** Media company's shares up 5.4 pct at $47 after CNBC reports that CEO Philippe Dauman is likely to become chairman, replacing Sumner Redstone
** Redstone, who is in poor health, resigned from his executive role at top of CBS Corp on Wednesday
** Redstone's daughter, Shari Redstone, did not want Dauman to succeed her father and insisted that both companies needed an "independent voice"
** Redstone controls about 80 pct of voting shares in Viacom and CBS through holding company
** CBS shares up 3.3 pct at $49.85
** Up to Wednesday's close, Viacom shares had risen 7 pct since Jan. 19, when activist investor Eric Jackson sought management shakeup at company