Five numbers that explain every option.
Greeks sound intimidating. They're not. Each one answers a simple question about how your option behaves. Start with Delta, learn the rest at your own pace.
Delta
Delta tells you how much your option price moves for every $1 move in the stock. ATM calls have delta ≈ 0.50. Also approximates the probability of expiring in-the-money.
Gamma
Gamma measures how quickly Delta itself changes — the acceleration of your option. Highest for ATM options near expiry. Responsible for gamma squeezes.
Theta
Theta is the daily cost of holding an option. Every day that passes, your option loses value — faster as expiry approaches. Option sellers profit from Theta.
Vega
Vega measures how much your option price changes when implied volatility moves by 1%. Critical to understand before earnings — IV crush is caused by Vega.
Rho
Rho measures how much your option price changes when interest rates move by 1%. Mostly matters for LEAPS — safe to ignore for weekly and monthly options.
Start with Delta. Everything else builds on it.
If you understand delta, gamma starts to make sense (it's just how fast delta changes). Once you know gamma, theta and vega fill in the rest of the picture. Rho is the quiet one — only matters if you hold long-dated options.