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 it's not clear if the investments are big enough to ensure that legendary investor Warren Buffett handled them.

Berkshire Hathaway’s (BRK/A, BRK/B) second-quarter 13F was filed after the market closed on August 14.

The "vote of confidence" from Buffett validates UnitedHealth's long-term value, but " (the) management needs to regain trust and credibility with investors, and get back to its beat-and-raise reputat...