联合健康(UNH.N)跌幅扩大至16%，创下自2020年4月以来最低水平。美司法部正在调查联合健康医疗保险账单操作。

Core Viewpoint - UnitedHealth (UNH.N) has seen its stock price drop by 16%, reaching its lowest level since April 2020, amid an investigation by the U.S. Department of Justice into its medical billing practices [1] Company Summary - UnitedHealth's stock decline is significant, marking a 16% decrease [1] - The current stock price is the lowest it has been since April 2020 [1] - The U.S. Department of Justice is conducting an investigation into the company's medical billing operations [1]