Credit: Jerod Harris/Getty Images

Sumner Redstone, the ailing, 92-year-old media magnate, has resigned as executive chairman of CBS and is being replaced by Leslie Moonves, the company’s chief executive officer.

Moonves will continue to serve as president and CEO and Redstone has been appointed chairman emeritus, CBS announced Wednesday. He was nominated by Redstone’s daughter Shari, and was appointed by a unanimous vote of the CBS directors.

Before Moonves’ appointment, Redstone’s daughter was offered the position of non-executive chair, but she declined in light of her other professional responsibilities. She will continue to serve as vice chair of the CBS board, a position she’s held since 2005.

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“I want to thank Sumner for his guidance and strong support over all these years,” Moonves said in a statement. “It has meant the world to me.”

Moonves joined CBS in 1995. He has held positions as president of CBS Entertainment (1995-1998), president and CEO of CBS Television (1998-2003) and chairman of CBS Television (2003-2004). In 2004, he became co-president and co-COO of Viacom and remained so until CBS’s separation from Viacom in 2006 when he became president and CEO of CBS Corp.

“I have been fortunate to work with Les and he has clearly established himself as a creative and effective leader who understands both the challenges and the opportunities that are shaping today’s media landscape,” said Shari Redstone in a statement. “I am sure he will make a great Chair and I look forward to working with him for many years to come.”

A recent lawsuit filed by a former girlfriend had raised questions about Redstone’s mental competence and fitness as executive chairman of both CBS and Viacom. He currently retains the latter position.