Premium decay heatmap

Why premium decay matters

Option premium erodes over time even if the underlying doesn't move — the effect known as theta decay. Tracking how much each strike's premium has actually decayed since the session opened shows where option sellers are harvesting fastest today, and where buyers are instead seeing their positions grow (usually because the index moved in their favor).

How to read this heatmap

Each cell is the percent change in that strike's own last-traded price since today's open. Green means the premium has decayed (favors a seller who wrote it this morning); red means the premium has grown (favors a buyer, or a seller getting squeezed).

• Read per-strike, not against the index move — a strike can decay while the index itself is flat or even moving against it, depending on how far out-of-the-money it sits and how much time value it started with.
• ATM strike highlighted — the at-the-money strike carries the most time value and typically shows the clearest decay signal.

Methodology & data

Percent change is calculated against each strike's own last-traded price at today's open — the session's first captured snapshot, not a fixed reference point. Data streams live from AngelOne/NSE during market hours.