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December 23, 2015
Brattle Economists Author Law360 Article Examining Methodology Findings in Halliburton Class Decision

Brattle Principals Torben Voetmann and Paul Hinton and Senior Associate Matthew Aharonian recently co-authored an article published on Law360, “Battle of the Experts: The Focus on Event Studies in Class Certification.”

The article examines four methodological findings in Judge Lynn’s Class Decision in Halliburton from an economist’s perspective, and describes their potential influence in future cases. The methodologies include a model estimation period; the speed of price adjustment; comparing price response to a peer index; and testing price impact across multiple corrective disclosures.

The authors discuss how this Class Decision provides a benchmark for how courts may compare the methodological choices of experts in securities class certification price impact analysis. Because the Class Decision qualified its assessments of the expert evidence as being relevant to this particular case, the qualifications may mean it will not have a strong precedent influence on future class certifications. However, the authors believe the decision may encourage courts to be more active in adjudicating event study methodology differences between experts in the future.

The full article can be downloaded below.