Paramount is preparing to announce the departure of its chief executive, Bob Bakish, as soon as next week, according to three people with knowledge of the matter, a sudden development even as the company is exploring a merger.

The impending move is a result of Mr. Bakish’s worsening relationship with Shari Redstone, the company’s controlling shareholder, the people said, asking not to be identified discussing a delicate matter. Ms. Redstone grew frustrated with what she saw as his inability to get important deals across the finish line, including a sale of the Showtime and BET cable channels, the people said.