UnitedHealth Group was sued Wednesday for allegedly concealing how backlash from the killing of a top executive was damaging its business, causing its stock to nosedive after the insurer lowered its 2025 outlook.In a proposed class action filed in Manhattan federal court, shareholders said the insurer defrauded them after the Dec. 4 shooting of UnitedHealthcare Chief Executive Brian Thompson by shifting away from strategies that led to higher-than-average claims denials, without revealing the impact on prof ...