NEW YORK (S&P Global Ratings) Dec. 6, 2017--S&P Global Ratings said today that its ratings on UnitedHealth Group Inc. (UNH; A+/Negative/A-1) and its subsidiaries are unaffected by UNH's announced $4.9 billion acquisition of DaVita Medical Group (DMG), a subsidiary of DaVita Inc. In our view, DMG, with its 300 medical clinics, 35 urgent care centers, and six outpatient surgery centers, is a good strategic fit with UNH subsidiary Optum Inc.'s health care delivery business (OptumCare). Although DMG has underperformed in recent years, we believe its competitive position and earnings will likely benefit from Optum's provider-focused services and data analytics. Financially, the $4.9 billion acquisition is larger than UNH's Surgical Care Affiliates acquisition in January 2017. However, we still view DMG