The change in OI was positive…
This means while Bank Nifty has gone up today, large number of traders expect a down move in Bank Nifty, hence they bought 15,500 Put Options.
Of course whether the traders are right or wrong in their expectation is a million dollar question
Highest OI got added at 15500PE with the (Decrease in Premium price) and (Increase in the Underlying Future price). So, I believe 15500PE options are being written(sold) and 15500 strike is becoming base for the BankNifty with next move to 16000.
Similar base is happening at 7800 strike of NIFTY!
((NIFTY -> 8000) & (BANKNIFTY -> 16000) & (S&P 500 ->2000)) == (ZerodhaCROWD(ZC) INDEX -> 8000)
Anybody want to bet ( ZC @ 8000 for tomorrow) OR (ZC @ 8000 for Next week Expiry)