Autofilling of formula for every 5th row

Hello,

Can somebody please help in running a auto filling of highlighted formula for rebalancing after every fifth row for eight years daily data which I cannot do manually. Which way would be easiest macro coding or is there any simplest way?
I am new to coding for macros in excel.
Please find my sample spread sheet attached.

Appreciate the help in advance.

Thanks,
Jasme