Warren Buffett's Berkshire Hathaway has acquired 5 million shares in UnitedHealth Group , a regulatory filing showed on Thursday, sending the health insurer's stock up 7% in extended trading.

Some Washington policymakers with financial stakes in UnitedHealth Group are selling their stocks in the company as it struggles financially and the Trump administration investigates its billing practices.

UnitedHealth Group Inc. and Elevance Health Inc. told Colorado regulators they will exit some individual health plans in the state, the latest sign of instability in the Affordable Care Act marketplaces.

Health-insurance giant said it was making a number of governance changes, including the appointment of a new lead independent director and the formation of a public responsibility committee.

Andrew Witty's pay, UnitedHealth's challenges, and regulatory woes unfold. Learn what the $1.57B Berkshire stake means for this healthcare giant.

UnitedHealth Group (UNH) has recently been on Zacks.com's list of the most searched stocks. Therefore, you might want to consider some of the key factors that could influence the stock's performance in the near future.

CNBC's Bertha Coombs joins 'Squawk on the Street' with the latest details on UnitedHealth Group's turnaround efforts after a tumultuous year for the company.