On November 8th, the United States Court of Appeals for the Ninth Circuit (the "Ninth Circuit") addressed what plaintiffs must plead to invoke the fraud-on-the-market presumption in aid of class certification in a securities fraud case. Joining the United States Courts of Appeals for the Third and Seventh Circuits, and affirming a district court decision, the Ninth Circuit held that plaintiffs must show that the security in question was traded in an efficient market and that the alleged misrepresentations were public. Plaintiffs must also plausibly allege, but need not prove, that the claimed misrepresentations were material. Proof of materiality, or rebuttal of the fraud-on-the-market presumption, is a matter for trial or summary judgment, not a matter to be taken up in a class certification motion. Connecticut Retirement Plans and Trust Funds v. Amgen Inc.