Dist. Ct. erred in certifying for class action treatment plaintiff-stockholder’s section 10(b) and Rule 10(b)5 actions, alleging that defendant made false statements about new growth strategy that involved softening of its underwriting standards that posed risk of increased auto claims, and then: (1) misrepresented that claims' frequency trends had been favorable, when at same time claims had actually been spiking; and (2) misled market by falsely attributing claims increases to other factors rather than instant growth strategy. Plaintiff also claimed that defendant’s eventual announcement that its growth strategy was cause of spike in claims caused sharp stock price drop. Under Halliburton II, 573 U.S. 258, Dist. Ct. improperly declined to consider defendant’s proffered evidence on price impact at class certification stage of proceedings. Ct. of Appeals, though, observed that section 10(b) and Rule 10(b)5 claims typically involve common issues that make them suitable for class action treatment, but that holding in Halliburton II required consideration of defendant’s claim that announcements had no impact on market, as well as any rebuttal by plaintiff.