LOUISVILLE, Ky.--(BUSINESS WIRE)--Humana Inc. (NYSE: HUM) announced today that it has completed its previously announced sale of the stock of its wholly-owned subsidiary, Concentra Inc. (Concentra), to MJ Acquisition Corporation for approximately $1.055 billion in cash, subject to customary adjustments. MJ Acquisition Corporation is a joint venture between Select Medical Holdings Corporation (NYSE: SEM), a leading operator of specialty hospitals and outpatient rehabilitation clinics in the U.S.