The 5-minute options primer
TL;DR
- A dealer takes the other side of your option and hedges by buying/selling the underlying to stay neutral.
- Gamma = how fast that hedge has to change as price moves. Near a strike and near expiry, it changes fast.
- This hedging is the pressure every GEXmon panel summarizes. You never compute it — the dashboard does.
You can read GEXmon without ever pricing an option. But five minutes of “why” makes every panel click. Here it is, no Greeks tables, no pricing models.
Calls, puts, strikes, expiry — in one breath
A call is the right to buy at a fixed price (the strike) by a date (the expiration). A put is the right to sell. That’s the whole vocabulary you need for this guide.
Dealers take the other side — and must stay neutral
When you buy an option, a market maker (a “dealer”) sells it to you. They’re not trying to bet against you; they earn the spread and want no directional exposure. So they buy or sell the underlying to offset the option’s directional risk. This is delta hedging — think of it as constant rebalancing to stay flat.
Gamma = how fast they have to re-hedge
As price moves, the amount a dealer needs to hedge changes. Gamma measures how fast. High gamma means a small move in price forces a big change in their hedge — so they trade the underlying more aggressively. That aggressive rebalancing is the pressure you feel as “invisible” support, resistance, pinning, or acceleration.
Add up dealer gamma across the whole market and you get one number with a sign. When dealers are net positive gamma, their hedging leans against the move — they sell rallies and buy dips, which calms the tape. When they’re net negative gamma, their hedging goes with the move — they buy rallies and sell dips, which amplifies it. That single sign is the Regime (Part 2). Everything else refines it.
Why 0DTE dominates intraday
Gamma is most violent near a strike and near expiry. Same-day options (“0DTE”) are always near expiry, so their gamma is huge and local — small price moves force outsized hedging. That’s why zero-dated options drive so much of the intraday tape, and why GEXmon’s default view is 0DTE (Part 6).
Deliberately left out
Greeks beyond gamma (vanna, charm), implied-vol surfaces, pricing models. They’re real, but you don’t need them to use this tool, and chasing them is how beginners drown. GEXmon summarizes all of it into the panels ahead. If you do want to learn them properly, our complete options trading guide walks through the Greeks, implied volatility and IV crush, and the core strategies from zero.
That’s the machinery. From here on it’s all dashboard: what each panel shows, what it means, and what to actually do with it.