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.

UnitedHealth Group shares popped Friday after Berkshire Hathaway announced it purchased 5 million shares of the insurance giant.

The lesson: Don't count out Berkshire Hathaway. Buffett's retirement announcement. The decision, at the very end of Berkshire's annual meeting, probably surprised a lot of fans who forgot he was 94.

Beaten-down UNH is set to challenge its 50-day moving average after a major vote of confidence from the Oracle of Omaha.

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 placed a major bet on a recovery at UnitedHealth Group, disclosing a new $1.6 billion stake in the insurance giant.

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.

Berkshire Hathaway just disclosed that it dumped $1.6 billion into a sinking ship, and Wall Street instantly paid attention.

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.