In recent years the Supreme Court has accrued a record overwhelmingly favoring defendants in securities class actions, so a few double takes were in order when, on April 27, the justices unanimously ruled in favor of the plaintiffs in Merck & Co., Inc. v. Reynolds.

“I was fall-off-the-chair stunned,” says Adam Savett, director of Securities Class Action Services at RiskMetrics Group, an investment risk adviser. “It certainly is the first ‘plaintiff-friendly’ decision in a securities class action from the Supreme Court in quite some time.”