Assured Guaranty Corp., fighting to avoid losses in the bankruptcy case of Stockton, Calif., asked a judge to reverse a ruling that it and other creditors failed to negotiate in good faith with the city, Bloomberg News reported yesterday. The insurer asked Bankruptcy Judge Christopher M. Klein to reverse his April 1 finding that so-called capital markets creditors acted as a "stone wall" during pre-bankruptcy negotiations with the city. Assured and other creditors had argued that the city should be thrown out of bankruptcy because it failed to negotiate with them in good faith. The judge rejected their arguments and found that the creditors were the ones who failed to negotiate seriously because they "voted with their feet" by quitting the talks, a ruling the company denied in court papers.