Had a number of strange little subsidiaries (Enterprise, Chalice, Hip, Safice).
The distribution deal with Atlantic was a poisoned one, and a small clause of it gave away rights on the masters to Atlantic, which enforced it once taken over by Warner Bros in 1968.
This part of the catalog (from start to 68) still belongs to Atlantic nowadays, while the other part of the catalog and the Stax brand is now in Concord's hands (thanks to the merger with Fantasy who acquired Stax remains after the bankrupt of 76).
The Atlantic part of the catalog has been also reissued by Rhino and/or sublicensed to Collectables.
Please note that Concord also owns the rights on the pre-68 material that was not actually released at that time...