Deutsche Bank AG, Germany's biggest bank, reported a surprise third-quarter profit after new accounting rules allowed it to book fewer asset writedowns.

The bank rose as much as 9.1 percent in Frankfurt trading after posting net income of 435 million euros. Analysts had predicted a loss. Rules easing requirements for marking down investments reduced writedowns for the quarter by 845 million euros to 1.2 billion euros.

Chief Executive Officer Josef Ackermann, who has so far resisted pressure to raise capital or take government help, said financial markets remain "challenging" and indicated the bank may trim its dividend. Banks from UBS AG in Zurich to New York-based Citigroup Inc had to accept state aid after the bankruptcy of Lehman Brothers Holdings Inc froze credit markets.