U.S. refiner Marathon Petroleum proposed to buy Andeavor for more than $20 billion, the Wall Street Journal reported on Sunday.

The potential cash-and-stock deal, which values Andeavor at about $150 per share, is expected to be announced on Monday, the WSJ reported, citing sources.



The offer would represent a premium of 22.6 percent to Andeavor stock's Friday close.

The deal is expected to produce $1 billion of synergies, the paper said.

Marathon Chief Executive Gary Heminger is expected to run the combined company, with a senior role for Andeavor's chief executive, Gregory Goff, it said.

San Antonio, Texas-based Andeavor, formerly known as Tesoro, operates 10 refineries in the western United States with a refining capacity of about 1.2 million barrels per day, and ownership in a logistics business, according to Andeavor website.

Marathon and Andeavor were not immediately available for comment outside regular business hours.

For more on the reported deal, see The Wall Street Journal article.