Somme ligne variable

Sub ajout_formule_stock()
Dim der_col As Long, i As Long, deb As Long
der_col = Range("XV1").End(xlToLeft).Column

For i = 2 To Range("A66536").End(xlUp).Row
    If Range("B" & i) = "stock" Then
    deb = i - 1
        Do While deb > 1 And Range("B" & deb) <> "stock"
        deb = deb - 1
        Loop
    deb = deb + 1
    Range("D" & i).FormulaR1C1 = "=RC[-1]+SUM(R" & deb & "C:R[-1]C)"
    Range("D" & i).AutoFill Destination:=Range(Cells(i, 4), Cells(i, der_col)), Type:=xlFillDefault
    End If
Next i
End Sub