
CBS and Viacom are both controlled by ailing Sumner Redstone, 94, and his daughter Shari, through their privately owned movie theater company, National Amusements Inc.
Sumner Redstone split Viacom and CBS into separate companies a decade ago. He and his daughter attempted to merge the two in 2016, but the effort failed.
National Amusements, CBS and Viacom declined to comment.
Entertainment and media news website The Wrap on Friday reported that Shari Redstone was seeking to merge Viacom and CBS, sending Viacom shares up as much as 15%, to US$35.55.
Viacom shares fell, but were still trading up 7% in after hours trading following reports that a merger was not being pursued.