Ascension, the largest Catholic not-for-profit health system in the country, will become even larger after agreeing to acquire Presence Health, the largest Catholic hospital system in Illinois.

The numbers: Ascension — with 141 hospitals and more than $22 billion in annual revenue — has had decent profit margins while Presence Health has been losing a lot of money on its 12 hospitals and $2.7 billion in annual revenue. Financial terms of the deal were not disclosed, but based on Presence Health's financial statements and recent going rates for hospital transactions, the deal could be worth at least $1 billion — and possibly a lot more.

Why it matters: Hospital and health system consolidation is a continuing trend and almost always results in higher prices for patients.