The Wall Street Journal
reported that Shari Redstone, widely seen as heir apparent atop the media conglomerate, and her father "had a major falling out." The report cited a person familiar with the situation.
The news pushed Viacom shares up as investors speculate the uncertainty about Viacom's management could cause the elder Redstone, Viacom's controlling shareholder, to sell the company.
Last year Redstone surprised Wall Street by firing Viacom chief Tom Freston and replacing him with two longtime sidekicks, Philippe Dauman and Tom Dooley.
Shares rose $1.28 to $42.50.