Warehouse commitments at GMAC Bank, the depository arm of GMAC LLC, have declined 58% over the past year, to $2.5 billion.
A company official, requesting anonymity, confirmed the figures last week but said the unit has increased credit to "our existing core customer base" by $400 million this year.
GMAC Bank has scaled back its business and eliminated subprime credits, the official said.
"We are lending to customers that are selling loans to our conduit."
The official also said that GMAC Bank is keeping "a low profile" these days. Its parent is trying to become a bank holding company and is waiting for enough investors in its corporate notes to accept an exchange offer that would allow it to raise $30 billion of regulatory capital.
A few years ago GMAC was the nation's largest warehouse lender.