Biondi and Higgins started King Street, which manages $20 billion in total, in 1995. Still, the two, who according to Forbes are recent billionaires, have managed to avoid publicity, steering clear of the financial media.

Pine River’s Fixed Income Fund, co-led by Goldman Sachs and Citadel bond investment veteran Steve Kuhn, fell 2.5 percent in 2015, according to performance information seen by Reuters.

Kuhn was known for big profits on residential mortgage-backed securities following the financial crisis, but investments in corporate junk bonds triggered last year's losses, according to a person with knowledge of the performance.

A Pine River spokesman declined to comment.

Lions And Tigers

Funds that bet on other types of debt also suffered.

The main fund of Deepak Narula’s Metacapital, a mortgage investment specialist that in 2012 was the world's best-performing hedge fund manager in the over-$1 billion category, fell about 1.5 percent through November, according to performance information that Reuters saw.

Hedges on a U.S. Federal Reserve rate hike and long-term debt from government-backed mortgage financiers Fannie Mae and Freddie Mac were among the factors that snapped Narula's winning streak over the year’s first three quarters, according to an October letter to clients. A representative for $1.8 billion Metacapital did not respond to a request for comment.

Libremax and CQS sustained first-time losses in funds that focus on structured credit, or pools of loans for homes, office buildings or cars.

Greg Lippmann, a former Deutsche Bank mortgage trader played by actor Ryan Gosling in the Hollywood film "The Big Short," has averaged 10 percent annual returns in his main Libremax fund since it started in 2010. But that includes a drop of 0.4 percent in 2015 through November, according to performance information seen by Reuters.