I don't like to Speculate but since you have asked for it.
Looking at the OI, the Range MAX TOP for this series could be 6430 since the MAX OI is at 6200-6400 and MAX Pain is also at 6300 (Average of 6200 and6400).
So If MAX OI does not change to say 6450/6500 then we can consider 6400 as the TOP and take positions accordingly.
Expiry is a little far away and so we have a long time for that.
If I Remember correctly Yesterday or Day before Yesterday NIFTY Futures made a Freak low of 5600. So even 5600 should be possible
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On a Serious note, Just to purely speculate 6500 could also be top looking at today's COI of 6300-6500.
Plus I normally calculate 60 points at a time for NIFTY. Accordingly this Series has been going on NON STOP from 5980.
So 240 points from 5980 would be 6220, where there was a small correction.
And 240 points from 6220 would be 6460.
So may be 6460 might be top of this Series.
But I have always seen that the Last 50 points is very difficult to Get and so the First Correction might actually start at 6460-50=6410.
So Watch 6410 carefully... 6400/10 is already the RESISTANCE in the daily charts and the hourly charts. As per OI also 6400 is the RESISTANCE right now.
Those who have been lucky with the Bull ride from 5980 / 6220 then one must seriously thinking of booking at least 50% profits at 6400