Sumner Redstone files for divorce

Has been married to Paula Fortunato Redstone since 2003

Sumner Redstone has filed for divorce -- a week after he sold a boatload of CBS and Viacom stock.

The 85-year-old billionaire said in court documents he wishes to divorce Paula Fortunato Redstone, 46, due to "irreconcilable differences." The two have been married since April 2003.

This month, the media mogul sold $233 million of stock in CBS and Viacom, the two companies he controls as majority shareholder and executive chairman, apparently in order to meet a margin call on his core holding National Amusements. Those sales came as the shares were near 52-week lows.

Redstone was worth as much as $9 billion before the recent swoon on Wall Street cut shares of Viacom in half and did even more damage to CBS.

He has also seen the value of his 12 million or so shares of Midway Gaming plunge 68% in the last four weeks.

Insiders say a prenuptial agreement calls for Redstone to pay his spouse $5 million and that he'll likely be more generous than the law requires.

"After five and a half years together, we have amicably ended our marriage," Redstone said Tuesday in a written statement. "While this is a difficult decision for both of us, we remain close and supportive friends and are committed to each other's continued happiness and success. We will have no further comment and hope that you will respect our privacy."

Redstone has had some famously rocky relationships, including with his first wife, his children, colleagues like Tom Freston and actor Tom Cruise.