The companies will be asked to merge by Sumner Redstone's National Amusements, the controlling shareholder of both companies, Reuters reported. Shares in both stocks rose on the report.
National Amusements, the controlling shareholder of Viacom (VIAB) and CBS (CBS), could reportedly call upon the companies to explore a merger this week.
The TV production group could reportedly be valued at up to $1 billion.
BTIG Analyst Rich Greenfield told CNBC Wednesday that a merger between Viacom and CBS is a logical next step after Viacom announced that CEO Tom Dooley will depart in November.