Hedge fund manager Solus Alternative Asset Management, known for its investment in retail chain Toys “R” Us, told investors this week that it is shutting its flagship fund and will restrict redemptions as it works to sell off holdings, according to a letter viewed by The Wall Street Journal.

Solus is a frequent lender to distressed borrowers, with large holdings in energy companies, and its troubles come as market participants grapple with volatility and forced selling driven by a collapse in oil prices.