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.

Berkshire Hathaway revealed four new investments Thursday in steelmaker Nucor, insurer UnitedHealth and two of the nation’s biggest homebuilders — Lennar and DR Horton — but only one of the investments was big enough to ensure that legendary investor Warren Buffett may have handled them.

Berkshire Hathaway has built up sizable investments in a handful of companies, according to a filing released on Thursday.