What Is Gamma in Options Trading?
Gamma is an options Greek that measures the rate of change of delta for every Rs 1 move in the underlying asset. While delta tells you how much an option price moves, gamma tells you how quickly delta itself changes. Options with high gamma are more sensitive to price movements and carry higher risk and reward potential.
Why Gamma Matters
Gamma is highest for at-the-money options and increases sharply as expiry approaches. This makes ATM weekly options on Nifty and Banknifty extremely volatile near expiry. A small move in the underlying can cause a large change in delta, which then magnifies the change in option premium.
- Long option positions (buyers): Have positive gamma; they benefit from large moves in either direction.
- Short option positions (sellers): Have negative gamma; large sudden moves hurt them significantly.
- Deep ITM or OTM options: Have very low gamma; delta does not change much.
Gamma Risk Near Expiry
In Indian markets with weekly Nifty and Banknifty expiries, gamma risk is a critical consideration on expiry day. Options that were OTM can quickly become ITM with a moderate market move, causing their delta to jump dramatically. This is why selling options near expiry can feel like collecting small premiums but carry the risk of sudden large losses.
Gamma Scalping
Professional traders use gamma scalping, a technique where they buy high-gamma options and continuously delta-hedge by trading the underlying. When the market moves, they rebalance their delta, effectively capturing profits from large swings. This strategy works best in volatile markets with frequent sharp moves.
Gamma and Portfolio Management
When managing a large options book, portfolio gamma indicates overall sensitivity to market moves. A gamma-neutral portfolio means the portfolio's delta will not change significantly with small price movements. Most institutional options desks in India actively manage gamma exposure along with delta and vega.
Key Takeaway
Gamma is the accelerator of delta, making it essential to understand for anyone trading options in Indian markets. High gamma near expiry is what drives explosive moves in weekly options. Whether you are buying options for leverage or selling them for premium income, understanding gamma helps you manage risk and set realistic expectations. Use the Lemonn app to track Greek values and stay informed about expiry-day volatility in Indian F&O markets.
