On mid term frame Bank-nifty is clearly in uptrend and has been trading in clear parallel channel since past one odd year. Short term action too in an uptrend but has formed a rising wedge with negative divergence in overbought region which is a sign to get cautious and take partial profits on every rise.
Also BN has now reached almost to the upper end of a wedge and may see some resisted action in coming days. For extension in current rising action, BN must move above 12800/900 range. Any action above this will only allow BN to test channel's upper end currently placed near 13600/700 zone.
On the other side, move below 11900-12180 can turn the short term trend down and force BN to test back crucial supports on the downside to keep mid term trend up. On indicators, until RSI stays above 50/55 region, trend may not change, but below 50-55, it is likely to turn bearish and some sizable profit taking may be seen.