NEW YORK — General Growth Properties Inc., which filed the biggest real-estate bankruptcy in U.S. history, asked a judge to approve an increased $400 million loan from new lenders to continue operations while under court protection.

In court documents filed today in U.S. Bankruptcy Court in New York, General Growth said it replaced its earlier lender, William Ackman's Pershing Square Capital Management LP, with new investors. It didn't give a reason for replacing Pershing, which had agreed to provide a $375 million bankruptcy loan.

The new proposed loan includes a commitment of as much as $210 million from San Francisco-based private-equity firm Farallon Capital Management LLC and as much as $110 million from New York-based Luxor Capital Group, according to the filing.

General Growth, whose Hawaii properties include Ala Moana Center and Ward Centers, filed for bankruptcy April 16 after amassing $27 billion in debt during an acquisition spree that turned it into the second-largest shopping mall owner behind Simon Property Group Inc.

The company's other new lenders include CanPartners Investments IV LLC, Perry Principals Investments LLC, Delaware Street Capital Master Fund LP, Pandora Select Partners LP and four funds run by Whitebox Advisors LLC, court papers show.