Berkshire Hathaway buys more shares of DaVita

Berkshire Hathaway CEO Warren Buffett
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OMAHA, Neb. Billionaire Warren Buffett's company continues buying stock in kidney dialysis firm DaVita (DVA) and now controls nearly 16 percent of the company.

Berkshire Hathaway (BRK.A) filed an update on its latest DaVita purchases Wednesday with the Securities and Exchange Commission.

Berkshire now owns more than 14.8 million shares of DaVita's stock. In recent months, Berkshire has been steadily buying stock in the Denver-based company that runs nearly 2,000 outpatient dialysis clinics.

Berkshire's stake in the company has grown significantly since it first disclosed owning 2.7 million DaVita shares at the end of 2011.

Berkshire officials don't generally comment on these filings. Several investors who follow Buffett believe the DaVita investment was likely the work of one of Berkshire's two other investment managers, not Buffett.