One Medical has quietly struck a series of partnerships with large health systems, including UCSF Health in San Francisco, UC San Diego Health, Dignity Health and Providence St. Joseph Health. (Photo: One Medical)

A private equity-backed medical group that's been forging ties with hospital systems around the U.S. to better coordinate patient care and control costs has signed a new deal in one of the nation's most crowded health-care markets.

One Medical, which raised $350 million last year from investment giant Carlyle Group LP, is joining Mount Sinai's network of independent physicians in New York. The deal will make it easier for patients to move among One Medical's nine primary-care clinics and Mount Sinai's specialists and hospitals, executives from both entities said.

One Medical has quietly struck a series of similar arrangements in recent years with other large health systems, including UCSF Health in San Francisco, UC San Diego Health, Dignity Health and Providence St. Joseph Health.