The unsuccessful talks on an alliance involving Nissan Motor Co., its partner, Renault SA, and U.S. auto giant General Motors Corp. has left Carlos Ghosn, head of the Japanese-French carmaker, looking for a way to deal with slumping sales.

Initially, the three-month negotiations were seen mainly as an effort to revive ailing GM, the world's-largest automaker. The idea of a three-way tieup was suggested in late June by major GM shareholder Kirk Kerkorian, who has expressed frustration with the U.S. automaker's poor sales.

But the talks also cast a spotlight on Nissan-Renault's struggle to map out a convincing growth strategy.