How can oi change after market close?

After market close at 3.30 pm .
I check compare the o.i. of any particular future scrips :
There is drastically change in the o.i. at 3.30 pm ; 4 pm ; 7 pm !!!

How this is possible?

How can the o.i. alter after the market is closed?

Awaiting for the reply…

Can check this.