The fixed-income-focused fund lost 20% from March 1 through March 20, sources told Business Insider. The fund manages roughly $1.7 billion. For the year, the Obsidian fund is down more than 19% after returning more than 13% in 2019. Credit markets have been rocked by evaporating liquidity, ratings downgrades, and the Federal Reserve's decision to cut interest rates to zero. The Fed has since enlisted BlackRock to set up three different bond-buying programs. Visit Business Insider's homepage for more stories. BlackRock's oldest hedge fund, its 24-year-old Obsidian fund, was hit hard in March, sources say, falling 20% as of March 20.