DaVita HealthCare PartnersEnough about energy. DaVita HealthCare Partners ( DVA) is another name that should sound familiar to Buffett disciples. And the Oracle of Omaha is buying more in 2013. Berkshire Hathaway added 1.5 million shares to its portfolio in the latest quarter, boosting its total stake to $1.79 billion. >>5 Toxic Stocks to Sell Before It's Too Late DaVita operates more than 1,850 dialysis clinics and in-patient hospital dialysis units across the U.S., serving patients who suffer from chronic kidney failure. The long-term nature of dialysis treatment makes DVA's business pretty predictable, since kidney transplants are scare. DaVita has been cautious about its relationship with Buffett's firm -- the two parties agreed to a deal in May that limits Berkshire Hathaway's ownership of DVA to 25%. The latest trade brings the DVA stake to 14.8%. A $4.4 billion merger with HealthCare Partners changed DVA's business dramatically in the past year, putting medical practices, hospitals, and pharmacy services under DVA's umbrella for a 25% contribution to corporate revenues. But none of that changes the fact that DVA trades for a premium right now. While demographic tailwinds should keep a steady stream of patients at DVA's doors, much of that upside is already priced into shares.