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.

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 latest regulatory filing revealed that the company took a considerable stake in UnitedHealth. The 5 million-share, $1.6 billion stake makes the massive health insurer the 18th-biggest position in Berkshire's portfolio. Buffett's company also trimmed its positions in Apple and Bank of America.