UnitedHealth Group (UNH) stock is still down 40% YTD but has surged more than +20% this month following reports that Warren Buffett, and other billionaire hedge fund managers have taken a stake in the company.

This investment signifies Buffett's re-entry into UNH after liquidating his entire position back in 2010, indicating that he perceives significant value at

Shares of UnitedHealth Group Inc. (NYSE: UNH) climbed 2.81% in Monday's pre-market trading session, extending Friday's gain following Michael Burry and Warren Buffett's stake acquisition in the insurance behemoth.

Warren Buffett's Berkshire Hathaway built a $1.6 billion stake in UnitedHealth last quarter, marking one of its last wagers with the investor as CEO.

Buffett & Co. picked up UnitedHealth stock on the cheap, with the embattled blue chip one of the newest holdings in the Berkshire Hathaway equity portfolio.

Bloomberg journalists discuss today's biggest winners and losers in the stock market. Listen for analysis on the companies making news on Wall Street.

On Friday, high-profile investors Michael Burry and Warren Buffett took positions in UnitedHealth Group Inc. (NYSE:UNH). Warren Buffett's fund bought little more than 5 million shares, and Burry disclosed in 13F filings that he purchased call contracts against 350,

Futures for the Dow Jones Industrial Average and other major stock indexes traded sharply mixed Friday as Wall Street reacted to the U.S. retail sales report. Meanwhile, UnitedHealth GroupUNH soared on the stock market today after famed investor Warren Buffett disclosed a new position.