Thirty hedge funds and banks are fighting a bid to force them to divulge details of their trading in the debt of Washington Mutual Inc., the former parent of Washington Mutual Bank.

The battle has erupted in the parent company's bankruptcy case, where bondholders have been giving JPMorgan Chase & Co. a rough time over its $1.9 billion purchase of the ailing Seattle thrift.

JPMorgan Chase said it is entitled to know details about who it is up against and how much they have riding on the outcome.

The list of bondholders includes affiliates of Goldman Sachs Group Inc., Deutsche Bank AG, Citigroup Inc. and Bank of America Corp. Aggregate holdings are all they want to report, according to a filing Wednesday in U.S. Bankruptcy Court in Wilmington, Del. Disclosing their trading histories means tipping their hands in the debt markets, and that is unfair, bondholders said in court papers.

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