Explain the Concept of ‘Delta Decay’ for ITM Options

'Delta decay' for In-the-Money (ITM) options refers to the phenomenon where an option's Delta moves towards 1 (or -1) as time to expiration approaches. This is not strictly a 'decay' in the negative sense, but rather a convergence to the theoretical maximum.

As the uncertainty of the option expiring ITM decreases with less time remaining, the option's price movement more closely mirrors the underlying asset. This convergence is driven by the decreasing time value and the increasing certainty of the option's intrinsic value.