The fraud-on-the-market theory, first accepted by the U.S. Supreme Court in Basic Inc. v. Levinson, 485 U. S. 224 (1988), and recently endorsed in Erica P. John Fund, Inc. v. Halliburton Co., 563 U. S. ___ (2011), presumes that the price of a security traded in an efficient market will reflect all publicly available information about a company.  With that presumption, a buyer of the security may be presumed to have relied on that information in purchasing the security, including misrepresentations in public communications.  In Amgen, Inc. v. Connecticut Retirement Plans and Trust Funds (Feb. 27, 2013), the U.S. Supreme Court took up the question of whether, at the certification stage, materiality must be proven.  Affirming the Ninth Circuit, the majority concluded that materiality need not be proven at the certification stage.

Summarizing the holding of the Court, Justice Ginsburg wrote:

While Connecticut Retirement certainly must prove materiality to prevail on the merits, we hold that such proof is not a prerequisite to class certification. Rule 23(b)(3) requires a showing that questions common to the class predominate, not that those questions will be an­swered, on the merits, in favor of the class. Because mate­riality is judged according to an objective standard, the materiality of Amgen’s alleged misrepresentations and omissions is a question common to all members of the class Connecticut Retirement would represent. The al­leged misrepresentations and omissions, whether material or immaterial, would be so equally for all investors com­posing the class. As vital, the plaintiff class’s inability to prove materiality would not result in individual questions predominating. Instead, a failure of proof on the issue of materiality would end the case, given that materiality is an essential element of the class members’ securities fraud claims. As to materiality, therefore, the class is entirely cohesive: It will prevail or fail in unison. In no event will the individual circumstances of particular class members bear on the inquiry.

Essentially, Amgen, also the dissenters from today’s decision, would have us put the cart before the horse. To gain certification under Rule 23(b)(3), Amgen and the dissenters urge, Connecticut Retirement must first establish that it will win the fray. But the office of a Rule 23(b)(3) certification ruling is not to adjudicate the case; rather, it is to select the “metho[d]” best suited to adjudi­cation of the controversy “fairly and efficiently.”

Slip op., at 2-3.  With the heavy tide of anti-class decisions emanating from the U.S. Supreme Court of late, this is an important reminder that certification analysis focuses on common questions, not proof.