DAVOS, SWITZERLAND—There is trouble brewing in China that may cause a global depression, the influential investor and philanthropist George Soros told attendees at a private dinner on the sidelines of the World Economic Forum. 

While China and Russia are notable absences from this year's gathering—Russia banished for its invasion of Ukraine and the Chinese held at home by severe anti-Covid policies—they were the primary target of Soros' speech, a fixture of the annual conference of global business and political leaders.