Max Pain

The theory behind max pain is that large option writers have some influence pulling spot toward that strike into expiry, though the evidence for it as a reliable predictor is mixed at best and it should be treated as one context data point, not a target level to trade against blindly.

Max pain is typically recalculated throughout the session as OI shifts, rather than fixed once at the start of the week — a strike that looked like max pain on Monday can easily be a different strike entirely by Thursday once enough OI has moved.

Example: if NIFTY's total OI is heaviest around 25,000, max pain theory suggests some pull toward 25,000 into expiry — but plenty of real expiries close well away from their calculated max pain strike, which is exactly why it belongs alongside other reads, not in place of them.