MK.TRADES · LEARN
Quant Field Guide · No. 03

Gamma Exposure

Every day, the banks on the other side of the options market are forced to buy and sell the underlying — not because they have a view, but because their risk makes them. Gamma exposure is the map of that forced flow. It tells you when the market has brakes, and when it has none.

γOne number decides the whole character of the tape: are you above the flip, or below it?
1What gamma exposure is

Somebody has to hedge

Five words first — everything below is built from these
STRIKE
A fixed price level where option contracts exist. The options market is organised into these rungs — 4010, 4021, 4032 and so on. Every level in this guide sits at a strike.
SPOT
Simply where the market is trading right now. On every screen in this guide it's drawn as a horizontal line, so you can instantly see which levels are above price and which are below.
EXPIRY
The date a batch of option contracts dies. Options are grouped into expiries, and when one passes, every contract in it — and every effect it had on price — disappears.
DEALER
The professional firm on the other side of your option trade. A bank or market maker. They aren't betting on direction — they're managing risk, and that difference is what this whole guide rests on.
OPEN INTEREST
How many option contracts currently exist at a strike. Think of it as inventory parked at that price level.

When you buy an option, someone sold it to you. That someone is usually a dealer — a market maker whose business is providing the contract, not betting on direction. They don't want the directional risk they just took on, so they hedge it by trading the underlying.

Here's the part that matters: that hedge is not set-and-forget. As price moves, the amount of underlying they need shifts, so they must keep re-trading. They are forced buyers and sellers, every single day, in size, and entirely without a view on where price should go.

Gamma is the rate at which that hedging requirement changes. Gamma exposure (GEX) is that rate, multiplied out across every open contract in the market — the total size of the forced flow waiting at each price level.

OPEN INTEREST how many contracts sit at this strike × GAMMA how much hedging each one forces = GAMMA EXPOSURE the size of the forced flow at this price level signed: + or − GEX is open interest, weighted by how much hedging each contract actually forces.
The OPEN INTEREST tab shows you the raw contract counts. The GEX PROFILE tab shows you the same book after weighting — which is why the two screens rhyme, but never look identical. Raw inventory vs. inventory that actually moves the market.
The OPEN INTEREST tab as a mirror histogram, put open interest fanning left and call open interest fanning right, with the call wall marked
This is the raw ingredient: the OPEN INTEREST tab, puts fanning left and calls fanning right. The tall call stack at 4141 is the same wall you'll see dominate the gamma profile. One caution that matters later — open interest counts contracts, and every contract is one buyer and one seller, so this screen can never tell you who is long and who is short.
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No conspiracy required

Nobody sits in a room deciding to walk price to a level. Dealers hedge mechanically, because their risk limits require it. The price effects you're about to learn are a byproduct of that plumbing — not anyone's plan. That's exactly why it's reliable enough to trade around.

2The two regimes

Brakes, or no brakes

Everything in this guide reduces to one question. Dealers are either long gamma or short gamma — and the answer completely inverts how the market behaves.

POSITIVE γ · dealers LONG gamma hedging OPPOSES the move GREEN STRIKE BUYS SELLS BRAKE · swings shrink, price PINS it does not bounce off — it gets stuck on NEGATIVE γ · dealers SHORT gamma hedging JOINS the move RED STRIKE BUYS SELLS EITHER WAY ACCELERANT no braking side — it is a speed zone, not a level
The white line is price. Left: every swing meets opposing dealer flow, so the swings shrink and price settles onto the level — a pin, not a bounce. Right: dealer flow joins the move instead, so price leaves the level and steepens — and it does that in either direction, which is the part almost everyone gets wrong.
POSITIVE γ
spot above the flip

Dealers are net stabilisers. Every rally meets selling, every dip meets buying.

  • Volatility compresses
  • Ranges hold, edges get respected
  • Breakouts fail and price snaps back
  • Trading style: fade the extremes — sell the highs, buy the lows
NEGATIVE γ
spot below the flip

Dealers are net accelerants. Every move gets amplified by their own hedging.

