Cliffs would purchase all of U.S. Steel for all cash and then sell off the Big River Steel subsidiary to Nucor, sources told CNBC's David Faber. U.S. Steel's headquarters would remain in Pittsburgh under the deal.

U.S. Steel shares rose after CNBC reported that Cleveland-Cliffs is partnering with Nucor for a possible bid to buy U.S. Steel.

Cliffs is partnering with peer Nucor to prepare a potential bid for U.S. Steel, a person familiar with the matter told Reuters on Monday. Cleveland-Cliffs would purchase U.S. Steel in an all-cash deal,