How do you plan to have the user enter the search criteria?
a textbox  with a "Search" or "Filter List" button?
or a change event with the text  box?

Either way,
I believe what you have to do is use the ListBox.RemoveAll method, then
use a loop:
For inx = 0 To AddEntry.cmbFund1.ListCount - 1
If (InStr(1, ComboBox.List(inx), StringBeingSearched) > 0) Then
Listbox.additem combobox.list(inx)
msg = msg & Chr(13) & combobox.list(inx)
End If
Next inx
MsgBox msg

The listbox will then have only entries that contain the string being searched.

Of course, I didn't test this with your data, but I've done simliar.