  • Volatility expands
  • Ranges break, levels give way
  • Trends run further than they should
  • Trading style: stop fading — go with the move

The GAMMA REGIME strip tells you which one you're in

You don't have to work this out yourself. The terminal prints the answer as a single line, with three markers on it:

Marker What it is Why you care
ZERO Γ The flip point — where total gamma crosses zero. Above it you have brakes. Below it you don't. The single most important level on the screen.
SPOT Where price is now. Its position relative to ZERO Γ is the regime. Distance matters too — sitting 0.2% above the flip is not the same as 3% above.
VOL TRIGGER Our approximation of the single biggest cluster of stabilising gamma. Roughly the ceiling of the stabilised zone — where the pinning pressure is strongest.
The GAMMA REGIME strip showing POSITIVE gamma, with ZERO gamma at 4006.5, spot at 4070.4 and the vol trigger at 4119.3
Read it left to right: red zone below the flip, green zone above. Here spot 4070.4 sits +1.59% above ZERO Γ 4006.5 — comfortably in the stabilised regime, with the VOL TRIGGER at 4119.3 marking the top of the pinning zone. Where the SPOT marker falls decides how you trade the entire session.
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Distance is a dial, not a switch

The flip isn't a light switch that clicks at the exact price. Gamma fades gradually as you approach it. Sitting far above the flip means strong brakes; hovering just above it means weak brakes and a regime that could invert on a single bad candle. Watch the gap, not just the sign.

3Reading the GEX profile

Green bars, red bars, and one big line

The GEX PROFILE tab breaks the total down strike by strike. Each bar is the net gamma sitting at that price. The colour is the sign — and the sign is everything.

positive γ — support / pin negative γ — acceleration cumulative Σ — flip = zero-cross
The GEX PROFILE tab in SWING mode, showing green positive-gamma bars, red negative-gamma bars near the flip, the blue cumulative curve, and the call wall, spot, max pain and GEX flip marker lines
Bars run left (negative) and right (positive) from the centre line; the dashed markers are CALL WALL 4142, SPOT 4068.9, MAX PAIN 4011 and GEX FLIP 3994. Note the structure: a heavy green cluster at 4001–4033 sitting below price, thin bars between spot and 4033, and the red bars at 3979–3990 tucked just under the flip.

Green bars — the brake

A green bar marks a strike where dealers are long gamma. Price approaching it from either side meets opposing flow. It slows down.

MYTH
"A green bar pushes price away — it's a bounce level. I'll buy the touch and target a reversal."
REALITY
A green bar is a brake and a magnet, not a trampoline. Dealer selling into a rally doesn't shove price back down — it stalls it. Dealer buying into a dip doesn't launch it — it cushions it. Price gets stuck around the level, not rejected from it. Expect a pin and trade the chop; expect a bounce and you'll sit in a losing reversal while price grinds sideways on the level for hours.

Red bars — no brakes

A red bar marks a strike where dealers are short gamma. Here their hedging joins the move instead of opposing it.

MYTH
"A red bar is support from above — and if it breaks, the move accelerates downward. Coming from below it's resistance, but breaking it upward is fine."
REALITY
Negative gamma is completely symmetric. It has no directional bias at all. Price falling into red gets sold into and accelerates down. Price rallying into red gets bought into and accelerates up. There is no braking side. A red bar is not support, not resistance — it's a speed zone. Leaning on one as a level is the expensive version of this mistake.
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Why almost everyone gets this backwards

Red bars nearly always sit below spot, because customers are net buyers of puts and dealers end up short them. So in practice you only ever experience negative gamma as a downside accelerant, and it's natural to generalise from that. But when price does trade up through a negative-gamma pocket, it goes fast — that's a large part of what a melt-up or a short squeeze actually is, mechanically.

The four marker lines

Line What it means
GEX FLIPThe zero-cross of the blue cumulative curve. The regime boundary. Outranks every individual bar on the chart.
CALL WALLThe largest positive-gamma strike above spot. Acts as a hard ceiling and an upside magnet into expiry. A different animal from a normal green bar purely because of its size.
PUT WALLThe mirror below spot — the strike that tends to act as the floor.
MAX PAINNot a gamma level. It's an open-interest calculation — the strike where the most option value expires worthless. A weak drift target that strengthens as expiry approaches. Keep it mentally separate from everything else on this screen.
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The blue cumulative line

It's a running total of gamma across strikes. Only one thing on it really matters — where it crosses zero, because that's the flip. But its slope is a useful second read: a steep curve means gamma stacks up fast as price moves, so the regime is firmly held. A flat curve means the flip is fragile.

4Call γ vs Put γ

The net profile, taken apart

The GEX profile shows you the net at each strike — calls and puts already added together. The CALL / PUT Γ tab un-does that addition and shows you the two halves side by side.

This matters because a small net bar can hide two enormous opposing stacks. A strike showing near-zero net gamma might be genuinely empty — or it might be a battleground with huge call gamma and huge put gamma cancelling out. Those two situations behave completely differently when one side unwinds.

