Tenet Healthcare Corp. has announced it has signed a definitive agreement with United Surgical Partners International (USPI) to combine their short-stay surgery and imaging center assets into a new joint venture.

Tenet will initially own 50.1% of the joint venture, which will be the largest provider of ambulatory surgery in the United States. Private equity investor Welsh Carson and the other existing investors in USPI will initially own the remaining 49.9%.

Tenet will have the ability to acquire USPI over the next five years.

The joint venture, which will maintain the USPI brand, will have ownership interests in 244 ambulatory surgery centers, 16 short-stay surgical hospitals and 20 imaging centers in 29 states.

In a separate transaction, Tenet entered into an agreement to acquire Aspen Healthcare from Welsh Carson. Aspen operates nine private hospitals and clinics in the U.K. USPI owned Aspen until a restructuring of the USPI group in 2012, which resulted in Aspen becoming an independent company majority owned by Welsh Carson.