You could use the if function to simply return blanks where B0.
=if( [condition] ,[result if true] , [result if false] )

In column C:
=if(colB<0,colA,"")

In column D:
=if(colB<0,colB,"")

This would give you a list but with blank spaces where column b0.

"Natalie" wrote:

I have 2 columns of data: date(A) & % return(B). I want 2 new columns (C&D)
to to return both data from columns A & B "if and only if B is <0". How
should I set my function? Thank you