Why Greeks Matter
An option's price does not depend only on whether Nifty or Bank Nifty goes up or down. It also depends on time left to expiry and on expected volatility. The Greeks are measures that describe how sensitive an option's price is to each of these factors.
Delta: Sensitivity to Price
Delta estimates how much an option's price may change for a one-point move in the underlying. A call option with a delta of 0.5 may gain roughly half a point for every one-point rise in the index. Delta also loosely indicates the market's implied probability of the option finishing in the money.
Theta: The Cost of Time
Theta shows how much value an option may lose each day because expiry is getting closer. Time decay speeds up in the last few days before expiry, which is why buying out-of-the-money options close to expiry is difficult: the index must move enough and quickly enough to beat decay.
Vega: Sensitivity to Volatility
Vega measures how the option price changes when implied volatility changes. Option prices often rise before major events and fall after the event passes, even if the index stays flat. This is commonly called volatility crush.
Gamma: How Fast Delta Changes
Gamma shows how quickly delta itself changes as the underlying moves. It is highest for at-the-money options near expiry, which is why such options can move sharply in either direction.
Putting It Together
Before entering any option position, check the delta, how much theta you are paying every day, and whether implied volatility is already elevated. Options can lose their entire value, and this article is for education only, not a trade recommendation.
