Last week both indices closed lower on a weaker note. The Nifty closed 200 and Bank Nifty 1200 points down on a close-to-close basis.
Next week, the 17370-400 zone will play an important role in deciding the Nifty Index trend. And on the downside, a sustainable move below the 17100 will strengthen the bears more.
For Bank Nifty, the 39400-300 zone will be crucial. A sustainable move below that zone can push Bank Index further lower. And the 39900-40000 zone will act as the resistance on the higher side.

Nifty Weekly Gann levels
Next week, 26 & 29 September, are the Gann dates for the Nifty 50 Index.
Resistance: 17400. Above that, the Nifty can trade higher and reach 17480/17580/17700/17840 levels.
Support: 17190. Below that, the Nifty can move lower towards 17110/17010/16890/16750 levels.

Bank Nifty Weekly Gann levels
Next week, 26 & 29 September, are the Bank Nifty Gann dates.
Resistance: 40000. Above that, the Bank Nifty Weekly trend can change, and it can start moving towards 40200/40500/40900/41400 levels.
Support: 39300. Below that level, Bank Nifty can move lower towards 39100/38800/38400/37900.
Note: The above levels are only for study. Not Buy/Sell advice.