A Swedish automaker has quit a deal to purchase Saab from General Motors (GM), casting doubt about the future of the troubled brand. Koenigsegg Group AB said Tuesday it has decided to back out of the deal, which was announced in June. GM did not provide financial details of the acquisition. The collapse of the Saab sale is the third GM deal to fail this year. GM chief executive Fritz Henderson said in Detroit that the automaker is disappointed by Koenigsegg"s decision and will take the next several days to figure out next steps.