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.

UnitedHealth Group Inc. shares jumped after funds piled into the company, which has been hampered by a federal probe into its business practices and weakening results.

“We think that most of their problems, if not all of them, are temporary in nature,” says Marshfield’s co-portfolio manager Elise Hoffmann.