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.

UnitedHealth Group Inc. (NYSE:UNH) extended its rebound Monday, climbing another 3% in premarket trading after soaring 12% on Friday. The surge followed revelations that Warren Buffett’s Berkshire Hathaway Inc.

Warren Buffett’s Berkshire Hathaway revealed a position in embattled healthcare giant UnitedHealth Group while showing smaller stakes in longtime holdings Apple and Bank of America, according to a regulatory filing Thursday.

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.

Berkshire Hathaway’s portfolio added six new stocks, including the three new secret stocks. Warren Buffett was a net seller of stocks for the eleventh straight quarter.

Warren Buffett's Berkshire Hathaway has placed a major bet on a recovery at UnitedHealth Group, disclosing a new $1.6 billion stake in the insurance giant.

Warren Buffett has requested confidentiality in a new Berkshire Hathaway position. Will investors find out the stock Thursday?

See Berkshire Hathaway Inc.'s strategy with a big new stake in UnitedHealth. Learn how it's hedging against recession and stagflation. Click for my BRK.A update.