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.

Here are some of the stocks making notable moves in Friday's premarket action: UnitedHealth shares are jumping more than 10% after Warren Buffett's Berkshire Hathaway said in a filing it had [built a

Warren Buffett's Berkshire Hathaway bought more than 5 million shares in UnitedHealth last quarter for a stake worth about $1.6 billion. Berkshire also added stakes in D.R. Horton, Lennar and Nucor, while trimming its Apple and Bank of America positions.