Does Gamma Increase or Decrease as an Option Approaches Expiration?

Gamma generally increases for at-the-money options as expiration approaches. This is because the option's Delta becomes highly sensitive to the underlying price near expiry, causing rapid shifts from 0 to 1 or vice-versa.

For options that are deep in-the-money or far out-of-the-money, Gamma decreases toward zero near expiration.