UnitedHealth will acquire DaVita’s physician group for about $4.9 billion in cash. DaVita Medical Group operates nearly 300 clinics across a half-dozen states — including the Everett Clinic, which provides care to patients in Snohomish and King counties. In another example of the blurring boundaries in the health-care industry, UnitedHealth Group, one of the nation’s largest insurers, said it is buying a large physician group to add to its existing roster of 30,000 doctors.UnitedHealth’s Optum unit will acquire the physician group from DaVita Inc. for about $4.9 billion in cash, subject to regulatory approval. DaVita Medical Group operates nearly 300 clinics across a half-dozen states — including the Everett Clinic, whose nearly 400 physicians provide health care to more than 320,000 patients in Snohomish and King counties, according to its website. DaVita’s main business is operating a chain of for-profit dialysis centers. With the purchase of the physician group, UnitedHealth is incr...