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Key Takeaways
- The gamma flip is the underlying price where aggregate GEX crosses zero and changes sign.
- Positive-gamma hedging sells rallies and buys declines; negative-gamma hedging buys rallies and sells declines.
- Read the aggregate curve to identify the sign on each side of the crossing.
- The strike profile maps concentrations, while the aggregate spot-price curve locates the flip.
- Connect the flip with the call wall, put wall, options flow, and technical structure to frame the trade.
What is the gamma flip?
The gamma flip is the underlying price where aggregate dealer gamma exposure crosses zero and changes sign. It connects a price level with a change in the direction of delta-hedging pressure. Positive-gamma hedging sells rallies and buys declines, while negative-gamma hedging buys rallies and sells declines, and the aggregate curve shows which sign sits on each side of the crossing.
How is the gamma flip calculated?
A strike profile groups exposure by option strike. It shows where positioning is concentrated. The gamma flip comes from a different calculation: reprice the option portfolio across hypothetical underlying prices and sum the signed GEX at each price. The zero crossing of that aggregate curve gives the flip.
Plot the calculated flip alongside the strike profile to connect the regime boundary with the major concentrations. Keep the call wall and put wall visible on the same price map.
Formula
Gamma flip = underlying price S where aggregate dealer GEX(S) = 0- GEX(S) sums each contract gamma scaled by contract multiplier, open interest or positions, and a chosen move size across all strikes and expirations at hypothetical price S.
- The flip is the S at which that sum changes sign. The dealer-positioning convention decides which side reads positive, and the positions themselves decide where the crossing sits.
- Because gamma and delta change with price, volatility, and time, the level is recalculated continuously rather than fixed.
Gamma flip example
SPX trades at 5,000, a gamma model places the flip at 4,940, and 15,000 contracts are open at strikes near the flip. Aggregate gamma is positive above that level and negative below it.
- Spot 5,000 sits 60 points above the modeled flip at 4,940, so the model reads the current regime as positive gamma.
- A decline to 4,930 would cross below 4,940, moving aggregate GEX from positive to negative in the model.
- Price the cluster as SPX options, which carry a $100-per-index-point multiplier: each full unit of delta the 15,000 contracts near the flip gain or lose moves dealer exposure by $1.5 million per index point. Dealers size the hedge from that change in delta and the instrument they hedge with, futures or a stock basket.
Above 4,940 the modeled dealer book is long gamma, so its hedging buys dips and sells rallies. A sustained break below 4,940 flips the book short gamma, and its hedging sells into the decline. Recalculate the flip as positions and volatility change, since the level moves with them.
Read the signs from the curve on every chain you trade; this one runs positive above the crossing and negative below.
How traders use the gamma flip
Start with the current aggregate sign. Next, measure spot’s distance from the flip and the nearby walls. Read options flow around those levels and look for technical confirmation as price reaches the zone.
For a position already open, compare the next reference level with the trade’s breakeven and payoff. For a new setup, use the options profit calculator to compare strike placement and expiration before choosing the structure.
Why the gamma flip moves
Positions, expirations, volatility, and price inputs change the aggregate curve. Recalculate the map as those inputs change and compare the resulting levels with the developing price structure.
The gamma flip locates a regime transition and the strike profile identifies concentrations; both shift as those inputs change.
Limitations of the gamma flip
- Know the positioning convention behind the map. Reversing every assumed position sign keeps the crossing in place but swaps which side is positive gamma, and changing the relative positions moves the crossing itself.
- Count the crossings. With none, the whole range sits in one regime; with several, mark each one and watch the nearest to spot.
- Refresh the map each morning. Open interest updates once per trading day, so positions opened today enter the curve at the next update, and the dealer side of each contract comes from the model’s convention.
- Let flow set the direction. Crossing the flip changes how hedging responds, and when flow or news is strong enough, price runs through the level in either regime.
Bottom line
Above the gamma flip, hedging leans against moves; below it, hedging chases them, so the flip is where the tape changes character. Measure spot’s distance to it, read it with the walls and the strike profile, and recalculate it as positions, expirations, and volatility change.
Clear answers
Frequently Asked Questions
Sources and Further Reading
- Cboe: SPX Options Contract Specifications
- Cboe: Market-maker gamma analysis and 0DTE market impact
- OIC: Gamma
- OIC: Volatility & the Greeks
How entries are sourced, calculated and updated: editorial methodology.