How market maker hedging can move ES
Options market makers (MMs) often hedge with E-mini S&P 500 futures (ES). At some strikes, their hedge orders tend to slow price down. At other strikes, they can speed price up. This guide shows how this works, and how to read it on your Bookmap chart.
In this guide
- Why MMs hedge, and what gamma does to the hedge
- Positive gamma: hedging that can slow price
- Negative gamma: hedging that can speed price up
- Why measured MM positions beat estimates from open interest
- How to read the strike profile on your ES chart
The one idea to keep
Gamma does not tell you where price will go. It tells you how price may behave when it reaches a strike.
Why MMs hedge
MMs quote options on the S&P 500 index (SPX) to buy and sell all day. They do not want to bet on direction. So they hedge: they buy or sell ES to stay neutral. When price moves, the hedge must change. Gamma tells how fast.
Where MMs own options, they are long gamma. Where they sold options, they are short gamma. The rest of this guide shows why that difference matters.
Key terms
- Option
- A contract that gives the right to buy (a call) or to sell (a put) at a set price. It expires on a set date.
- Strike
- The set price in the option contract. Each strike has its own calls and puts.
- Market maker (MM)
- A firm that quotes options to buy and sell all day, and hedges what it trades.
- Delta
- How much the value of an option changes when price moves one point. It tells the MM how much ES to hold to stay neutral.
- Gamma
- How fast delta changes when price moves. It tells the MM how much the hedge must change.
- Gamma exposure (GEX)
- The MM position at a strike × the gamma of that option.
- ES and SPX
- ES is the E-mini S&P 500 future. SPX is the S&P 500 index. The options are on SPX. You trade ES.
- 0DTE
- Zero days to expiration: options that expire on the day they trade.
Think of limit orders and stop orders
You already know two kinds of orders. Limit orders rest in the book and absorb a move. Stop orders wait, then join the move. MM hedges act in the same two ways.
MMs are long gamma. Their hedges act like resting limit orders above and below price. Push price to see what happens.
Long gamma acts like limit orders
MMs sell as price rises and buy as price falls. Their hedges absorb the move.
Short gamma acts like stop orders
MMs buy as price rises and sell as price falls. Their hedges join the move.
Why do MMs trade this way?
When MMs are long options, their delta goes up as price rises. To stay neutral, they sell ES. When price falls, they buy ES.
When MMs are short options, it is the opposite. As price rises, they must buy ES. As price falls, they must sell ES.
Gamma sets the size. High gamma means larger hedge trades for each point. MMs do not have to use limit or stop orders. The effect on price is similar.
Positive gamma: hedging can slow price
At a strike where MMs are long gamma, they sell ES as price rises and buy ES as price falls. Their hedging leans against the move.
The hedging loop
- Price rises, so MMs sell ES. The rise slows.
- Price falls, so MMs buy ES. The drop slows.
What you may see
- Price stalls or turns near the strike.
- Breakouts fail more often.
- Price stays in a range.
This is a tendency, not a rule. Large orders from other traders can break any level.
Negative gamma: hedging can speed price up
At a strike where MMs are short gamma, they buy ES as price rises and sell ES as price falls. Their hedging joins the move.
The hedging loop
- Price rises, so MMs buy ES. The rise speeds up.
- Price falls, so MMs sell ES. The drop speeds up.
What you may see
- Price moves through the strike fast.
- Breakouts follow through more often.
- Swings get larger.
No direction
Negative gamma does not mean price will fall. It can speed up a move up or a move down.
Positive and negative gamma, side by side
| Positive gamma | Negative gamma | |
|---|---|---|
| MMs at the strike | Long gamma | Short gamma |
| MM hedge | Sell rallies, buy dips | Buy rallies, sell dips |
| Acts like | Resting limit orders | Stop orders |
| Effect on price | Can slow moves | Can speed moves up |
| What you may see | Stalls, ranges, failed breakouts | Fast moves, follow-through, larger swings |
| Trader mindset | Fade the edges of the range, after price confirms | Respect breakouts, after price confirms |
| Main risk | Fading a level that stopped holding | A fast move against a large position |
The same in both cases
Wait for price to confirm. Know where you are wrong. Check the news calendar.
