ConocoPhillips (NYSE:COP) announced it will buy Marathon Oil Corp (NYSE:MRO) for $22.5 billion, with the deal expected to close in the fourth quarter. Below, let's dig into how both stocks are reacting to the big merger. COP was last seen down 3% at $115.33, but former resistance at the $114 level could flip into support. Despite being in pullback mode since an April 12, more than one-year high of $135.18, shares still boast a 14.6% year-over-year lead.Meanwhile, MRO is up 8.4% at $28.68 at last check -- it ...