Pardus Capital Management, an activist hedge fund with over $2 billion in assets, said it suspended investor withdrawals in the face of slumping values of some of its investments.
Pardus, which holds positions in both Delta Air Lines and United Air Linesand has urged the companies to merge, said it suspended redemptions "to protect the funds and their investors from external short-term pressure."
Hedge funds often suspend investor withdrawals when demands for a return of investor money would force them to off-load securities at bargain-basement prices.
Shares of Delta and UAL Corp. , United Air's parent, have fallen recently.
"We have taken a long-term investment perspective," Pardus said in a statement.
"The funds have been disproportionately affected by recent market volatility."