The deal with Vanguard is the biggest transaction Tenet has made and signals a shift from the company's problems over the past 10 years. Several Tenet-owned facilities underwent investigations in the early 2000s for alleged unnecessary heart surgeries. In 2006, Tenet paid $900 million in cash and returned Medicare payments to settle claims it overbilled Medicare throughout the 1990s in one of the largest settlements ever recorded in the hospital sector. Tenet also went through a messy lawsuit with CHS a few years ago after CHS unsuccessfully attempted to take Tenet over.