The 68-year-old professional wrestling promoter reportedly lost an estimated $350 million when World Wrestling Entertainment's shares dropped 49 percent in premarket trading on Friday.
The stock's tumble came a day after the company announced it had landed a new television deal with Comcast Corp.'s NBCUniversal Cable Entertainment.
The WWE is attempting to get 1 million subscribers for its network before the end of the year as the company strives to make up for lost business in pay-per-view and video on demand.
McMahon, who owns 52 percent of the WWE's stock, became a billionaire for the first time in 2000.
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