While the "vote of confidence" from Buffett's investment validates the long-term value of UnitedHealth shares, the "management needs to regain trust and credibility with investors, and get back to its beat and raise reputation of the past," said James Harlow, senior vice president at Novare Capital Management.

The flurry of 13-F filings to the Securities and Exchange Commission revealed that many of the most highly regarded investors were drawn into UnitedHealth in the second quarter.

The stake was valued at about $1.57 billion.

The Dow Jones Industrial Average and S&P 500 rose to new record highs Friday, as the Dow benefited from UnitedHealth Group’s stock pacing its largest single-day gain in nearly five years in the wake o...

The blue-chip Dow Jones ended higher after hitting an intraday record high on Friday, as UnitedHealth's shares jumped after Berkshire Hathaway raised its stake, but other Wall Street indexes slipped ...

However, recent labor market weakness and signs that tariff-induced inflation was yet to reflect in headline consumer prices have made investors confident of a potential dovish move next month.