The latest to leave the $22 billion firm were Derek Smith, a partner and senior investment adviser who has been with BlueMountain since 2008, and Dave Gibbs, a senior credit trader at the firm since October 2004. Both left in December.

"Like any company, BlueMountain undergoes changes in the make-up of its team that reflect the needs of investors and market dynamics," a spokesman said in an emailed statement on Wednesday. "The result is that the firm remains nimble, responsive and well-positioned to continue to thrive," he added.

Performance at the firm was lackluster in 2017.

BlueMountain's Credit Alternatives Fund gained 1 percent and its Global Volatility Fund gained 0.05 percent for the year, according to a report from HSBC's Alternative Investment Group seen by Reuters. The hedge fund benchmark HFRI Asset Weighted Composite Index gained 6.5 percent for the year.

The spokesman, Tom Vogel, declined to comment on the firm's returns.

Others to leave last year were credit portfolio manager Marina Lutova, who also left December to join Citadel LLC, and Peter Greatrex, a managing partner and head of private investments, who left in February.

The firm said in a regulatory filing in March 2017 that it employed roughly 238 people in New York and London.

BlueMountain said it hired 50 people in 2017, including Michael Mauboussin as director of research in May and Lance Rosen as head of equities in June.

In July, the firm named Lee Kempler as chief operating officer for investments, a newly created role, and hired Claudio Macchetto, who had been with hedge fund Paulson & Co, as head of platform distribution.

This month, Guillaume Cendrier joined as portfolio manager for Relative Value Credit.

BlueMountain, co-founded by Andrew Feldstein who is currently its chief investment officer, gained some fame for being one of the hedge funds on the other side of JP Morgan's bet on credit derivatives known as the "London Whale."

For a time the hedge fund employed Jes Staley, who had headed JP Morgan's investment bank and is now chief executive officer of Barclays.

(Additional reporting by Lawrence Delevingne; Editing by Tom Brown)

By Svea Herbst-Bayliss

Stocks treated in this article : Barclays, JP Morgan Chase & Company