Another big M&A announcement in the oil patch is making news after ConocoPhillips (COP) said it will buy Marathon Oil (MRO) for $17.1 billion in stock. The deal includes $5.4 billion in debt, bringing the enterprise value of the transaction to approximately $22.5 billion. The purchase price represents a roughly 15% premium to Marathon stock's May 28 close at $26.45, sending its share price up by more than 9% Wednesday. COP stock, meanwhile, is down about 3%.Under the agreement, Marathon shareholders will re ...