When dealers are net long gamma, they hedge against the move — selling strength and buying weakness — which tends to pin price and compress range. When they're net short gamma, they hedge with the move, which can amplify trends and expand range.
The gamma flip
The gamma flip is the price where total dealer gamma crosses zero. Above it, the book is typically long-gamma (pin / mean-revert); below it, short-gamma (expansion). It's the single most useful line on the chart.
Walls
A wall is a strike where dealer gamma concentrates. We classify them by
relative size — MEGA_WALL, WALL, SHELF — and by hardness (how much delta
sits with the gamma). Hard walls tend to act like magnets and brakes.
Reading it
- Spot above the gamma flip → expect grind / mean-reversion.
- Spot below the gamma flip → expect larger, trendier moves.
- Air pockets between walls → fast travel zones.
None of this is a signal — it's context for how the tape is likely to behave.