UNH stock soared after Warren Buffett’s Berkshire Hathaway revealed it bought shares of the healthcare company. Nonetheless, UnitedHealth faces a long list of unresolved issues.

Buffett owned UnitedHealth shares before selling his stake in 2010, though his Berkshire Hathaway recently acquired shares.

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.

What Happened: The undisclosed investments of Berkshire Hathaway have been made public. The company has reportedly invested in steelmaker Nucor NUE +1.07% Get Free Report , homebuilders D.R. Horton DHI +1.30% Get Free Report and Lennar LEN +1.56% Get Free Report , with the total investments amounting to $1.8 billion.

Warren Buffett’s Berkshire Hathaway (BRK.B) sold shares in Apple (AAPL) last quarter, [while adding UnitedHealth](https:

I told MarketWatch readers on Aug. 14 that Warren Buffett was about to reveal one big mystery elephant for Berkshire Hathaway’s portfolio — one $5 billion investment in the shares of an industrial giant.

The blue-chip Dow Jones ended higher after hitting an intraday record high on Friday, as UnitedHealth's shares jumped after Berkshire Hathaway raised its stake, but other Wall Street indexes slipped as mixed data clouded the Federal Reserve's next monetary policy move.

Warren Buffett's Berkshire Hathaway built a $1.6 billion stake in UnitedHealth last quarter, marking one of its last wagers with the investor as CEO.