DaVita, a company that provides dialysis services, saw shares tumbling Friday after issuing a weak outlook amid rising care costs, while big investor Berkshire Hathaway offloaded some shares in a preplanned agreement.

The health-care stock fell more than 12% Friday. The Colorado-based company said it expects its 2025 adjusted profit per share to be between $10.20 and $11.30, compared to analysts’ average expectation of $11.24 per share, according to LSEG.

The disappointing guidance underlined increasing patient care costs due to center closure costs and health benefit expenses. In the fourth quarter, the company incurred charges for closures of its dialysis centers in the U.S. totaling $24.2 million.

Still, DaVita’s fourth-quarter earnings of $2.24 per share on an adjusted basis topped analysts’ estimates of $2.13 per share per LSEG.

Separately, DaVita’s largest institutional investor Berkshire Hathaway sold 203,091 shares on Tuesday to reduce its stake to 45%, worth nearly $6.4 billion, a regulatory filing Thursday night showed.

The sale was part of a share repurchase agreement the two parties reached back in April. DaVita agreed  to buy back shares to reduce Berkshire’s ownership stake to 45% on a quarterly basis.

Warren Buffett’s conglomerate first invested in DaVita in 2011. As of the end of September, DaVita was Berkshire’s 10th largest equity holding.