Yet as UnitedHealth's stock declined, Buffett's Berkshire Hathaway Inc. (BRK.B) (BRK.A) stepped in and bought 5.04 million shares, a stake valued at $1.57 billion as of June 30's close.

But should you buy the three highest-yielding dividend stocks in the S&P 500 now? To start to answer that question, investors should weigh their track records and financials. second-quarter earnings ...