Key Takeaways Buffett has long been a big proponent of the index funds that Bogle helped bring to the masses.However, his public declaration that Bogle is an American hero may have also been influenced by the fact that one of Bogle's funds just helped Buffett win a $1 million bet.

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.

According to Thursday's filing, as of June 30, Berkshire held around 7.2 million shares of Lennar, 6.6 million of Nucor and 1.5 million shares of D.R. Horton, thanks to purchases made over the past t...