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.

Warren Buffett’s Berkshire Hathaway revealed a position in embattled healthcare giant UnitedHealth Group while showing smaller stakes in longtime holdings Apple and Bank of America, according to a regulatory filing Thursday.

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

The biggest immediate changes will be that different people will be in control of the company's stock portfolio, and Abel will have power over Berkshire's $344 billion cash hoard. However, portfolio managers Ted Weschler and Todd Combs have been managing more of Berkshire's investments as the years have progressed.

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.

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.

Leveraged positions in the stock market jumped 18% in one month and topped $1 trillion for the first time. Increasing use of debt to invest can tell us a lot about investors' attitudes. And while this has always been the case,