Berkshire now reports owning more than 14 million shares of DaVita's stock. The Omaha-based conglomerate reported its latest purchases of 42,400 shares to the Securities and Exchange Commission on Friday.
Berkshire now controls 14.7 percent of DaVita's stock.
Berkshire's investment in Denver-based DaVita has grown significantly since it first disclosed owning 2.7 million DaVita shares at the end of 2011.
DaVita runs nearly 2,000 outpatient dialysis clinics.
Berkshire officials generally don't comment on these filings. Many investors who follow Buffett believe the DaVita investment was likely the work of one of Berkshire's two other investment managers, not Buffett.
Berkshire Hathaway Inc.: www.berkshirehathaway.com