Warren Buffett’s firm Berkshire Hathaway Inc. (NYSE:BRK.A) (NYSE:BRK.B) has purchased more shares of DaVita HealthCare Partners Inc (NYSE:DVA), according to regulatory filings with the Securities and Exchange Commission. The firm bought 1.13 million additional shares of the company this week, which makes Berkshire’s stake in DaVita nearly 18%.

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Berkshire holds more than 37 million shares

After the new share purchases, Berkshire Hathaway Inc. (NYSE:BRK.A) (NYSE:BRK.B) holds a 17.7% stake in DaVita HealthCare Partners Inc (NYSE:DVA), which amounts to 37.62 million shares. DaVita’s market value was $2.54 billion at Wednesday’s closing price. The filing indicates that Berkshire bought the shares between Monday and Wednesday at prices ranging from $66.12 to $68 a share.

Berkshire Hathaway Inc. (NYSE:BRK.A) (NYSE:BRK.B) has been snapping up shares of DaVita HealthCare Partners Inc (NYSE:DVA) for years, starting back in fall 2011. Then in May 2013, the firm said it wouldn’t buy more than a 25% stake in DaVita or to begin a proxy battle or push for seats on the company’s board of directors.

CNBC notes that despite Warren Buffett’s attachment to Berkshire Hathaway Inc. (NYSE:BRK.A) (NYSE:BRK.B), the firm’s growing stake in DaVita HealthCare Partners Inc (NYSE:DVA) hasn’t been his purchase. Instead, portfolio manager Ted Weschler has been buying those shares and was the one who signed the agreement with the company.

Charlie Munger donates Berkshire shares

Another SEC filing indicates that Charlie Munger, Buffett’s long-time business partner, has donated 100 shares of Berkshire Hathaway Inc. (NYSE:BRK.A) Class A stock to Harvard-Westlake, a co-ed prep school located in Los Angeles. Munger has long been giving money to the school, which is where Munger Science Center is located.

Munger said last year that he was purposely lower his net worth by making donations to schools because he won’t need all that money where he’s eventually going. So far his biggest gift was $110 million worth of Berkshire Hathaway Inc. (NYSE:BRK.A) (NYSE:BRK.B) shares, which he gave to University of Michigan in April of last year.