I used to work for Xtra when the buyout was supposed to happen. Long story short Xtra never received all of the money so the certificate never transferred owners. Both are still separate. Which leads me to the question of who's certificate did they finally buy since I thought PEX gave up on trying to get their own.
PEX paid Xtra a money just to say they bought them so they could raise more money from investers to complete the buyout. Which never happened.