Oct. 27 (Bloomberg) -- Deutsche Postbank AG, Germany's biggest consumer bank by clients, reported a third-quarter loss related to the collapse of Lehman Brothers Holdings Inc. and writedowns from the financial crisis.

It had a pretax loss of 449 million euros ($560 million), after a profit of 350 million euros in the year-earlier period, the Bonn-based lender said in a statement today. Postbank slumped the most in four years in Frankfurt trading.

The lender may also raise about 1 billion euros in the fourth quarter by selling new shares to ``strengthen its capital base,'' Postbank said. It will sell shares for 18.25 euros each.

Lehman's Sept. 15 bankruptcy filing worsened the global credit crunch and prompted bailout packages by Germany and the U.S. to shore up bank capital. Postbank booked losses of 364 million euros from exposure to New York-based Lehman and wrote down 201 million euros on derivatives.

Postbank fell as much as 17 percent to 15.52 euros in Frankfurt and traded at 15.80 euros at 9:17 a.m., valuing the company at 2.61 billion euros.

Deutsche Bank AG, Germany's biggest bank by assets, agreed in September to buy almost 30 percent of Postbank for 2.79 billion euros and has an option to raise the stake.

Postbank also reported markdowns of 112 million euros on stocks, investment funds and structured credit products.

To contact the reporter on this story: Aaron Kirchfeld in Frankfurt at akirchfeld@bloomberg.net

Last Updated: October 27, 2008 04:22 EDT