"While Dan focuses his energy on the rehabilitation process, our teams across the family of companies will continue to execute at a high level, serving and supporting our clients and team members," Farner said.

Quicken Loans, a privately held company and Detroit's largest employer, has not disclosed details of Gilbert's health condition. He is believed to have been rehabilitating at the Shirley Ryan AbilityLab, which is ranked No. 1 in the country for stroke rehab by U.S. News and World Report.

Earlier this month, Gilbert appeared in a video distributed to employees of his Quicken Loans, Bedrock LLC and other affiliated companies

The video showed a thinner, bearded Gilbert sitting upright and saying he was at a rehab center in "downtown Chicago, Illinois."

"Thank you for all of your well wishes and all of the letters, notes, emails, voice mails, texts, whatever it is, I read every single one of them and I really appreciate it," Gilbert said in the video message to employees. "It keeps me going."