quarterly and yearly returns in vba

I have monthly returns of 10 portfolios from 1927 till 2018. I already multiplied the percentages by 0,01 and calculated each month quarterly and yearly returns. The problem is however that in two consecutive months this gives results with overlapping observations (for instance March*April*May). Hence, I need to create a function in VBA to calculate those returns without overlapping observations. So that for instance quarterly returns are only on a quarterly basis (Jan-Mar)

Hope anyone can help me out and thanks in advance!

Thank you for your reply.

Please see attached a sample workbook. In the "before" sheet is the data. First the percentages and next to that the percentages multiplied by 0,01
In the "after" sheet are two examples of what I need. The compounded returns of those data but only per actual quarter and year, so jan, feb, mar and so on instead of feb, mar, apr.
I alsno need a VBA code for yearly returns.

I hope this clears it up a bit

2016. Problem is that it needs to be a VBA function but I'm not that good in it at the moment. I know how to make a compund formula in VBA but not how to make sure that there are no overlapping observations. That is what I need in order to be able to perform a financial time series regression.

Ah it is helpful, thank you! Reason a VBA code was requested is to make it more easily tranferable between various datasets but im not sure how to get it aggregated by using VBA....