Wow, it does look like one, but the volume is ping-ponging, leaving open the possibility that it could move up once more.
Usually when a stock has had a long run like this one has, I look to the monthly chart for confirmation of a major re-trace. Usually the monthly chart has a double or triple negative divergence in the MACD or RSI-14. CNI still looks strong, so I'd be hesitant to call it the real deal.
stockcharts.com[h,a]waclyiay[pc9!c13!c20!d20,2!c50!c200!b50!b200!f][vc60][iLa12,26,9!Lh5,5!Li10,10!Lp14,3,3!Ll14!Lo14!Lb14!Le5,10,1!Lh89,34!Lh45,17!Li180,68!Lp3,2,2!Lb5]&pref=G |