Several high-profile departures this year have reminded observers of Citadel's reputation as a challenging place to work.
Derek Kaufman, Citadel's head of global fixed income, resigned in April after nearly seven years at the firm following a $1 billion loss on various trades over 2014. Another to leave recently—despite strong performance last year—was Brandon Haley, head of global equities and a nine-year veteran (two former co-heads of equities also left in recent years, Jeff Runnfeldt in 2012 and Steve Weller in 2013).
And Oliver Weisberg, a managing director based in Hong Kong, left earlier this year to join a family office for Alibaba executive vice chairman Joseph Tsai. Three investment employees in Hong Kong also recently left as part of the reduction in Citadel's macro strategy.
To be sure, those departures are a fraction of Citadel's 500 investment staffers and 1,400 employees overall. But Citadel has a reputation for employee churn.
"Citadel has a strong record of attracting alpha producers, but turnover is very high compared to other hedge funds," said Kate Quinn, an investment industry recruiter at DHR International who has worked with Citadel in the past.
"Top performers come to Citadel because the work is demanding and they embrace the challenge," Citadel's Spring said in response to what she called "misperceptions" about the firm's workplace and turnover.
Firmwide turnover is around 10 percent annually, according to a person familiar with the situation (the figure for investment staffers specifically was unclear).
Hedge fund firms comparable to Citadel often have lower turnover—"much less" than 10 percent—according to Jacob Navon and Adam Herz of executive recruiting firm Westwood Partners.
The pair said that turnover rates depend on many factors, including firm culture, style of investing, performance and assets managed. Navon and Herz cautioned that between zero percent and 5 percent turnover can be considered natural attrition and each firm has different policies on automatic employee replacement, making direct comparisons difficult.
Citadel client Yusko acknowledged that Citadel has a reputation for turnover but said it didn't concern him. "There's a very low tolerance for B players. I think their turnover is a good sign," he said.
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Citadel receives about 20,000 resumes each year, according to a person with knowledge of the firm's hiring, and offers positions to about 2 percent of the pool. The person also said the average tenure of Citadel employees is about five years; it's nine years for senior executives.
Citadel ranked 10th for Great Workplaces in Financial Services for 2015 by Great Places to Work, the company whose employee satisfaction surveys are used to create the Fortune 100 Best Companies to Work.