the ticker and trading information for blackstone group is displayed at the post where it is traded on the floor of the new york stock exchange nyse april 4 2016 reutersbrendan mcdermid oct 20 reuters  investment firm blackstone inc bxn said on wednesday it would buy a majority stake in spanx valuing the underwear maker at 12 billion spanx founder and chief executive officer sara blakely would become the executive chairwoman of spanxs newly appointed board reporting by deborah sophia in bengaluru editing by shailesh kuber