Options Greeks Simplified: Delta, Gamma, Theta, Vega Explained

Why Options Greeks Matter

Options Greeks tell you how your option's price will change as market conditions change. Think of them as your option's vital signs — they help you understand your risk before the trade, not after.

Delta: Direction

**What it measures**: How much your option moves per $1 move in the stock.

• Call delta: 0 to 1.0 (0.50 delta = option gains $0.50 per $1 stock increase)
• Put delta: -1.0 to 0 (-0.50 delta = option gains $0.50 per $1 stock decrease)

**Quick rules**: - ATM options have ~0.50 delta - Deep ITM options approach 1.0 delta (moves like stock) - Far OTM options have near-zero delta (barely moves) - Delta also approximates the probability of expiring in the money

Gamma: Acceleration

**What it measures**: How fast delta changes as the stock moves.

High gamma means delta changes quickly — your option becomes more sensitive to the stock as the stock moves in your favor. Gamma is highest for ATM options near expiration. This is why near-expiration ATM options can produce explosive gains (or losses).

Theta: Time Decay

**What it measures**: How much value your option loses each day just from the passage of time.

• Long options: negative theta (time works against you)
• Short options: positive theta (time works for you)
• Theta accelerates as expiration approaches — an option loses more value per day in its final week than its first month

**Key insight**: If you're buying options, you're fighting theta. Make sure you have enough time for your thesis to play out. If you're selling options, theta is your friend.

Vega: Volatility Sensitivity

**What it measures**: How much your option's price changes per 1% change in implied volatility.

• 0.05 vega = option gains $0.05 per 1% increase in IV
• Long options benefit from rising IV
• Short options benefit from falling IV

**Key insight**: Before earnings, IV rises (expensive options). After earnings, IV falls (IV crush). If you're buying options before earnings, you need the stock to move MORE than the expected move to overcome the IV crush.

Putting It All Together