Buffett, through Berkshire, bought more than 5 million shares of the managed care company, worth an estimated $1.6 billion. Meanwhile, Michael Burry, who became famous in the book and movie The Big Short for his bet against subprime mortgages, bought 20,000 shares. Billionaire David Tepper also increased his stake in the name during the quarter.

So while we should always try to assess where a stock or sector is headed, the better way to trade is with a simple framework: Any stock can go up and thus be a source of profits. However, owning each stock comes with different levels of risk,

Berkshire Hathaway's $1.6 billion stake in UnitedHealth Group is helping to lift the Dow Jones Industrial Average to a new record as investors pile into healthcare sector funds.