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

According to Berkshire's most recent filing, which is as of June 30, it has bought approximately 5 million shares of UnitedHealth Group. It's a notable position for Berkshire, but it's not a huge one -- UnitedHealth accounts for just 0.5% of its total portfolio.