Billionaire Petr Kellner, the Czech Republic's richest man, died in a helicopter crash in Alaska over the weekend. Kellner, who was 56, was the majority stakeholder of the privately held PPF Group NV.

The crash near Knik Glacier on Saturday killed five people, including Kellner and the pilot, Alaska State Troopers said. The only other person onboard was in serious condition but is currently stable as of Sunday at a hospital in Anchorage. The group is believed to have been heli-skiing in the area, but the cause of the crash is still under investigation.

Kellner's net worth was valued at over $17 billion, according to the Forbes 2020 list of the world's richest people.

Beginning in 1991, Kellner has spent the past 30 years growing the Czech Republic's largest private-equity group, PPF Group NV, holding a majority stake of 98.93%. The international investment company is based in Amsterdam and operates in 25 countries across Europe, Asia and North America, with assets of 44 billion euros ($51.8 billion) as of mid-2020.

PPF Group stated that Kellner's "professional life was known for his incredible work ethic and creativity."

Kellner's death comes at a transitional time for the investment company, with PPF Group possibly looking to sell a minority stake in its telecommunications unit Cetin Group BV, either directly or through an initial public offering, according to Bloomberg sources. The deal could value the company at more than 6.7 billion euros ($8 billion), Bloomberg reported.

With Kellner's passing, PPF Group has appointed minority stakeholder and long-term business partner of Kellner, Ladislav Bartonicek, as the company's new lead. Bartonicek is one of only two other shareholders besides Kellner, holding a 0.535% in the business.

"The company states that its founder's passing away has no impact on the PPF Group's day-to-day functioning. PPF Group will continue moving forward its investment plans and visions formulated by Petr Kellner with his team of colleagues," PPF Group said in a statement on Monday.