Option Explicit
Sub abc()
Dim a, i, j, max
Cells.Interior.ColorIndex = xlNone
For j = 1 To ActiveSheet.UsedRange.Columns.Count
a = Cells(1, j).Resize(Cells(Rows.Count, j).End(xlUp).Row).Value
max = 0
For i = 1 To UBound(a)
If max < a(i, 1) Then max = a(i, 1)
Next
For i = 1 To UBound(a)
If a(i, 1) = max Then Cells(i, j).Interior.Color = vbYellow
Next
Next
End Sub