DaVita (NYSE: DVA), one of the largest U.S. providers of kidney dialysis services, delivered fourth-quarter profit more than double last year's. The standout quarter benefitted from greater sales and higher patient visits at the company's treatment centers. Dialysis treatments administered in the U.S. climbed 12%, with DaVita providing 5.2 million treatments in the quarter.  

DaVita earned $1.58 a share, up from $0.70 for the same quarter a year earlier -- analysts had expected just $1.49 for the period. The company's not making headlines only for its upbeat earnings, however; Warren Buffett's Berkshire Hathaway (NYSE: BRK-B) disclosed that it added the healthcare stock to its roster of legendary picks, along with opening a position in Liberty Media (Nasdaq: LMCA). This is big news for investors familiar with Buffett, since stocks that join the ranks of Berkshire typically lead a life of outperformance. 

However, the Wall Street Journal suggests the new investments in DaVita and Liberty may not have been Buffett's picks. The "Oracle of Omaha" likes to go big or go home, and given the small stakes in these companies, it's likely that new Berkshire investment manager Ted Weschler picked them up. Berkshire added 2.68 million shares of the dialysis services provider for a total value of $203 million, while the company's 1.7 million shares of Liberty Media finished the year with a net value of $132 million.

Whether a member of the Berkshire team or Buffett himself chose the fund's latest investments, I would keep an eye on these picks by adding them to your Motley Fool Watchlist -- it's free.

• Add Liberty Media to My Watchlist.

• Add DaVita to My Watchlist.

• Add Berkshire Hathaway to My Watchlist.