The people also said that no committees have been formed.
CBS is widely seen as the stronger of the two companies.
Viacom Inc (VIAB) and CBS Corp (CBS) are not in active merger discussions, although controlling shareholder Shari Redstone has had exploratory conversations with CBS directors about recombining the companies, two sources familiar with the situation told Reuters on Friday.
"Shari is determined to get them back together", said one of the sources.
The move was being pushed by Shari Redstone, vice chair of Viacom and CBS, and president of the privately held National Amusements which controls both companies, according to The Wrap.
Redstone was not immediately available for comment.
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"Shares of both companies soared after the media website TheWrap reported Redstone is pursuing a combination of Viacom and CBS".
CBS has become the country's most-watched network under Moonves, who's credited with identifying and nurturing such hits as "The Big Bang Theory", "NCIS" and "Bull".
None of the parties involved are commenting on the record about potential merger talks, but shares of both CBS and Viacom have spiked based on the report.
But Viacom shut down talks later that year, after the younger Redstone pulled the plug on the proposal, supporting then-new Viacom chief Bob Bakish and telling Recode last year that there was better value in CBS and Viacom remaining separate.
"I was never a great proponent of the split of the two companies", she said at a media conference in November 2016. Shares in Viacom closed at $33.76, up 9.57% for the day. Analysts and investors predicted the blockbuster deal would trigger other consolidations, including a recombination of Viacom and CBS.
But that was before Walt Disney (DIS) agreed to acquire 21st Century Fox (FOXA) entertainment assets. But as recently as previous year, Shari Redstone said that a merger would have squashed Viacom's "momentum".