I'm surprised that it does work because I didn't know that there was a Word constant for wdBoldSingle - you should be using a boolean there.
You can simplify the code to
Code:
Sub FormatMacro()
Dim oRng As Word.Range
Set oRng = ActiveDocument.Range
With oRng.Find
.ClearFormatting
.Replacement.ClearFormatting
.Text = "<Life Insurance>"
.Replacement.Text = ""
.MatchWildcards = True
.Format = True
.Replacement.Font.Underline = wdUnderlineSingle
.Execute Replace:=wdReplaceAll
.Replacement.ClearFormatting
.Text = "<2.4.9>"
.Replacement.Font.Bold = True
.Execute Replace:=wdReplaceAll
End With
End Sub