Gamma is an options Greek that measures how fast an option's delta changes when the underlying price moves by one unit. It shows how sensitive delta itself is to movement in the underlying market.
Gamma is highest when an option is near its strike price and close to expiry. At that point delta can shift quickly, so the option's price sensitivity rises or falls sharply as the underlying moves.
Delta measures how much an option's price moves when the underlying moves; gamma measures how much that delta moves. High gamma makes profit and loss swing faster as the underlying changes, while low gamma means delta drifts slowly. Traders watch gamma to manage options risk, hedging needs, and position exposure.
A call option has a delta of 0.50 and a gamma of 0.10.
If the underlying stock rises by USD 1, the delta increases from 0.50 to 0.60.
If the stock falls by USD 1, the delta decreases from 0.50 to 0.40, assuming other factors stay the same.