Ken Griffin, Founder and CEO of Citadel, speaks to the Economic Club of New York at The Plaza Hotel in New York City, U.S., November 21, 2024.Billionaire investor Ken Griffin's flagship hedge fund at Citadel climbed double digits in 2025, navigating a volatile year marked by sharp market swings, trade tensions and a late-year rebound in risk assets.Citadel's flagship multistrategy Wellington fund, its largest, gained 10.2% in 2025, according to a person familiar with the firm's returns who asked to remain a ...