Need help portfolio simulation

Sory but i don't know why your macro ruin my formula for example in C7 C8 C9, and why you use cell G37

If i - cell.Row >= 20 Then
    Range("G37") = 20
Else
    Range("G37") = i - cell.Row
End If

Macro can not use cell G37, Cell G37 is only change average. If Cell G37=20 then average for each stock is for 20 last day so that cell can not be changed. Maybe this way:

1) Macro copy cell B39: to the end,
2) next paste to G37
3) Macro run solver
4) result from J31 copy to the cell B39
5) loop (cell B40, B41 etc) loop stop when meet empty cell.

Sub Makro1()
'
' Makro1 Makro
'

'
    Range("B39").Select
    Selection.Copy
    Range("G37").Select
    Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False
    SolverOk SetCell:="$C$20", MaxMinVal:=1, ValueOf:="0", ByChange:="$C$11:$AG$11"
    SolverSolve UserFinish:=True
    Range("J31").Select
    Selection.Copy
    Range("C39").Select
    Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False
End Sub

Something like that but with loop. New file beacuse i added new row.

I modifed your code

Sub Makro1()
i = Range("B" & Rows.Count).End(xlUp).Row

For Each cell In Range("B39:B" & i)

cell.Copy
Range("G37").PasteSpecial Paste:=xlPasteValues


SolverOk SetCell:="$C$20", MaxMinVal:=1, ValueOf:="0", ByChange:="$C$11:$AG$11"
SolverSolve UserFinish:=True

Range("J31").Copy
 cell.Offset(0, 1).PasteSpecial Paste:=xlPasteValues
 
Next

Application.CutCopyMode = False

End Sub

WORKS! BIG THANKS ALF. I am very very happy and appreciate your help and support big thanks again