GAMMA — DELTA'S ENGINE
- Gamma is how fast delta itself changes — delta's engine.
- It's biggest at-the-money and explodes near expiration.
- Long options are long gamma: you gain from movement, and pay for it with theta.
How fast your speedometer itself moves. Why 0DTE whips. If delta is the speedometer, gamma is the accelerator's sensitivity. Far from expiration it responds gently. Near expiration — especially at-the-money — a light tap sends the needle swinging.
THE TAKEAWAYS
- Gamma 0.0099: every $1 SPY move shifts your delta by ~0.01.
- Gamma is biggest at-the-money and explodes near expiration.
- Long options = long gamma (good when price moves). You pay for it with theta.
WORKED EXAMPLE — STEP BY STEP
- Your call sits at 0.55 delta with gamma of 0.0099.
- SPY rises $1 → delta ≈ 0.56. Another $1 → ≈ 0.57. Your exposure accelerates as price moves with you.
- Near expiration, that same acceleration is why a position can feel calm at 10am and violent by noon.
The losing variant is the whipsaw: SPY drops $1, delta falls just as fast, and the position's exposure shrinks after the damage — then a bounce finds you underweight. Near expiry, size for the flip, not the hope.
WHAT TIME & IV DO TO IT
Gamma grows as expiration approaches and peaks at-the-money. The same position that felt calm at 45 DTE can whip at 2 DTE — time literally makes your delta less stable.
COMMON BEGINNER MISTAKES
- Sizing a 0DTE trade like a 45-DTE trade.
- Being surprised when delta flips near expiry.
- Chasing gamma while ignoring the theta bill that comes with it.
CHECK YOURSELF
Q1. Gamma measures…
Q2. Your gamma is 0.0099. SPY moves $1. Delta shifts by about…
Q3. Gamma is biggest…
DO IT ON PAPER
In the Robinhood chain, compare the gamma of the nearest expiry with one 45+ days out, near the same strike. See which position would feel twitchier — and why your size has to change between them.