Cumulate percentage returns.

so I believe what I previously posted is still correct.  I think what you posted in the image is a column of dates (end of the month) and the corresponding return rate for that month.  So if you started with $100 then on 20223-11-30 after the -3.84% return you would have about $96.16 (i.e. a loss of 3.84%).  Here is the spreadsheet (also attached) I have laid it all out as I believe you need:

so in column C is the changing value based on those rates.

on row 16 is the net return rate based on that cumulative value

on row 18 is the formula I gave to calculate the cumulative return rate based just on those rates

on row 20 is what the geomean function gives you, which is the 'average' rate that if you earned each month would have been equal at the end and this is shown in columns G & H

I hope this helps but let me know if I'm still not understanding you