CityMD and Summit Medical Group have signed a definitive agreement to merge, the urgent care chain and independent medical group announced Thursday.

New York City-based CityMD and Berkeley Heights, N.J.-based Summit will be supported by Warburg Pincus, the private-equity firm that acquired a majority stake in CityMD in June 2017.

"Our companies are united by a shared belief that upholding a patient-centered philosophy in today's environment means providing convenient, on-demand access to outstanding primary care, cutting-edge specialty care and a breadth of ancillary services," Dr. Jeffrey Le Benger, chairman and CEO of Summit Medical Group, said in prepared remarks.

Founded in 2010 by a group of emergency medicine physicians, CityMD has grown to more than 120 locations across New York, New Jersey and Washington.

Summit has more than 900 physicians at 80-plus locations including comprehensive ambulatory care campuses and a cancer center.

It recently expanded its footprint by acquiring Bend Memorial Clinic, which has 120 doctors in Oregon, to form Summit Medical Group Oregon as well as Arizona Primary Care Physicians and its 51 providers in the Phoenix area to form Summit Medical Group Arizona.