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.

Warren Buffett’s Berkshire Hathaway revealed a new stake in troubled insurer UnitedHealth last quarter, according to a regulatory filing, a surprising buy because of the company’s current reputation, ...