The CALL / PUT gamma tab, with call gamma fanning right in green and put gamma fanning left in red, and the GEX flip line marked at the lower strikes
Call γ to the right, put γ to the left. Call-γ stacking above spot + put-γ below is the classic pin structure. Look at 4087 and 4032 here — both carry a heavy stack on each side. Those are battleground strikes, and the net profile alone would never have shown you that.
5The time dimension

Gamma has a shelf life

A gamma level is not a permanent feature of the market. It belongs to an expiry — and when that expiry passes, the level simply stops existing. This is the part most people miss entirely.

0DTE
expires today

Gamma is enormous here — it concentrates violently as expiry approaches. These are the tightest, most powerful pins you'll see. And they evaporate completely at the close. Tomorrow they're gone.

SWING
the aggregate book

The blend across expiries. Weaker per-strike, but far more persistent — these levels survive days and weeks. This is your structural map.

How to combine them

Use SWING to draw the map — the walls and the flip that define the week. Then switch to 0DTE to time entries against the levels the market is actually fighting over today. When a 0DTE level lands on a SWING level, that price is doubly important.

The strike × expiry heatmap

The profile collapses every expiry into one column. The GEX heatmap un-collapses it: strikes run up the side, each column is a separate expiry, and colour shows call-heavy (green, support) vs put-heavy (red, acceleration) at that intersection.

The columns are expiries, not days

This trips up everyone on first look. The columns are the 8 nearest expiration dates — leftmost is nearest (often today's 0DTE), rightmost is furthest out (~2–3 weeks). They are not evenly spaced in time and they are not a count of days. The bar underneath each column is that expiry's recency weight — the swing aggregate leans hardest on the nearest dates.

The GEX heatmap laid out as strikes against the eight nearest expiry dates, with the orange spot line running across it and blue expiry-weight bars along the bottom
Reading it: scan along the orange spot line to see how the regime changes as you look further out in time. Here the near columns (07/22, 07/24) run green around spot while the later ones (07/31, 08/03) turn red — the brakes are a near-term feature, and they thin out as you go right. A level that's green near-term but red further out is a wall with an expiry date on it.
6Vanna & Charm

The two cousins of gamma

Gamma answers one question: how does the dealer's hedge change when price moves? But price isn't the only thing that changes. Two other forces move that hedge — and both get their own tab.

Greek Hedge changes when… What it drives
GAMMA Price moves Pinning and acceleration. The main event.
VANNA Implied volatility moves Flows triggered by a vol spike or a vol crush — even if price hasn't moved at all. Marks the strikes where a change in fear forces the most re-hedging.
CHARM Time passes The classic drift into expiry. Hedges unwind on their own as the clock runs down — this is why Fridays have a character of their own.
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Why vanna looks upside-down compared to gamma

Vanna flips sign around spot and concentrates in the wings and in longer-dated expiries — the opposite of gamma, which peaks at 0DTE and near the money. So a vanna map that looks inverted next to your gamma map isn't broken; it's measuring a different force. Gamma is the near-term price story. Vanna is the volatility story, and it lives further out.

Per-strike vanna exposure, positive above spot and negative below
VANNA — green above spot, red below. Big stacks mark where a vol change forces the most re-hedging.
Per-strike charm exposure, negative above spot and positive below
CHARM — and note it's the exact mirror. Big stacks mark where time decay alone will drag hedges into the close.

You don't need these to trade gamma. Treat them as the second layer: when gamma tells you the regime and vanna or charm agrees on the same strike, conviction goes up.

The same strike-by-expiry heatmap switched to VEX mode, showing vanna exposure concentrated in the wings and the longer-dated expiries
The same heatmap switched to VEX. Compare it against the GEX version above — the colour has moved outward and rightward, into the wings and the longer-dated expiries. That's the visual proof that vanna is a different force living on a different part of the board.
7How to use it

A four-step routine

Gamma doesn't give signals. It gives you the rules of the session — how the market is going to behave when it reaches a level. You still bring the trade.

The one-sentence version

Above the flip, sell the highs and buy the lows into green clusters and expect them to stall. Below the flip, stop doing that — respect the direction and let it run.

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Confluence with the rest of the terminal

A gamma wall landing on a forecast cone band (Field Guide No. 01) or on an options heatmap wall (No. 02) is a high-conviction level — independent models agreeing. And the expected move band tells you whether reaching that wall today is even realistic: if the wall sits outside the ±1σ range, it's a target for later in the week, not a level for this session.

8Honest caveats

What gamma can't tell you