Hmmm...
I then want to list the corresponding row in column a.
I interpret that to mean you want the formula entered in some cell in column
A that returns the *row number* of the cell in column B that meets the
condition.
From reading the other replies I'm the only one that interprets it in this
way.
If you do want to return the corresponding value from column A where column
B is <0 then try this array formula** :
=INDEX(A2:A20,MATCH(TRUE,B2:B20<0,0))
** array formulas need to be entered using the key combination of
CTRL,SHIFT,ENTER (not just ENTER). Hold down both the CTRL key and the SHIFT
key then hit ENTER.