On Monday, Ameristar Casinos (NASDAQ:ASCA) announced the death of CEO Craig H. Neilsen. The company said that Neilsen -- who had built the company from the ground up and held a controlling stake in the company -- passed away unexpectedly in his sleep on Nov. 19 at his home in Las Vegas. He was 64.

Neilsen's controlling stake will be transferred to his private foundation, the Craig H. Neilsen Foundation, which is primarily focused on spinal cord injury research and treatment. The successor co-trustees of the foundation are Neilsen's son, Ray Neilsen, and Ameristar Executive Vice President and Co-Chairman of the Board Gordon R. Kanofsky.

Company President John M. Boushy -- who had just joined the company this past August while defecting from rival Harrah's Entertainment (NYSE:HET) -- has been elected by Ameristar's board of directors to succeed Craig Neilsen as CEO. Ray Neilsen and Kanofsky have been elected co-chairmen.

Interestingly, Ameristar's stock is up 20% this morning, to a new all-time high of $30.82. This likely has little to do with Neilsen's position as CEO; Neilsen was named "Best Performing CEO" by the American Gaming Association in 2002, and he was inducted into the American Gaming Association's Gaming Hall of Fame in 2005. This morning's spike is more likely related to the fact that Neilsen held a controlling interest in the company and was determined to grow Ameristar as a stand-alone company, despite Ameristar's value as a buyout candidate.

Neilsen's death would seem to open the door to potential acquirers such as Pinnacle Entertainment (NYSE:PNK), MGM Mirage (NYSE:MGM), or Las Vegas Sands (NYSE:LVS); however, Ameristar noted in this morning's press release that it was Neilsen's wish for the Craig H. Neilsen Foundation "to retain its controlling interest in Ameristar for the long term."

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Ameristar is a Motley Fool Hidden Gems recommendation.

Fool contributor Jeff Hwang owns shares of Ameristar Casinos. The Fool's disclosure policy can be found here.