Gamma measures the rate of change of delta—how much delta changes for every $1 move in the underlying stock. It’s the second derivative of option price with respect to stock price. Gamma is highest for at-the-money (ATM) options near expiration. High gamma means delta (and therefore option price) can change rapidly with small stock moves.
- Measures how fast delta changes
- Highest for ATM options near expiration
- Positive for long options, negative for short options
How Gamma Works
Gamma shows how delta accelerates:
Gamma Effect:
Current: Stock $100, Call Delta 0.50, Gamma 0.05
Stock rises $1 to $101:
New Delta = 0.50 + 0.05 = 0.55
Stock rises another $1 to $102:
New Delta = 0.55 + 0.05 = 0.60
Gamma makes your delta grow in your favor
when stock moves your way.
Stock falls $2 to $98:
New Delta = 0.50 - (2 × 0.05) = 0.40
Gamma reduces your delta when stock
moves against you.
Quick Reference: Gamma Values
| Option Status | Typical Gamma | Reason |
|---|---|---|
| Deep ITM | Low (0.01-0.02) | Delta near 1, doesn’t change |
| ATM | Highest (0.05-0.10) | Most uncertainty |
| Deep OTM | Low (0.01-0.02) | Delta near 0, doesn’t change |
| Near Expiry ATM | Very High | Gamma risk! |
Example: Gamma in Action
ATM Option Near Expiration:
| Stock | Delta | Gamma | Option Change |
|---|---|---|---|
| $100 | 0.50 | 0.15 | - |
| $101 | 0.65 | 0.12 | +$0.58 |
| $102 | 0.77 | 0.08 | +$0.71 |
| $103 | 0.85 | 0.05 | +$0.81 |
Delta accelerates as stock moves ITM.
Gamma measures how fast delta changes with stock price movement. High gamma means your option’s sensitivity accelerates quickly. ATM options near expiration have extreme gamma—small stock moves cause large delta swings. This is gamma risk.
Gamma Risk
For Option Buyers
High gamma is good. When stock moves your way, delta increases, making you more money. When it moves against you, delta decreases, limiting losses.
For Option Sellers
High gamma is dangerous. You’re short gamma, meaning delta moves against you. Near-expiration ATM short options can produce huge losses from small moves.
Gamma by Time to Expiration
| Time Left | ATM Gamma | Risk Level |
|---|---|---|
| 60+ days | Low | Manageable |
| 30-60 days | Moderate | Normal |
| 7-30 days | High | Elevated |
| 0-7 days | Very High | Extreme |
Gamma Strategies
Long Gamma (Buyers)
Own options, benefit from big moves in either direction. Gamma scalping profits from volatility.
Short Gamma (Sellers)
Collect premium, hope stock stays still. Risk large losses from big moves.
Gamma Neutral
Use spreads to offset gamma. Reduces risk but caps profit.
Common Mistakes
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Ignoring gamma near expiration – Short ATM options become extremely risky.
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Not understanding gamma scalping – Delta hedging requires understanding gamma.
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Confusing gamma and delta – Delta is position, gamma is how position changes.
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Forgetting gamma is positive/negative – Long options positive gamma, short negative.
How JournalPlus Tracks Gamma
JournalPlus logs gamma exposure for options positions, helping you understand your risk from delta changes and manage positions approaching expiration.
