The groups were ranked by the total number of employees at the listed practice versus just the number of practicing physicians.
- Southern California Permanente Medical Group — 12,022 physicians
- The Permanente Medical Group (Oakland, Calif.) — 10,712 physicians
- Select Physical Therapy (King of Prussia, Pa.) — 8,630 physicians
- Mayo Clinic Physicians (Rochester, Minn.) — 5,342 physicians
- HCA Florida Healthcare (Tampa, Fla.) — 7,180 physicians
- Ascension Medical Group (Indianapolis) — 4,671 physicians
- Northwell Health Physician Partners (New York City) — 4,724 physicians
- U.S. Anesthesia Partners (Maitland, Fla.) — 3,642 physicians
- Healthcare Partners IPA (Hicksville, N.Y.) — 5,042 physicians
- Geisinger Health Physicians (Mechanicsville, Pa.) — 3,621 physicians
