The Supreme Court made decisions on four class action cases, clarifying certification standards and expressing dislike for class action arbitration. The Court favored both corporate defendants and plaintiffs in different cases, but made it harder to get class certification. The Court saved the "fraud on the market" presumption for another day, pleasing plaintiffs. Classwide relief through arbitration now seems unlikely. The Court criticized the Fifth, Eighth, and Ninth Circuits. In the Wal-Mart case, the Court agreed the class didn't meet commonality requirements and was improperly certified for damages.