Domenic, a true work of art! Thank you.

Not to mar your elegant work with a beginner's learning, but: Assuming the
primary exchange is in Cell B1, all exchanges are in Cell G1, I modified the
formula to return the Primary Exchange if it Doesn't find a U.S. Exchange in
Cell G1:

=IF(ISERROR(MID(G1,LOOKUP(BigNum,FIND(List,G1)),FI ND(",",G1&",",LOOKUP(BigNum,FIND(List,G1)))-LOOKUP(BigNum,FIND(List,G1)))),B1,(MID(G1,LOOKUP(B igNum,FIND(List,G1)),FIND(",",G1&",",LOOKUP(BigNum ,FIND(List,G1)))-LOOKUP(BigNum,FIND(List,G1)))))

Please tell me, what is the logic of assigning BigNum with all of this? I
don't understand the logic of the formula.

Thanks, very slick.