About 20 portfolio managers have left Steven A. Cohen’s hedge fund firm this year, including several who worked with Cohen for more than a decade, according to people familiar with the matter.

It is an unusual level of turnover for Cohen’s firm and marks the latest developments in the rocky relaunch of his fund. The 63-year-old billionaire investor launched Point72 Asset Management last year after an insider-trading scandal barred him from managing outside money until 2018.