Naive exposure vs measured MM positions
Gamma exposure (GEX) at a strike is the MM position × the gamma of that option. Gamma comes from a model. The position must be measured. Many GEX tools guess it.
Measured: the real MM position at each strike. At the 4 shaded strikes, the naive sign is wrong. There, a strike where hedging can speed price up looks like one where it slows price, or the reverse.
Naive GEX
- Starts from open interest (OI): the number of option contracts open at each strike. OI does not show who holds them, or on which side.
- Adds a fixed rule: MMs are long every call and short every put. Customers do not always trade that way. They also buy calls in a rally, and sell puts to collect premium.
- OI updates once a day. So it misses the same-day options (0DTE, zero days to expiration) opened today.
Measured MM positions, used in this module
- Built from exchange-tagged data, which identifies all market participants, side, and size. So the MM inventory at each strike is measured, not assumed.
- The calls at a strike can show negative gamma, if MMs sold them. The puts at a strike can show positive gamma, if MMs own them. The sign comes from the real position.
- It updates every minute, so it includes the 0DTE positions opened today.
What about tools that guess the side of each trade?
Some tools read the trade price. A trade at the ask counts as a customer buy. A trade at the bid counts as a customer sell. At the mid, the side is unknown.
Multi-leg trades, such as spreads, trade at one package price. One leg alone hides who started the trade. This method is better than a fixed rule, but it is still a guess.
Read the strike profile on your ES chart
The OptionsDepth module draws one bar for each SPX strike, at its ES price. Each bar is the measured MM position at that strike × its gamma, at the price now.
Net = calls + puts. Calls and puts can each be positive or negative.
SPX strike 7,720 · ES 7,777.15
Positive gamma: MMs are long gamma at this strike.
Size: +$2.45 billion per 1% move. To stay hedged, MMs would need to trade about 82 ES contracts for each point ES moves, against the move.
If price gets here, MM hedging tends to slow the move.
Select another bar to read it.
How to read it
- Look for big bars near price. A bar is large when the MM position is large, or when the strike is near the price. Gamma is highest there.
- Blue near price: moves tend to slow there. Orange near price: moves can speed up there.
- Bars change as price moves and as time passes. The module updates every minute, with a short delay. That is enough: you are not scalping the tape, you are trading the mechanics.
From SPX to ES
Strike labels show SPX strikes. The module places each bar at its ES price, with the live basis: ES = SPX + basis. Example: SPX 7,720 + 57.15 = ES 7,777.15. You do not need to convert.
Practice: two scenarios
Each scenario shows the strike profile on an ES chart. Choose the best next step. Then watch one possible outcome.
Price rises into a large blue bar
ES rises toward the largest blue bar, at SPX 7,720 (shaded). MMs are long gamma there. Price has not reached it yet.
What is the best next step?
Price falls out of the blue zone
ES just fell below the lowest blue bar, at SPX 7,710 (ES 7,767). Just below, the profile shows orange bars (shaded): MMs are short gamma there.
What is the best next step?
What the profile cannot tell you
Where price will go
Gamma is reactive. It shows how hedges may respond if price moves, not where price goes.
Which MM trades are hedges
The data measures MM positions and trades. No data can show which trades are hedges. MMs can also hedge in other products.
The exact gamma
The position is measured. Gamma is calculated with a model.
What other traders will do
Large orders, news, or a data release can overwhelm any strike.
What the profile will become
Every bar changes as price moves, as time passes, and as options trade. A profile is a snapshot.
Takeaways
Gamma does not tell you where price must go. It tells you how price may behave at a strike.
A simple routine
- Find the big bars near price.
- Read the sign: blue can slow moves, orange can speed them up.
- Check the news calendar.
- Wait for price to confirm at the strike.
- Set your stop and your maximum loss before you trade.
Check what you learned
Ten questions. After each answer, you see a short explanation.
Question 1 of 10
What does gamma exposure at a strike help you judge?
Education only. Not trading advice. All charts use illustrative data, not live market data.