A trustee recovering assets for investors in the multibillion-dollar Bernard Madoff (MAY'-dawf) fraud has sued a New York-based investment management company that operated a hedge fund that invested heavily with Madoff.

The lawsuit was filed in December and unsealed on Monday in U.S. Bankruptcy Court in Manhattan. It says Tremont helped funnel more than $4 billion into Madoff's Ponzi scheme through its headquarters in Rye.

Trustee Irving Picard says Tremont managed the second largest group of feeder funds to assist Madoff in his fraud. Picard says Tremont should return more than $2.1 billion it received in transfers from Madoff in return for its 15-year investment.