Chicago-based Mercy Health System formally joined Michigan-based Trinity Health last week.
Trinity, one of the nation's largest Catholic health care systems, will invest up to $150 million over the next five years as part of its acquisition of Mercy. The two signed a letter of intent to negotiate a union late last year.
Trinity last year acquired Loyola University Health System in suburban Chicago and agreed to invest $400 million in that system through 2018.
Trinity operates 48 hospitals in 10 states. It has $3.1 billion of outstanding debt and reported more than $7.4 billion in unrestricted revenue in fiscal 2011. All three rating agencies rate Trinity double-A with stable outlooks.
The merger would give Trinity an added foothold in the Chicago-area market. Mercy operates a 479-bed hospital on Chicago's south side and 11 clinics throughout the area. Mercy carries a below-investment-grade rating due to its long struggles, though it has seen recent improvement in operating performance.