GEX
Updated Aug 25, 2026
GEX is short for gamma exposure. It is an estimate of how much option gamma market makers are holding across the SPX option chain, and where that gamma is concentrated. Whispertrades calculates it from SPX open interest and publishes a set of levels once a day, before the market opens, on the GEX page.
You do not have to trade gamma to use these levels. They are simply price levels the market often behaves differently around, and your bots and backtests can filter on them.
The levels
Call Wall
The strike above the current price with the largest concentration of call gamma. Dealers hedging that gamma tend to sell into rallies as price approaches it, so the call wall often behaves as resistance and as a place where upward moves slow down.
Put Wall
The strike below the current price with the largest concentration of put gamma. The same hedging works in the other direction, so the put wall often behaves as support.
Flip Level
The price at which total gamma exposure crosses from positive to negative. It is the most consequential of the three, because it separates two different market characters rather than marking a single price.
Positive and negative GEX
Total GEX is the sum of dealer gamma across every strike and expiration, and its sign describes how hedging flows are likely to behave.
Positive GEX | Negative GEX | |
|---|---|---|
Where price is | Above the flip level | Below the flip level |
Hedging flows | Sell into strength, buy into weakness | Sell into weakness, buy into strength |
Typical character | Moves get dampened, ranges hold better | Moves get amplified, trends and gaps extend |
This is a tendency, not a rule. Plenty of negative GEX days are quiet and plenty of positive GEX days are not.
GEX levels are calculated once a day from open interest before the open. They describe where positioning sat that morning, and they do not update as the session moves. Treat them as context for the day, not as a live indicator.
Where you can use them
Strike selection. Anchor a strike to the call wall, flip level or put wall, with an optional offset percent. See Strike Selection.
Entry filters. Require a minimum or maximum total GEX, or a minimum or maximum distance from any of the three levels. See Entry Filters.
Exit conditions. Exit when SPX crosses a level, with an optional offset. See GEX exits.
Backtests. All of the above, over the full backtest history. Whispertrades keeps a complete historical record of these levels, so a GEX filter behaves the same in a backtest as it does live.
Offsets
Every GEX setting takes an optional offset percent so you do not have to sit exactly on a level. If the call wall is at 7000 and you want to work 0.5% above it, use an offset of 0.5% and your level becomes roughly 7035. Negative offsets move you below the level.
Availability
GEX levels are SPX only. Every GEX field, in both bots and backtests, is available to SPXW positions and hidden everywhere else. The levels are calculated once per day from that morning's open interest and do not move intraday.