moves or follow them. Get this right and you're ahead of most traders.
Dealers trade against price. Rallies get sold, dips get bought. Result: mean reversion. Fade the extremes back toward the middle. This is where ceilings, floors and magnets live.
Dealers trade with price. Selling begets selling, rallies squeeze. Result: trends and breakouts. Follow, never fade. This is where trapdoors and vol zones live.
| If the board is… | Dealers… | Price tends to… | Your default |
|---|---|---|---|
| Positive gamma | trade against the move | pin, range, mean-revert | Fade extremes to walls |
| Negative gamma | trade with the move | trend, break out, gap-and-go | Follow momentum |
The two regimes meet at one price: the gamma flip. Above it the board is positive (stabilizing); below it the board is negative (accelerating). It's the single most important line on your chart because it tells you which playbook to run.
Zoom out from a single line to the shape of the whole board. Where the gamma is stacked — ahead of price or behind it, positive or negative — sorts every day into one of four scenarios. This is your morning classification.
| Scenario | Structure | Day type | How to trade it |
|---|---|---|---|
| Forward Positive Ramp | Large +γ stacked ahead in the direction price is heading | Grind / Range | Fade extensions — dealers absorb the move. Mean reversion. |
| Backward Positive Ramp | +γ is behind price; ahead is thin or negative | Reversal / Chop | Price can move fast once the last +γ clears. Watch for a breakout. |
| Forward Negative Slide | −γ stacked ahead, in the direction of travel | Trend | Follow, never fade. Dealers chase. The most important setup. |
| Backward Negative Slide | −γ was behind; ahead is +γ or neutral | Grind (recovery) | Worst of the move is likely done. Expect a grind recovery. |
Every board resolves to one Day Type — the single label your pipeline prints at the top of the read, colour-coded so you can size the day at a glance:
Gamma produces five of your levels directly — the walls, pins and cliffs — plus the one line that governs them all. Here's the map from greek to level:
Positive gamma above you = a cap. Positive below = a cushion. Negative next to you = a cliff edge — a trapdoor below, a squeeze above. That's the entire translation. Go see each one in depth on the Levels page.