Understanding the Options Greeks: Delta, Gamma, Theta, Vega

The "Greeks" are mathematical measures that describe how an option's price changes in response to various factors. Understanding them is essential for position sizing, risk management, and strategy construction.

Delta: Directional Exposure

Delta measures how much the option price changes for a $1 move in the underlying. A call with 0.30 delta gains $0.30 when the stock rises $1. Delta also approximates the probability of expiring in-the-money. At QuantaEdge, we target 16-delta short strikes for iron condors — about 84% probability of profit per side.

Gamma: Rate of Change of Delta

Gamma measures how fast delta changes. High gamma means the position's directional exposure shifts rapidly. Gamma is highest for at-the-money options near expiration — which is why we exit iron condors with 7+ days remaining. Near-expiration gamma risk can turn a winning position into a loser in minutes.

Theta: Time Decay

Theta measures how much value the option loses each day. For option sellers, theta is profit: every day that passes with the underlying inside your strikes, you collect a small amount of premium. Our iron condor strategies harvest theta decay between 21-45 DTE, where the decay rate is steady without excessive gamma risk.

Vega: Volatility Sensitivity

Vega measures sensitivity to implied volatility changes. When IV rises, all options become more expensive. For premium sellers, rising IV after entry increases the cost to close the position. This is why we use IV rank filters — entering when IV is elevated gives us a structural tailwind as volatility mean-reverts.