[table="width: 500"]
[tr]
[td]Private Sub Worksheet_Change(ByVal Target As Range)
Dim Cell As Range
If Not Intersect(Target, Columns("A:B")) Is Nothing Then
Application.EnableEvents = False
For Each Cell In Intersect(Target, Columns("A:B"))
Cells(Cell.Row, "C").Value = Cells(Cell.Row, "A").Value & Cells(Cell.Row, "B").Value
Cells(Cell.Row, "C").Characters(Len(Cells(Cell.Row, "A").Value) + 1).Font.Bold = True
Next
Application.EnableEvents = True
End If
End Sub[/td]
[/tr]
[/table]