StrikeGEX Playbook

SPX 0DTE Dealer Positioning: the mechanics that shape the session

Ten minutes, plain language, no signals. What dealer hedging is, why it moves the tape, and how to read a positioning map in 30 seconds.

READING TIME ~10 MIN · EDUCATIONAL ONLY · NOT FINANCIAL ADVICE

1. Why dealers move the tape

Most SPX options don't trade between two traders with opinions. One side is usually a market maker — a dealer — whose job is to quote, fill, and then carry the position without directional risk. Dealers don't want your bet. They want the spread. So every contract they carry gets hedged with the underlying.

Hedging isn't a one-time event. An option's directional exposure — its delta — changes as price moves, and the rate of that change is gamma. A dealer who is hedged at 6,400 is no longer hedged at 6,410, so they buy or sell futures to get flat again. Multiply that adjustment across the whole SPX board and you get a persistent, mechanical flow that has nothing to do with news, earnings, or anyone's opinion.

That flow is the point. It's large, it's rule-driven, and it concentrates at specific strikes. Positioning data doesn't predict where price wants to go — it maps where the hedging machine will push back, and where it will pour fuel.

2. The two regimes

Everything downstream follows from one number: net GEX — the net gamma dealers carry across the board. Its sign sets the session's mechanical character.

Neither regime says "up" or "down." The regime says how the tape is likely to behave — absorb or accelerate. Knowing which machine is running before the open is the single highest-leverage piece of context on the board.

3. The King Node

Gamma isn't spread evenly across strikes. It clusters — and the strike carrying the largest concentration is the King Node. It's the level where dealer hedging activity is heaviest, which makes it the most structurally significant price on the board.

In a positive-gamma tape, price that drifts away from the King Node meets hedging flow that leans back toward it — the "pin" behavior 0DTE traders know well, strongest into the afternoon as expiry approaches. In a negative-gamma tape the King Node still marks the board's center of gravity, but the leash is off: it acts less like a magnet and more like the reference level the session is trading around.

The King Node is not a price target. It's the answer to "where is the heaviest hedging on the board right now?" — and "right now" matters, because it can migrate intraday as positioning changes.

4. Walls

Above and below spot, two more concentrations frame the session:

• Call Wall — the strike with the largest call gamma above price. Approaching it, dealer hedging pressure increasingly leans against further upside. Rallies often slow, stall, or grind there.
• Put Wall — the same structure below price on the put side. Selloffs frequently decelerate into it.

Between the walls is the range dealer positioning currently frames. Price living inside it is the machine working as designed. Price escaping it is information — the board that framed that range no longer describes the tape, and positioning is being rebuilt.

Classic support and resistance is drawn from where price has been. Walls are drawn from where hedging obligations are now. That's the whole difference, and it's why walls move intraday while yesterday's chart lines don't.

5. The 0DTE session arc

Same-day options are now the majority of SPX volume, and they change the physics of the map:

• Positioning builds fresh every morning. A large share of the day's gamma doesn't exist until the session's flow creates it.
• Gamma sharpens into the close. As expiry approaches, hedging sensitivity around at-the-money strikes intensifies — afternoon pins and afternoon accelerations both come from this.
• At the close, it vanishes. Expiring strikes take their gamma off the board. Tomorrow is a new map.

Practical consequence: a positioning read has a shelf life. A map from 9:40 AM describes 9:40 AM. Any tool showing dealer levels should tell you exactly when its data was fetched — and you should distrust any level without a timestamp attached. (This is why every StrikeGEX reading carries an as-of stamp, and why the core map refreshes every 60 seconds in market hours.)

6. The 30-second read

Order matters. Run it the same way every time:

• Regime first. Positive or negative net gamma — absorb or accelerate. This frames everything else you're about to see.
• King Node second. The heaviest strike. Where is it relative to spot?
• Walls third. The framed range. How much room is there in each direction?
• Spot last. Inside the range or outside it? Near the King or stretched from it?

That's the read: regime, King, walls, spot. It doesn't tell you what to trade — it tells you what kind of tape you're standing in, which is the context every plan needs before the first entry.

7. Verify before you trust

Positioning data earns trust one session at a time. The StrikeGEX morning SPX levels are published free every trading day, and the close recaps grade them against what the tape actually did — misses included. Watch the map next to the tape for a week before you pay anyone for it, including us:

• Morning levels: strikegex.com/spx-gex-levels
• Graded recaps: strikegex.com/king-track

Glossary

GEX

Gamma exposure — the aggregate gamma dealers carry, by strike or netted across the board. The map of forced hedging.

Net GEX

The board-wide net. Its sign sets the regime: positive absorbs, negative accelerates.

King Node

The strike carrying the largest gamma concentration — the heaviest hedging level on the board.

Call Wall / Put Wall

The largest call-side concentration above price and put-side below — the levels that frame the dealer range.

0DTE

Zero days to expiration — options expiring today. The majority of SPX flow, and the reason the map moves intraday.