Shares of UnitedHealth Group surged nearly 14% on Friday after billionaire Warren Buffett's Berkshire Hathaway bought 5 million shares of the company, providing a shot in the arm for investors who think the health conglomerate will turn around under its new CEO.

Berkshire Hathaway's $1.6 billion stake in UnitedHealth Group is helping to lift the Dow Jones Industrial Average to a new record as investors pile into healthcare sector funds.

If any investor has stood the test of time, it is Warren Buffett, and with good reason. For years, the “Oracle of Omaha” has had a rock-star-like presence in the investing world, and his annual Berkshire Hathaway shareholders meeting draws thousands of loyal fans who are investors.

Shares of UnitedHealth Group are surging before the market open Friday as Warren Buffett’s Berkshire Hathaway disclosed that it recently purchased shares of the beleaguered insurer.

The investment comes as UnitedHealth faces soaring medical costs, federal investigations, the fallout of the killing of a top executive and a cyberattack last year.

By Mariam Sunny and Shashwat Chauhan (Reuters) -Shares of UnitedHealth Group surged more than 9% on Friday after a fresh investment from billionaire Warren Buffett's Berkshire Hathaway boosted investor confidence in the troubled health conglomerate.

Buffett owned UnitedHealth shares before selling his stake in 2010, though his Berkshire Hathaway recently acquired shares.

UnitedHealth Group, the worst-performing stock in the Dow Jones Industrial Average so far this year, got a major boost last week from billionaire investor Warren Buffett. That doesn’t mean everyone else should buy.