What Are the Options Greeks?
Options Greeks are sensitivity measures that describe how an option's price changes in response to different market variables. For most retail traders, the Greeks are just risk metrics on a brokerage screen. But for market makers and dealers, they are hedging obligations — and that hedging activity is what moves the underlying stock or index.
Understanding the Greeks is the foundation for reading gammaflowpulse's dealer-positioning maps.
Delta (Δ) — Directional Exposure
Delta measures how much an option's price moves for every $1 move in the underlying.
- A call with delta 0.50 gains ~$0.50 for every $1 the stock rises
- A put with delta -0.40 loses $0.40 for every $1 the stock rises
- Delta ranges from 0 to 1 for calls, -1 to 0 for puts
Why it matters for trading:
Delta tells you your directional exposure. An at-the-money option has delta near ±0.50. Deep in-the-money options behave almost like the stock (delta near ±1). Far out-of-the-money options have tiny deltas — you need a big move to profit.
Dealer implication:
When dealers sell calls, they own negative delta. To stay delta-neutral, they buy the underlying stock. This buying and selling pressure is tracked in the DEX (Delta Exposure) map.
Gamma (Γ) — The Rate of Change of Delta
Gamma measures how fast delta changes as the underlying moves.
- High gamma = delta changes quickly with each tick
- Low gamma = delta is relatively stable
Options near expiration and near the strike price have the highest gamma. This is why 0DTE (zero days to expiration) options are so explosive — a small move creates a large delta change, forcing dealers to aggressively hedge.
Why it matters for trading:
If you're long gamma (you own options), big moves work in your favor — your delta increases as the market moves your way. If you're short gamma (you sold options), every move works against you.
Dealer implication:
This is the core of GEX (Gamma Exposure). When dealers are net short gamma (negative GEX), they must buy when the market rises and sell when it falls — amplifying moves. When dealers are net long gamma (positive GEX), they do the opposite — dampening volatility. The gamma flip level on the GEX map is the price where this dynamic flips.
Vega (ν) — Sensitivity to Implied Volatility
Vega measures how much an option's price changes for every 1-point change in implied volatility (IV).
- Long options (calls or puts) have positive vega — they gain value when IV rises
- Short options have negative vega — they lose value when IV rises
Why it matters for trading:
Buying options ahead of an event (earnings, Fed meeting) means you're buying vega. If IV doesn't spike as expected, or collapses after the event, your options can lose value even if the stock moves in your direction. This is called a volatility crush.
Dealer implication:
Dealers manage vega by adjusting their option portfolios when IV shifts. This flows into the VEX (Vanna Exposure) map, which captures how dealer delta hedging responds to changes in implied volatility.
Theta (Θ) — Time Decay
Theta measures how much an option loses in value each day as it gets closer to expiration, all else equal.
- Theta is always negative for option buyers (you lose value daily)
- Theta is positive for option sellers (time works in your favor)
Why it matters for trading:
Time decay accelerates as expiration approaches. An ATM option decays slowly early in its life, then rapidly in the final week. Selling options (positive theta) profits from this — but you take on gamma risk in return.
Dealer implication:
Theta decay redistributes value between option buyers and sellers. It also interacts with Charm — as theta erodes value on OTM options, the effective delta of those options drifts toward zero, forcing dealer delta re-hedging.
Vanna — Where Volatility Meets Direction
Vanna is a second-order Greek that measures how delta changes when implied volatility changes (or equivalently, how vega changes when the underlying moves).
- When IV drops, call deltas fall and put deltas rise — dealers must re-hedge
- This re-hedging creates real buying or selling pressure in the underlying
Why it matters for trading:
Vanna flows are strongest when IV is changing rapidly — typically after a sharp move or around major events. A vol crush can trigger significant vanna-driven buying (dealers covering short delta from fallen call deltas) even without any further move in the underlying.
Dealer implication:
The VEX (Vanna Exposure) map on gammaflowpulse tracks where vanna-driven hedging pressure is concentrated. High vanna at a strike means that level is sensitive to IV changes — a vol spike or crush can cause outsized moves.
Charm (Δ decay) — The Time-Delta Effect
Charm (also called delta decay) measures how much delta changes over time as an option approaches expiration.
- OTM options lose delta as expiration approaches (charm pulls delta toward zero)
- ITM options gain delta as expiration approaches (charm pulls delta toward ±1)
Why it matters for trading:
Charm effects are most visible on Fridays and in the final days before expiration. As time passes, dealers holding short OTM options see their delta exposure shrink — they must unwind hedges, which can cause mechanical moves in the underlying.
Dealer implication:
The CHEX (Charm Exposure) map shows where charm-driven delta re-hedging is most likely to occur through the trading day. CHEX flows are especially relevant for understanding afternoon drift and end-of-day pin behavior near large open interest strikes.
Putting It All Together
- Delta → directional exposure → DEX map
- Gamma → rate of delta change → GEX map
- Vega → IV sensitivity → VEX (indirect)
- Vanna → delta shift from IV change → VEX map
- Charm → delta shift from time → CHEX map
The key insight: options dealers are not passive. Every Greek creates a hedging obligation. When you understand which Greek is dominant on a given day — and where the largest concentrations of exposure sit — you can anticipate the mechanical flows that push price around, independent of fundamental news.
Start with GEX to understand the volatility regime. Layer in VEX when implied vol is moving. Watch CHEX on expiration Fridays. Use DEX to understand the directional tilt from all open interest combined.