On June 6th, the Supreme Court unanimously ruled that private securities fraud plaintiffs do not need to prove loss causation in order to obtain class certification. Plaintiffs alleged that Halliburton made numerous misrepresentations to inflate its stock price, in violation of the Securities Exchange Act and Rule10b-5, and sought class action status. The District Court found that the suit could not proceed as a class action because Fifth Circuit precedent required securities fraud plaintiffs to prove "loss causation," that the defendant's deceptive conduct caused the investors' claimed economic loss, in order to obtain class certification. The District Court concluded that plaintiffs had failed to satisfy that requirement and the Fifth Circuit agreed. Reversing, the Supreme Court held that although securities fraud plaintiffs must prove certain things in order to invoke the fraud-on-the-market presumption of reliance, loss causation is not one of them. Loss causation addresses a matter different from whether an investor relied on a misrepresentation. Erica P. John Fund, Inc. v. Halliburton Co.