What Is the Relationship between Theta and Gamma near Expiration?

Near expiration, the absolute values of both Theta and Gamma increase significantly, exhibiting an inverse relationship in effect. High Gamma means the option's Delta changes rapidly with small moves in the underlying, leading to large swings in option price.

Simultaneously, high Theta causes rapid value decay if the underlying price remains stagnant. This combination creates high risk and reward for short-term options.