Open Interest is the number of FIN NIFTY option contracts that are still open — written but not yet closed out or settled. This page plots call and put OI at every strike on the NSE FIN NIFTY chain, alongside the change in OI. Rising OI at a strike means fresh positions are being built there; falling OI means positions are being unwound. The strikes carrying the heaviest call OI are commonly watched as resistance and the heaviest put OI as support.
FIN NIFTY covers the wider financial-services basket — banks, NBFCs, insurers and housing finance — so it reacts to rate, credit and policy news. OI tells you where positions sit, not which way price will go, so read it with the FIN NIFTY Put Call Ratio for net sentiment, the max pain strike for the expiry-day magnet, and the option chain for the strike-by-strike detail. All three are linked above.