Two major hospital operators are in talks about a possible merger that would create the largest U.S. hospital owner, as a series of major deals are poised to consolidate control of the health-care landscape into fewer hands.

Ascension and Providence St. Joseph Health, both nonprofits, are talking about combining, according to people familiar with the discussions.

A deal would create a new operation of unprecedented reach, with 191 hospitals in 27 states and annual revenue of $44.8 billion, based on the most recent fiscal year. That would dethrone the nation's largest pure hospital operator, HCA Healthcare.

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