Studying Bank Nifty charts on multiple time frames, We can see bank nifty make or break outside the trading range formed today. There is strong resistance which has been rejected 5 times and has never given a close above it. Expiry play should be interesting with Nifty Bank trying to again to cross the resistance (31720) and if rejected should see the very rapid down move as it is already at overbought levels. Should wait for friday's close to confirm Bank Nifty has made its top.