Lehman Brothers may have grounds to sue Goldman Sachs and Barclays after they demanded $1.2 billion in additional margin to assume trading positions auctioned by a Chicago exchange, bankruptcy examiner Anton Valukas said.

Goldman was the high bidder for Lehman’s equity derivatives at options and futures exchange CME Group, and took $445 million of those assets at a private auction in September 2008, according to previously censored details of Valukas’s report.

Barclays was the high bidder for Lehman’s energy derivatives and took $707 million in assets from CME.

DRW Trading was the highest bidder for Lehman’s foreign exchange, agricultural and interest-rate derivatives, Valukas said.

“The examiner concludes that an argument can be made that the transfers at issue were fraudulent transfers,” Valukas said in the report.