ConocoPhillips to Buy Marathon Oil in $17 Billion All-stock DealConocoPhillips has agreed to buy Marathon Oil ( NYSE:MRO ) in an all-stock transaction worth $17 billion, bolstering its shale assets as the broader oil and gas industry undergoes a wave of consolidation. The deal will add 2 billion barrels of resources to ConocoPhillips' inventory in the U.S., exte