Tenet Healthcare's medical center in Atlanta

Tenet Healthcare and United Surgical Partners International (USPI) will combine their ambulatory and short-stay surgery centers in a deal that will give Tenet the option to buy USPI over the next five years.

Tenet will pay $425 million to private equity firm Welsh, Carson, Anderson & Stowe and other USPI shareholders and assume $1.5 billion of USPI's debt for a 50.1 percent stake in the venture.