When is BANKNIFTY INDEX FUTURES expiring?

The nearest expiration date for BANKNIFTY INDEX FUTURES is Nov 30, 1899.

When should I sell BANKNIFTY INDEX FUTURES?

The best time to sell a futures contract is when you've already made money on the investment, but still have plenty of time left before the expiration date. Thus, a good option would be to sell BANKNIFTY INDEX FUTURES before Nov 30, 1899.

What is Open interest? How can I use it to trade BANKNIFTY INDEX FUTURES?

Open interest is the number of contracts held by traders in active positions — they're not closed or expired. For BANKNIFTY INDEX FUTURES this number is 0. You can use it to track a prevailing market trend and adjust your own strategy: declining open interest for BANKNIFTY INDEX FUTURES shows that traders are closing their positions, which means a weakening trend.