You can now trade the weekly Bank Nifty options - they expire on the Thursday of every week. So there was a Bank Nifty set of options that expired on 2nd June. There will be one set that expires tomorrow - 9th June. And then more on 16th June, 23rd June and then the last one on 30th June.
These options are shorter term and therefore introduce another way to lose money. Okay, another way to trade. But people who buy these options will, in general, lose money. Because something that decays within a week . . .