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Amgen Punctuates Circuit Split: What Must Plaintiff Prove to Establish the Fraud-On-The-Market Presumption at Class Certification?

November 30, 2011

By WILLIAM F. SULLIVAN, PETER Y. CHO & TIMOTHY D. REYNOLDS

This Stay Current analyzes a recent Ninth Circuit decision that impacts securities class action litigants at the class certification stage. The decision involves the "fraud-on-the-market" presumption of reliance at class certification, and pertains to what plaintiffs seeking class certification must prove at that stage. The case also discusses -- and limits -- the scope of what defendants may rebut at the class certification stage. The Ninth Circuit opinion highlights a current split among the courts of appeals.