The proposed merger between CBS and Viacom has been withdrawn by Shari Redstone, vice chair of the board for both companies, sources told CNBC's David Faber.

Redstone, who had pushed for the companies to explore a merger, is reversing course and now backs acting CEO Bob Bakish and his plan to bring the Viacom back to prominence. Redstone now wants Viacom to remain an independent company, according to sources on both sides of the proposed deal.