Viacom said it has elected CEO Philippe Dauman as executive chairman of the company, succeeding Sumner Redstone, who becomes chairman emeritus.
Redstone on Wednesday stepped down as chairman of CBS, succeeded by CEO Les Moonves.
The moves are a step toward succession at the media companies controlled by Redstone, who at 92 is in poor health and being questioned about his ability to make healthcare and financial decisions.
Viacom's board offered the chair's post to Redstone's daughter Shari Redstone, but she turned it down and will continue as non-executive vice chair.
On Wednesday, Shari Redstone said she supported the election of Moonves as chairman of CBS, but wanted a more independent chairman at Viacom.
Viacom has been performing poorly as its cable networks have suffered from the defection of young viewers from traditional TV to digital entertainment options. Its stock has also suffered, falling more than 40% last year.
Read more at broadcastingcable.com.