DaVita shares plunged more than 9 percent Thursday, threatening to erase all of the dialysis provider’s gains the day before.
Warren Buffett‘s Berkshire Hathaway owns a 23 percent stake in DaVita.
The ballot measure would have capped the amount of money dialysis providers in the state can earn on treating certain patients.
Pushed by the Service Employees International Union, the measure would have limited the revenue dialysis providers could earn through rates from privately insured patients to 115 percent of the costs to provide the care.
DaVita, which operates half of all the chronic dialysis clinics in the state, had shelled out $ 66.6 million of the more than $ 110 million spent by the industry lobbying against Proposition 8.