Thornburg Mortgage Inc., based in Santa Fe, New Mexico, lost 27 percent more than it had expected selling off adjustable-rate mortgages since August, after the collapse of the sub-prime market this summer.

Thornburg sold $22 billion of ``high quality'' adjustable- rate mortgages since Aug. 10, almost 8 percent more than it had planned, the company said in a statement today. Its estimated loss on the assets sales was $1.1 billion, versus a previous prediction of $863 million. There could be further changes to their estimates when quarterly earnings are reported on Oct. 16.

``The global dislocation of the mortgage finance and credit markets this past summer has had a greater impact on our balance sheet than we initially estimated,'' Larry Goldstone, Thornburg's president and chief operating officer, said in the statement. ``However, we have begun to see a modest improvement in financing conditions since August.''

The lender concentrates on so-called jumbo loans, which exceed the $417,000 limit for mortgages that government-chartered Fannie Mae and Freddie Mac can buy. Borrowers are having difficulty refinancing or selling their homes at favorable terms as lenders have tightened standards and U.S. home prices have dropped following a surge in defaults on loans to people with poor credit histories or heavy debts.

Thornburg, which is scheduled to report quarterly earnings on Oct. 16, said ``there could be further changes'' to its estimates for the adjustable-rate mortgage sales. The company said it's continuing to gather documentation for the transactions.