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 some of UnitedHealth’s peers got a bump in the wake of Berkshire’s investment in the healthcare giant, and they all look cheaper based on price relative to expected earnings.

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.

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

The blue-chip Dow opened at a record high on Friday, as UnitedHealth's shares jumped after Berkshire Hathaway raised its stake in the health insurer, while expectations of an interest rate cut in September also lifted the mood.

The blue-chip Dow was on track to open at a record high on Friday, underpinned by expectations of an interest rate cut in September and gains in UnitedHealth's shares after Berkshire Hathaway raised its stake in the health insurer.