What is Gamma Exposure (GEX)?
Gamma exposure (GEX) measures how much delta hedging option dealers and market makers must do as Bank Nifty moves. Every option has gamma — the rate at which its delta changes with the underlying. When you add up the gamma of every open contract, weighted by open interest, you get a map of where hedging flows will be strongest. Those flows are large enough to shape intraday behaviour: they can pin the index to a strike, dampen a move, or pour fuel on one.
The concept was formalised by SqueezeMetrics in their original GEX white paper (2017), which showed that aggregate dealer gamma explains a meaningful share of S&P 500 behaviour. Later work — including ALpresi Research — found that the daily change in GEX explains same-day returns roughly three times better than the level itself, which is why this dashboard tracks ΔGEX momentum as a first-class number.
How to read the Bank Nifty GEX dashboard
The bar chart shows net GEX per strike: green bars are strikes where dealer hedging stabilises price, rose bars where it amplifies moves. Four levels matter most:
- Net GEX and regime — the sign and size of total dealer gamma. Long gamma compresses ranges; short gamma expands them.
- Gamma flip — the index level where net dealer gamma changes sign. Crossing it often changes the day's character from mean-reverting to trending.
- Call wall — the biggest call-gamma strike above spot; a common resistance zone and expiry-pinning magnet.
- Put wall — the biggest put-gamma strike below spot; a common support zone. A close beyond a wall can accelerate as hedges unwind.
The chart below the profile shows how net GEX evolved through the session — watching it flip sign intraday is often more useful than any single reading.
Dealer gamma regimes at a glance
| Regime | Dealer hedging | Typical behaviour |
|---|---|---|
| Strong long gamma | Sell rallies, buy dips | Tight ranges, pinning near big strikes |
| Long gamma | Counter-trend | Mean reversion favoured |
| Flip zone | Unstable | Whipsaw-prone, regime can change mid-session |
| Short gamma | Chases price | Ranges expand, breakouts follow through |
| Strong short gamma | Amplifies every move | Trending, high-volatility days, squeeze risk |
How we calculate Bank Nifty GEX
For each strike and expiry we solve Black-Scholes implied volatility from live option prices, compute gamma, and aggregate: GEX = Γ × OI × Spot² × 1%, with calls positive and puts negative (dealers assumed net long calls, net short puts). Values are expressed in ₹ crore of delta-hedge notional per 1% index move. The gamma flip is found by re-pricing the entire chain across a grid of hypothetical spot levels and interpolating where net GEX crosses zero.
GEX numbers differ across websites — sometimes by large factors. The usual reasons: open interest counted in units vs contracts (a fixed multiple of lot size), nearest-expiry vs all-expiry scope, and different gamma inputs. Levels that don't depend on scale — the gamma flip, the call and put walls, and the regime — are directly comparable across sources, and those are what we recommend trading from.
Methodology last reviewed July 2026 · Symbols covered: Nifty, Bank Nifty, Sensex, FinNifty, Midcap Nifty, Bankex.