CEO Kent Thiry did say, however, that a final agreement with the U.S. investigators hasn't been reached yet, asserting, "We've been under the impression for more than a decade that the way we do things is fine, so we've had to do a lot of sorting out with them." Foolish final thoughts Of course, it's a safe bet that few companies would complain about Berkshire Hathaway standing as their single largest shareholder -- and for DaVita, that's a vote of confidence that cannot be overstated. As a result, and as long as they maintain Berkshire's seal of approval, I won't be closing my "outperform" CAPScall on the company anytime soon. More expert advice from The Motley Fool Thanks to the savvy of investing legend Warren Buffett, Berkshire Hathaway's book value per share has grown a mind-blowing 586,817% over the past 48 years. But with Buffett aging and Berkshire rapidly evolving, is this insurance conglomerate still a buy today ?