What is GEX?

So what is GEX?

Gamma Exposure (GEX) is a metric derived from the second derivative of an option’s value with respect to the underlying’s price. In simple terms, it represents how sensitive an option’s delta is to price movements. But more importantly, GEX is used as a proxy for how dealers (market makers) might hedge their net option positions.

Net GEX = Dealer Gamma Exposure

• Positive Gamma Exposure (green bars) implies dealers are long gamma and tend to sell into rallies and buy dips. This stabilizes price movement.
• Negative Gamma Exposure (red bars) implies dealers are short gamma and tend to buy into rallies and sell into dips. This amplifies volatility.

Since dealers aim to stay delta-neutral, they must hedge their gamma exposure using the underlying asset (e.g., SPX or ES futures). Therefore, knowing where the largest GEX concentrations exist gives clues about where the market may be pinned or volatile.

Customer vs Dealer Perspective: A Key Distinction

It’s essential to remember that tools like MenthorQ’s NetDEX and NetGEX charts are based on dealer positioning.

Here’s the rule:

• If customers are long options (positive delta), dealers are short.
• If customers are short options (negative delta), dealers are long.

Thus, when interpreting Net GEX or Net Delta, flip the position to understand dealer exposure.

Chart 1: Net GEX All Expirations for SPX

Timestamp: October 31, 2025 – 16:14 EST

This chart shows aggregated GEX positioning across all expirations for SPX options.

Key Visual Elements:

• X-axis: GEX in dollars.
• Y-axis: Strike price of SPX options.
• Green Bars: Positive gamma exposure (customers short gamma → dealers long).
• Red Bars: Negative gamma exposure (customers long gamma → dealers short).
• Yellow Line: Cumulative GEX profile (helps visualize concentration zones).
• White dashed line: Spot price at the time — 6840.
• Horizontal markers:
  
  • Call Resistance: 7000
  • Put Support: 6500
  • HVL (High Volatility Line): 6825

Interpretation:

• A thick band of green GEX is centered around the 6900–7000 strikes. This suggests dealers are long gamma in this area, so they will likely sell into strength and buy into weakness, keeping price pinned.
• A cluster of red GEX around 6450–6600 shows short gamma exposure, indicating an area where volatility could increase due to pro-cyclical dealer hedging (buying when price rises, selling when it falls).
• The spot price of 6840 sits close to the HVL, suggesting a pivotal zone where hedging behavior might flip.

This profile indicates a high potential for pinning near current spot, unless a large move pushes price into the short gamma zone below.

Chart 2: Net GEX Multi-Expiration for SPX

Timestamp: October 31, 2025 – 16:14 EST

This second chart breaks down GEX by expiration. There are four panels showing:

1. First Expiry – Nov 3, 2025 (GEX Expiring: -12.30%)
2. Next Expiry – Nov 4, 2025 (GEX Expiring: 0.74%)
3. Expiration with Highest GEX – Dec 19, 2025 (GEX Expiring: 21.14%)
4. Second Highest GEX – Nov 21, 2025 (GEX Expiring: 18.43%)

Panel 1: Nov 3 Expiration

• GEX skewed negative (red), especially between 6700 and 6850.
• Suggests that as these contracts expire, dealers may need to cover short gamma hedges, which could trigger buying pressure post-expiry.

Panel 2: Nov 4 Expiration

• Mostly neutral with small green and red areas.
• Spot price near the neutral zone → likely minimal impact from expiry flows.

Panel 3: Dec 19 Expiration

• Deep green GEX across 6800 to 7000 → indicates high dealer long gamma exposure in that area.
• This acts as a strong magnet for price: dealers will likely absorb volatility and enforce mean reversion.
• Call wall at 7000 acts as resistance.

Panel 4: Nov 21 Expiration

• Similar shape to Dec expiry but slightly lighter in GEX.
• Confirms confluence of gamma support zones between 6700 and 6900 for November series.

Why This Matters for Traders

1. Identifying Price Magnets and Barriers. Strikes with the highest positive GEX act like “gravitational pulls.” Dealers’ hedging activity tends to suppress movement and pin price. This is especially relevant around monthly OPEX (option expiration), where flows often accelerate.

2. Spotting Volatility Zones. Areas with strong negative GEX are zones of potential amplified volatility. If price enters these zones, dealer hedging may exacerbate the move—leading to breakouts or breakdowns.

3. Planning Entry/Exit Around Expiry. By observing which strikes have the largest expiring GEX, traders can prepare for hedge unwinds. A large short gamma expiry often leads to a “relief” move in the opposite direction.

Practical Uses with MenthorQ

MenthorQ’s Net GEX tools help retail and institutional traders:

• Track gamma flips across expirations.
• Identify potential “chop zones” vs “expansion zones.”
• Time trades around expiry and gamma decay windows.
• Combine Net GEX with Net Delta and Term Structure screens to understand full positioning.

For example:

• If Net GEX is heavily positive, anticipate reversion and range-bound price.
• If Net GEX is heavily negative, prepare for directional moves.

How to Trade Using GEX.

Conclusion: GEX is Dealer Reflexivity Made Visible

Understanding GEX is about more than memorizing formulas. It’s about recognizing how dealer risk management behavior creates feedback loops in markets.

MenthorQ’s tools translate institutional-level positioning into actionable retail intelligence. The October 31st GEX charts show us where markets may pin, expand, or flip, and when traders arm themselves with that data, they gain a powerful edge during critical expiry weeks.

As we head into the year-end, gamma dynamics matter more than ever. The difference between price action being trapped or unleashed often lies in these gamma profiles.

Ask QUIN to Help you Trade Using GEX.