Bank Nifty trading in the trend line channel. *On the upper side major supply zone @ 21500-21800 and downside short turm major demand zone @ 19000-19200. Also, there is trendline support near the demand zone. In any case, if Bank Nifty will break and sustain below 19000 then minimum 1000 points downside range will open. *The yellow zone is an OTM option selling zone for me. I will avoid taking a trade-in FUT in this yellow zone.