Warren Buffett and his team have built up an equity portfolio worth nearly $295 billion at today's prices. It's chock-full of value stocks, but Buffett's focus when buying stocks is investing in great companies. In other words, it's only a real value if the stock is underpinned by a top industry player.

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 has attracted major contrarian investors like Buffett, Burry, and Simons. Click here to read why UNH stock is a Buy.

This investment signifies Buffett's re-entry into UNH after liquidating his entire position back in 2010, indicating that he perceives significant value at