Nov. 10 (Bloomberg) -- GMAC LLC, the financing arm of General Motors Corp. gripped by a cash squeeze, faced new collateral calls from Fannie Mae that prompted GMAC to sell the servicing on $12.7 billion of home loans in the third quarter, according to a regulatory filing.

GMAC also provided Fannie Mae with $200 million in additional collateral after the tangible net worth of its Residential Capital home-loan unit fell below $1 billion, the Detroit-based company said in a filing today.

The $12.7 billion in servicing rights that it sold represents 9 percent of the loans ResCap handles for Fannie Mae, the filing said. Servicing refers to the billing and back-office work involved in mortgage lending.

In accepting the added collateral, Fannie Mae said it wouldn't take additional action involving ResCap until Jan. 31, GMAC said. Those actions include reducing ResCap's ability to sell and service loans or requiring the lender to transfer the loans to Fannie Mae, according to the filing.

GMAC last week said its third-quarter net loss widened to a record $2.52 billion from $1.6 billion a year earlier. GMAC, led by Chief Executive Officer Alvaro de Molina, 51, was hurt by slumps in the housing market, where foreclosures are running at record levels, and in auto sales, which GM labeled the worst since 1945 when it reported October results last week.

ResCap, which ranked among the biggest U.S. subprime lenders two year ago, has posted losses totaling $9.1 billion over the past eight quarters.

GMAC has been shut out of some credit markets, and the firm on Nov. 6 repeated its hopes of converting to a bank holding company, which could make it eligible for help from the Treasury's $700 billion bailout fund. It's unclear whether regulators will approve GMAC's application, Chief Financial Officer Robert Hull said last week.

To contact the reporter on this story: David Mildenberg in Charlotte at dmildenberg@bloomberg.net

Last Updated: November 10, 2008 12:00 EST